refactor: add ErrorProne and NullAway checks, fix some issues

.gitignore

@@ -39,5 +39,7 @@ jadx-output/
 *.orig
 quark.json
 
+.env
+
 cliff.toml
 jadx-gui/src/main/resources/logback.xml

build.gradle.kts

@@ -11,7 +11,9 @@ plugins {
 	id("com.diffplug.spotless") version "8.4.0"
 }
 
-val jadxVersion by extra { System.getenv("JADX_VERSION") ?: "dev" }
+val jadxEnv = loadEnv(file("$rootDir/.env"))
+
+val jadxVersion by extra { jadxEnv["JADX_VERSION"] ?: "dev" }
 println("jadx version: $jadxVersion")
 version = jadxVersion
 
@@ -19,7 +21,7 @@ val jadxBuildJavaVersion by extra { getBuildJavaVersion() }
 
 fun getBuildJavaVersion(): Int? {
 	val envVarName = "JADX_BUILD_JAVA_VERSION"
-	val buildJavaVer = System.getenv(envVarName)?.toInt() ?: return null
+	val buildJavaVer = jadxEnv[envVarName]?.toInt() ?: return null
 	if (buildJavaVer < 11) {
 		throw GradleException("'$envVarName' can't be set to lower than 11")
 	}
@@ -27,6 +29,24 @@ fun getBuildJavaVersion(): Int? {
 	return buildJavaVer
 }
 
+// control ErrorProne checks level, can be: off, warn, error
+val jadxBuildChecksMode: String by extra { getBuildChecksMode() }
+
+fun getBuildChecksMode(): String {
+	val buildChecksMode = jadxEnv["JADX_BUILD_CHECKS_MODE"]?.lowercase() ?: "off"
+	val expectedValues = listOf("off", "warn", "error")
+	if (!expectedValues.contains(buildChecksMode)) {
+		throw GradleException("Unknown check mode: '$buildChecksMode', should be one of $expectedValues")
+	}
+	if (buildChecksMode != "off") {
+		val javaVersion = jadxBuildJavaVersion?.let { JavaVersion.toVersion(it) } ?: JavaVersion.current()
+		if (!javaVersion.isCompatibleWith(JavaVersion.VERSION_21)) {
+			throw GradleException("Error Prone requires Java 21")
+		}
+	}
+	return buildChecksMode
+}
+
 allprojects {
 	apply(plugin = "java")
 	apply(plugin = "checkstyle")
@@ -82,6 +102,30 @@ fun isNonStable(version: String): Boolean {
 	return isStable.not()
 }
 
+fun loadEnv(file: File): Map<String, String> {
+	val envMap = HashMap<String, String>()
+	System
+		.getenv()
+		.filter { it.key.startsWith("JADX_") }
+		.forEach { envMap[it.key] = it.value }
+	if (file.exists()) {
+		file
+			.readLines()
+			.map { it.trim() }
+			.filter { it.isNotEmpty() && !it.startsWith("#") }
+			.forEach {
+				val (k, v) = it.split("=", limit = 2)
+				envMap[k.trim()] = v.trim()
+			}
+	}
+	println(
+		"Loaded env vars (${envMap.size}):\n${
+			envMap.toList().sortedBy { it.first }.joinToString(separator = "\n") { "${it.first}=${it.second}" }
+		}\n",
+	)
+	return envMap
+}
+
 val distWinConfiguration: Configuration by configurations.creating {
 	isCanBeConsumed = false
 }

buildSrc/build.gradle.kts

@@ -6,6 +6,8 @@ dependencies {
 	implementation("org.jetbrains.kotlin:kotlin-gradle-plugin:2.3.10")
 
 	implementation("org.openrewrite:plugin:6.19.1")
+	implementation("net.ltgt.errorprone:net.ltgt.errorprone.gradle.plugin:4.2.0")
+	implementation("net.ltgt.nullaway:net.ltgt.nullaway.gradle.plugin:2.3.0")
 }
 
 repositories {

buildSrc/src/main/kotlin/jadx-java.gradle.kts

@@ -1,14 +1,20 @@
 import org.gradle.api.tasks.testing.logging.TestExceptionFormat
+import net.ltgt.gradle.errorprone.CheckSeverity
+import net.ltgt.gradle.errorprone.errorprone
+import net.ltgt.gradle.nullaway.nullaway
 
 plugins {
 	java
 	checkstyle
 
 	id("jadx-rewrite")
+	id("net.ltgt.errorprone")
+	id("net.ltgt.nullaway")
 }
 
 val jadxVersion: String by rootProject.extra
 val jadxBuildJavaVersion: Int? by rootProject.extra
+val jadxBuildChecksMode: String by rootProject.extra
 
 group = "io.github.skylot"
 version = jadxVersion
@@ -24,6 +30,9 @@ dependencies {
 	testRuntimeOnly("org.junit.platform:junit-platform-launcher")
 
 	testCompileOnly("org.jetbrains:annotations:26.1.0")
+
+	errorprone("com.google.errorprone:error_prone_core:2.48.0")
+	errorprone("com.uber.nullaway:nullaway:0.13.1")
 }
 
 repositories {
@@ -62,3 +71,27 @@ tasks {
 		}
 	}
 }
+
+tasks.withType<JavaCompile>().configureEach {
+	val checkEnabled = jadxBuildChecksMode != "off"
+	if (checkEnabled) {
+		options.compilerArgs.add("-XDaddTypeAnnotationsToSymbol=true")
+	}
+	options.errorprone {
+		isEnabled = checkEnabled
+		allErrorsAsWarnings = jadxBuildChecksMode == "warn"
+		excludedPaths = ".*/test/.*"
+		nullaway {
+			if (jadxBuildChecksMode == "error") {
+				error()
+			}
+			annotatedPackages.add("jadx")
+		}
+		// TODO: fix and enable all checks
+		disable("MixedMutabilityReturnType")
+		disable("EqualsGetClass")
+		disable("OperatorPrecedence")
+		disable("UnusedVariable")
+		disable("ImmutableEnumChecker")
+	}
+}

jadx-commons/jadx-app-commons/src/main/java/jadx/commons/app/JadxCommonEnv.java

@@ -1,8 +1,10 @@
 package jadx.commons.app;
 
+import org.jetbrains.annotations.Nullable;
+
 public class JadxCommonEnv {
 
-	public static String get(String varName, String defValue) {
+	public static @Nullable String get(String varName, @Nullable String defValue) {
 		String strValue = System.getenv(varName);
 		return isNullOrEmpty(strValue) ? defValue : strValue;
 	}
@@ -23,7 +25,7 @@ public class JadxCommonEnv {
 		return Integer.parseInt(strValue);
 	}
 
-	private static boolean isNullOrEmpty(String value) {
+	private static boolean isNullOrEmpty(@Nullable String value) {
 		return value == null || value.isEmpty();
 	}
 }

jadx-commons/jadx-app-commons/src/main/java/jadx/commons/app/JadxCommonFiles.java

@@ -3,7 +3,8 @@ package jadx.commons.app;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.function.Function;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Supplier;
 
 import org.jetbrains.annotations.Nullable;
 import org.slf4j.Logger;
@@ -30,40 +31,39 @@ public class JadxCommonFiles {
 
 	static {
 		DirsLoader loader = new DirsLoader();
-		loader.init();
 		CONFIG_DIR = loader.getConfigDir();
 		CACHE_DIR = loader.getCacheDir();
 	}
 
 	private static final class DirsLoader {
-		private @Nullable ProjectDirectories dirs;
+		private final Path configDir;
-		private Path configDir;
+		private final Path cacheDir;
-		private Path cacheDir;
 
-		public void init() {
+		DirsLoader() {
 			try {
-				configDir = loadEnvDir("JADX_CONFIG_DIR", pd -> pd.configDir);
+				AtomicReference<@Nullable ProjectDirectories> pdRef = new AtomicReference<>();
-				cacheDir = loadEnvDir("JADX_CACHE_DIR", pd -> pd.cacheDir);
+				configDir = loadEnvDir("JADX_CONFIG_DIR", () -> loadDirs(pdRef).configDir);
+				cacheDir = loadEnvDir("JADX_CACHE_DIR", () -> loadDirs(pdRef).cacheDir);
 			} catch (Exception e) {
 				throw new RuntimeException("Failed to init common directories", e);
 			}
 		}
 
-		private Path loadEnvDir(String envVar, Function<ProjectDirectories, String> dirFunc) throws IOException {
+		private static Path loadEnvDir(String envVar, Supplier<String> dirFunc) throws IOException {
 			String envDir = JadxCommonEnv.get(envVar, null);
 			String dirStr;
 			if (envDir != null) {
 				dirStr = envDir;
 			} else {
-				dirStr = dirFunc.apply(loadDirs());
+				dirStr = dirFunc.get();
 			}
 			Path path = Path.of(dirStr).toAbsolutePath();
 			Files.createDirectories(path);
 			return path;
 		}
 
-		private synchronized ProjectDirectories loadDirs() {
+		private static ProjectDirectories loadDirs(AtomicReference<@Nullable ProjectDirectories> pdRef) {
-			ProjectDirectories currentDirs = dirs;
+			ProjectDirectories currentDirs = pdRef.get();
 			if (currentDirs != null) {
 				return currentDirs;
 			}
@@ -76,7 +76,7 @@ public class JadxCommonFiles {
 				LOG.debug("Loaded system dirs ({}ms): config: {}, cache: {}",
 						System.currentTimeMillis() - start, loadedDirs.configDir, loadedDirs.cacheDir);
 			}
-			dirs = loadedDirs;
+			pdRef.set(loadedDirs);
 			return loadedDirs;
 		}
 
@@ -95,11 +95,11 @@ public class JadxCommonFiles {
 			return impl;
 		}
 
-		public Path getCacheDir() {
+		Path getCacheDir() {
 			return cacheDir;
 		}
 
-		public Path getConfigDir() {
+		Path getConfigDir() {
 			return configDir;
 		}
 	}

jadx-commons/jadx-zip/src/main/java/jadx/zip/ZipReader.java

@@ -1,6 +1,7 @@
 package jadx.zip;
 
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Set;
@@ -9,6 +10,7 @@ import java.util.function.Function;
 
 import org.jetbrains.annotations.Nullable;
 
+import jadx.zip.fallback.FallbackException;
 import jadx.zip.fallback.FallbackZipParser;
 import jadx.zip.parser.JadxZipParser;
 import jadx.zip.security.IJadxZipSecurity;
@@ -39,13 +41,15 @@ public class ZipReader {
 
 	@SuppressWarnings("resource")
 	public ZipContent open(File zipFile) throws IOException {
+		if (!zipFile.exists()) {
+			throw new FileNotFoundException(zipFile.getAbsolutePath());
+		}
 		try {
 			JadxZipParser jadxParser = new JadxZipParser(zipFile, options);
 			IZipParser detectedParser = detectParser(zipFile, jadxParser);
-			if (detectedParser != jadxParser) {
-				jadxParser.close();
-			}
 			return detectedParser.open();
+		} catch (FallbackException e) {
+			throw e;
 		} catch (Exception e) {
 			if (options.getFlags().contains(ZipReaderFlags.DONT_USE_FALLBACK)) {
 				throw new IOException("Failed to open zip: " + zipFile, e);
@@ -90,7 +94,7 @@ public class ZipReader {
 		return options;
 	}
 
-	private IZipParser detectParser(File zipFile, JadxZipParser jadxParser) {
+	private IZipParser detectParser(File zipFile, JadxZipParser jadxParser) throws IOException {
 		if (zipFile.getName().endsWith(".apk")
 				|| options.getFlags().contains(ZipReaderFlags.DONT_USE_FALLBACK)) {
 			return jadxParser;
@@ -105,7 +109,7 @@ public class ZipReader {
 		return jadxParser;
 	}
 
-	private FallbackZipParser buildFallbackParser(File zipFile) {
+	private FallbackZipParser buildFallbackParser(File zipFile) throws IOException {
 		return new FallbackZipParser(zipFile, options);
 	}
 }

jadx-commons/jadx-zip/src/main/java/jadx/zip/fallback/FallbackException.java

@@ -0,0 +1,9 @@
+package jadx.zip.fallback;
+
+import java.io.IOException;
+
+public class FallbackException extends IOException {
+	public FallbackException(String message, Throwable cause) {
+		super(message, cause);
+	}
+}

jadx-commons/jadx-zip/src/main/java/jadx/zip/fallback/FallbackZipParser.java

@@ -22,39 +22,45 @@ import jadx.zip.security.IJadxZipSecurity;
 
 public class FallbackZipParser implements IZipParser {
 	private static final Logger LOG = LoggerFactory.getLogger(FallbackZipParser.class);
+
 	private final File file;
+	private final ZipFile zipFile;
 	private final IJadxZipSecurity zipSecurity;
 	private final boolean useLimitedDataStream;
 
-	private ZipFile zipFile;
+	public FallbackZipParser(File file, ZipReaderOptions options) throws FallbackException {
-
+		try {
-	public FallbackZipParser(File file, ZipReaderOptions options) {
+			this.file = file;
-		this.file = file;
+			this.zipFile = new ZipFile(file);
-		this.zipSecurity = options.getZipSecurity();
+			this.zipSecurity = options.getZipSecurity();
-		this.useLimitedDataStream = zipSecurity.useLimitedDataStream();
+			this.useLimitedDataStream = zipSecurity.useLimitedDataStream();
+		} catch (Exception e) {
+			throw new FallbackException("Error opening zip file: " + file.getAbsolutePath(), e);
+		}
 	}
 
 	@Override
 	public ZipContent open() throws IOException {
-		zipFile = new ZipFile(file);
+		try {
-
+			int maxEntriesCount = zipSecurity.getMaxEntriesCount();
-		int maxEntriesCount = zipSecurity.getMaxEntriesCount();
+			if (maxEntriesCount == -1) {
-		if (maxEntriesCount == -1) {
+				maxEntriesCount = Integer.MAX_VALUE;
-			maxEntriesCount = Integer.MAX_VALUE;
+			}
-		}
+			List<IZipEntry> list = new ArrayList<>();
-
+			Enumeration<? extends ZipEntry> entries = zipFile.entries();
-		List<IZipEntry> list = new ArrayList<>();
+			while (entries.hasMoreElements()) {
-		Enumeration<? extends ZipEntry> entries = zipFile.entries();
+				FallbackZipEntry zipEntry = new FallbackZipEntry(this, entries.nextElement());
-		while (entries.hasMoreElements()) {
+				if (isValidEntry(zipEntry)) {
-			FallbackZipEntry zipEntry = new FallbackZipEntry(this, entries.nextElement());
+					list.add(zipEntry);
-			if (isValidEntry(zipEntry)) {
+					if (list.size() > maxEntriesCount) {
-				list.add(zipEntry);
+						throw new IllegalStateException("Max entries count limit exceeded: " + list.size());
-				if (list.size() > maxEntriesCount) {
+					}
-					throw new IllegalStateException("Max entries count limit exceeded: " + list.size());
 				}
 			}
+			return new ZipContent(this, list);
+		} catch (Exception e) {
+			throw new FallbackException("Error opening zip file: " + file.getAbsolutePath(), e);
 		}
-		return new ZipContent(this, list);
 	}
 
 	private boolean isValidEntry(IZipEntry zipEntry) {
@@ -98,12 +104,8 @@ public class FallbackZipParser implements IZipParser {
 
 	@Override
 	public void close() throws IOException {
-		try {
+		if (zipFile != null) {
-			if (zipFile != null) {
+			zipFile.close();
-				zipFile.close();
-			}
-		} finally {
-			zipFile = null;
 		}
 	}
 }

jadx-commons/jadx-zip/src/main/java/jadx/zip/io/ByteBufferBackedInputStream.java

@@ -12,6 +12,7 @@ public class ByteBufferBackedInputStream extends InputStream {
 		this.buf = buf;
 	}
 
+	@Override
 	public int read() throws IOException {
 		if (!buf.hasRemaining()) {
 			return -1;
@@ -19,6 +20,7 @@ public class ByteBufferBackedInputStream extends InputStream {
 		return buf.get() & 0xFF;
 	}
 
+	@Override
 	@SuppressWarnings("NullableProblems")
 	public int read(byte[] bytes, int off, int len) throws IOException {
 		if (!buf.hasRemaining()) {

jadx-commons/jadx-zip/src/main/java/jadx/zip/parser/JadxZipEntry.java

@@ -35,6 +35,7 @@ public final class JadxZipEntry implements IZipEntry {
 		return compressedSize <= uncompressedSize;
 	}
 
+	@Override
 	public String getName() {
 		return fileName;
 	}

jadx-commons/jadx-zip/src/main/java/jadx/zip/parser/JadxZipParser.java

@@ -49,9 +49,9 @@ public final class JadxZipParser implements IZipParser {
 	private final boolean verify;
 	private final boolean useLimitedDataStream;
 
-	private RandomAccessFile file;
+	private @Nullable RandomAccessFile file;
-	private FileChannel fileChannel;
+	private @Nullable FileChannel fileChannel;
-	private ByteBuffer byteBuffer;
+	private @Nullable ByteBuffer byteBuffer;
 
 	private int endOfCDStart = -2;
 
@@ -90,23 +90,25 @@ public final class JadxZipParser implements IZipParser {
 		}
 	}
 
-	@SuppressWarnings("RedundantIfStatement")
 	public boolean canOpen() {
 		try {
 			load();
 			int eocdStart = searchEndOfCDStart();
-			ByteBuffer buf = byteBuffer;
+			ByteBuffer buf = getBuffer();
 			buf.position(eocdStart + 4);
 			int diskNum = readU2(buf);
-			if (diskNum == 0xFFFF) {
+			if (diskNum != 0xFFFF) { // Zip64 not supported
-				// Zip64
+				return true;
-				return false;
 			}
-			return true;
 		} catch (Exception e) {
 			LOG.warn("Jadx parser can't open zip file: {}", zipFile, e);
-			return false;
 		}
+		try {
+			close();
+		} catch (Exception e) {
+			LOG.warn("Failed to close jadx parser, zip file: {}", zipFile, e);
+		}
+		return false;
 	}
 
 	private boolean isValidEntry(JadxZipEntry zipEntry) {
@@ -117,13 +119,21 @@ public final class JadxZipParser implements IZipParser {
 		return validEntry;
 	}
 
+	private ByteBuffer getBuffer() {
+		ByteBuffer buf = byteBuffer;
+		if (buf == null) {
+			throw new RuntimeException("File not opened: " + zipFile);
+		}
+		return buf;
+	}
+
 	private void load() throws IOException {
 		if (byteBuffer != null) {
 			// already loaded
 			return;
 		}
-		file = new RandomAccessFile(zipFile, "r");
+		RandomAccessFile raFile = new RandomAccessFile(zipFile, "r");
-		long size = file.length();
+		long size = raFile.length();
 		if (size >= Integer.MAX_VALUE) {
 			throw new IOException("Zip file is too big");
 		}
@@ -131,16 +141,16 @@ public final class JadxZipParser implements IZipParser {
 		if (fileLen < 100 * 1024 * 1024) {
 			// load files smaller than 100MB directly into memory
 			byte[] bytes = new byte[fileLen];
-			file.readFully(bytes);
+			raFile.readFully(bytes);
-			byteBuffer = ByteBuffer.wrap(bytes).asReadOnlyBuffer();
+			byteBuffer = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
-			file.close();
+			raFile.close();
-			file = null;
 		} else {
 			// for big files - use a memory mapped file
-			fileChannel = file.getChannel();
+			file = raFile;
+			fileChannel = raFile.getChannel();
 			byteBuffer = fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileChannel.size());
+			byteBuffer.order(ByteOrder.LITTLE_ENDIAN);
 		}
-		byteBuffer.order(ByteOrder.LITTLE_ENDIAN);
 	}
 
 	private List<IZipEntry> searchLocalFileHeaders(int maxEntriesCount) {
@@ -165,7 +175,7 @@ public final class JadxZipParser implements IZipParser {
 		if (eocdStart < 0) {
 			throw new RuntimeException("End of central directory not found");
 		}
-		ByteBuffer buf = byteBuffer;
+		ByteBuffer buf = getBuffer();
 		buf.position(eocdStart + 10);
 		int entriesCount = readU2(buf);
 		buf.position(eocdStart + 16);
@@ -186,7 +196,7 @@ public final class JadxZipParser implements IZipParser {
 	}
 
 	private JadxZipEntry loadCDEntry() {
-		ByteBuffer buf = byteBuffer;
+		ByteBuffer buf = getBuffer();
 		int start = buf.position();
 		buf.position(start + 28);
 		int fileNameLen = readU2(buf);
@@ -207,7 +217,7 @@ public final class JadxZipParser implements IZipParser {
 	}
 
 	private JadxZipEntry fixEntryFromCD(JadxZipEntry entry, int start) {
-		ByteBuffer buf = byteBuffer;
+		ByteBuffer buf = getBuffer();
 		buf.position(start + 10);
 		int comprMethod = readU2(buf);
 		buf.position(start + 20);
@@ -237,7 +247,7 @@ public final class JadxZipParser implements IZipParser {
 	}
 
 	private JadxZipEntry loadFileEntry(int start) {
-		ByteBuffer buf = byteBuffer;
+		ByteBuffer buf = getBuffer();
 		buf.position(start + 8);
 		int comprMethod = readU2(buf);
 		buf.position(start + 18);
@@ -255,7 +265,7 @@ public final class JadxZipParser implements IZipParser {
 		if (endOfCDStart != -2) {
 			return endOfCDStart;
 		}
-		ByteBuffer buf = byteBuffer;
+		ByteBuffer buf = getBuffer();
 		int pos = buf.limit() - 22;
 		int minPos = Math.max(0, pos - 0xffff);
 		while (true) {
@@ -273,7 +283,7 @@ public final class JadxZipParser implements IZipParser {
 	}
 
 	private int searchEntryStart() {
-		ByteBuffer buf = byteBuffer;
+		ByteBuffer buf = getBuffer();
 		while (true) {
 			int start = buf.position();
 			if (start + 4 > buf.limit()) {
@@ -297,14 +307,14 @@ public final class JadxZipParser implements IZipParser {
 		InputStream stream;
 		if (entry.getCompressMethod() == 8) {
 			try {
-				stream = ZipDeflate.decompressEntryToStream(byteBuffer, entry);
+				stream = ZipDeflate.decompressEntryToStream(getBuffer(), entry);
 			} catch (Exception e) {
 				entryParseFailed(entry, e);
 				return useFallbackParser(entry).getInputStream();
 			}
 		} else {
 			// treat any other compression methods values as UNCOMPRESSED
-			stream = bufferToStream(byteBuffer, entry.getDataStart(), (int) entry.getUncompressedSize());
+			stream = bufferToStream(getBuffer(), entry.getDataStart(), (int) entry.getUncompressedSize());
 		}
 		if (useLimitedDataStream) {
 			return new LimitedInputStream(stream, entry.getUncompressedSize());
@@ -318,14 +328,14 @@ public final class JadxZipParser implements IZipParser {
 		}
 		if (entry.getCompressMethod() == 8) {
 			try {
-				return ZipDeflate.decompressEntryToBytes(byteBuffer, entry);
+				return ZipDeflate.decompressEntryToBytes(getBuffer(), entry);
 			} catch (Exception e) {
 				entryParseFailed(entry, e);
 				return useFallbackParser(entry).getBytes();
 			}
 		}
 		// treat any other compression methods values as UNCOMPRESSED
-		return bufferToBytes(byteBuffer, entry.getDataStart(), (int) entry.getUncompressedSize());
+		return bufferToBytes(getBuffer(), entry.getDataStart(), (int) entry.getUncompressedSize());
 	}
 
 	private static void verifyEntry(JadxZipEntry entry) {
@@ -361,7 +371,7 @@ public final class JadxZipParser implements IZipParser {
 	}
 
 	@SuppressWarnings("resource")
-	private ZipContent initFallbackParser() {
+	private synchronized ZipContent initFallbackParser() {
 		if (fallbackZipContent == null) {
 			try {
 				fallbackZipContent = new FallbackZipParser(zipFile, options).open();
@@ -378,7 +388,7 @@ public final class JadxZipParser implements IZipParser {
 	}
 
 	private int readFlags(JadxZipEntry entry) {
-		ByteBuffer buf = byteBuffer;
+		ByteBuffer buf = getBuffer();
 		buf.position(entry.getEntryStart() + 6);
 		return readU2(buf);
 	}
@@ -407,6 +417,7 @@ public final class JadxZipParser implements IZipParser {
 		return new String(bytes, StandardCharsets.UTF_8);
 	}
 
+	@SuppressWarnings("DataFlowIssue")
 	@Override
 	public void close() throws IOException {
 		try {

jadx-core/src/main/java/jadx/api/JadxArgs.java

@@ -95,7 +95,7 @@ public class JadxArgs implements Closeable {
 	/**
 	 * Predicate that allows to filter the classes to be process based on their full name
 	 */
-	private Predicate<String> classFilter = null;
+	private @Nullable Predicate<String> classFilter = null;
 
 	/**
 	 * Save dependencies for classes accepted by {@code classFilter}
@@ -227,7 +227,6 @@ public class JadxArgs implements Closeable {
 	@Override
 	public void close() {
 		try {
-			inputFiles = null;
 			if (codeCache != null) {
 				codeCache.close();
 			}
@@ -239,9 +238,6 @@ public class JadxArgs implements Closeable {
 			}
 		} catch (Exception e) {
 			LOG.error("Failed to close JadxArgs", e);
-		} finally {
-			codeCache = null;
-			usageInfoCache = null;
 		}
 	}
 

jadx-core/src/main/java/jadx/api/JavaClass.java

@@ -6,12 +6,11 @@ import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import jadx.api.metadata.ICodeAnnotation;
 import jadx.api.metadata.ICodeNodeRef;
@@ -26,11 +25,9 @@ import jadx.core.dex.nodes.MethodNode;
 import jadx.core.utils.ListUtils;
 
 public final class JavaClass implements JavaNode {
-	private static final Logger LOG = LoggerFactory.getLogger(JavaClass.class);
+	private final @Nullable JadxDecompiler decompiler;
-
-	private final JadxDecompiler decompiler;
 	private final ClassNode cls;
-	private final JavaClass parent;
+	private final @Nullable JavaClass parent;
 
 	private List<JavaClass> innerClasses = Collections.emptyList();
 	private List<JavaClass> inlinedClasses = Collections.emptyList();
@@ -38,7 +35,7 @@ public final class JavaClass implements JavaNode {
 	private List<JavaMethod> methods = Collections.emptyList();
 	private boolean listsLoaded;
 
-	JavaClass(ClassNode classNode, JadxDecompiler decompiler) {
+	JavaClass(ClassNode classNode, @NotNull JadxDecompiler decompiler) {
 		this.decompiler = decompiler;
 		this.cls = classNode;
 		this.parent = null;
@@ -47,7 +44,7 @@ public final class JavaClass implements JavaNode {
 	/**
 	 * Inner classes constructor
 	 */
-	JavaClass(ClassNode classNode, JavaClass parent) {
+	JavaClass(ClassNode classNode, @NotNull JavaClass parent) {
 		this.decompiler = null;
 		this.cls = classNode;
 		this.parent = parent;
@@ -69,6 +66,21 @@ public final class JavaClass implements JavaNode {
 		load();
 	}
 
+	/**
+	 * Detect if calling load() would trigger a potentially expensive decompilation operation.
+	 */
+	public boolean loadingWouldRequireDecompilation() {
+		if (listsLoaded) {
+			// lists are already populated, so it's safe regardless of the state of the class itself
+			return false;
+		}
+		if (cls.getState().isProcessComplete()) {
+			// decompilation has already finished
+			return false;
+		}
+		return true;
+	}
+
 	public synchronized ICodeInfo reload() {
 		listsLoaded = false;
 		return cls.reloadCode();
@@ -187,10 +199,10 @@ public final class JavaClass implements JavaNode {
 		if (parent != null) {
 			return parent.getRootDecompiler();
 		}
-		return decompiler;
+		return Objects.requireNonNull(decompiler);
 	}
 
-	public ICodeAnnotation getAnnotationAt(int pos) {
+	public @Nullable ICodeAnnotation getAnnotationAt(int pos) {
 		return getCodeInfo().getCodeMetadata().getAt(pos);
 	}
 
@@ -259,7 +271,7 @@ public final class JavaClass implements JavaNode {
 	}
 
 	@Override
-	public JavaClass getDeclaringClass() {
+	public @Nullable JavaClass getDeclaringClass() {
 		return parent;
 	}
 
@@ -362,21 +374,4 @@ public final class JavaClass implements JavaNode {
 	public String toString() {
 		return getFullName();
 	}
-
-	/**
-	 * Detect if calling load() would trigger a potentially expensive decompilation operation.
-	 */
-	public boolean loadingWouldRequireDecompilation() {
-		if (listsLoaded) {
-			// lists are already poplulated, so it's safe regardless of the state of the class itself
-			return false;
-		}
-
-		if (cls.getState().isProcessComplete()) {
-			// decompilation has already finished
-			return false;
-		}
-
-		return true;
-	}
 }

jadx-core/src/main/java/jadx/api/JavaMethod.java

@@ -5,8 +5,6 @@ import java.util.List;
 import java.util.stream.Collectors;
 
 import org.jetbrains.annotations.ApiStatus;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import jadx.api.metadata.ICodeAnnotation;
 import jadx.api.metadata.ICodeNodeRef;
@@ -19,8 +17,6 @@ import jadx.core.dex.nodes.MethodNode;
 import jadx.core.utils.Utils;
 
 public final class JavaMethod implements JavaNode {
-	private static final Logger LOG = LoggerFactory.getLogger(JavaMethod.class);
-
 	private final MethodNode mth;
 	private final JavaClass parent;
 

jadx-core/src/main/java/jadx/core/dex/info/ConstStorage.java

@@ -15,7 +15,6 @@ import jadx.core.dex.nodes.ClassNode;
 import jadx.core.dex.nodes.FieldNode;
 import jadx.core.dex.nodes.IFieldInfoRef;
 import jadx.core.dex.nodes.RootNode;
-import jadx.core.dex.visitors.prepare.CollectConstValues;
 
 public class ConstStorage {
 
@@ -23,18 +22,18 @@ public class ConstStorage {
 		private final Map<Object, IFieldInfoRef> values = new ConcurrentHashMap<>();
 		private final Set<Object> duplicates = new HashSet<>();
 
-		public Map<Object, IFieldInfoRef> getValues() {
+		Map<Object, IFieldInfoRef> getValues() {
 			return values;
 		}
 
-		public IFieldInfoRef get(Object key) {
+		IFieldInfoRef get(Object key) {
 			return values.get(key);
 		}
 
 		/**
 		 * @return true if this value is duplicated
 		 */
-		public boolean put(Object value, IFieldInfoRef fld) {
+		boolean put(Object value, IFieldInfoRef fld) {
 			if (duplicates.contains(value)) {
 				values.remove(value);
 				return true;
@@ -85,14 +84,6 @@ public class ConstStorage {
 		globalValues.put(value, fld);
 	}
 
-	/**
-	 * Use method from CollectConstValues class
-	 */
-	@Deprecated
-	public static @Nullable Object getFieldConstValue(FieldNode fld) {
-		return CollectConstValues.getFieldConstValue(fld);
-	}
-
 	public void removeForClass(ClassNode cls) {
 		classes.remove(cls);
 		globalValues.removeForCls(cls);

jadx-core/src/main/java/jadx/core/dex/instructions/args/ArgType.java

@@ -10,6 +10,8 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.annotations.TestOnly;
 
+import com.google.errorprone.annotations.Immutable;
+
 import jadx.core.Consts;
 import jadx.core.dex.info.ClassInfo;
 import jadx.core.dex.nodes.RootNode;
@@ -18,6 +20,7 @@ import jadx.core.utils.ListUtils;
 import jadx.core.utils.Utils;
 import jadx.core.utils.exceptions.JadxRuntimeException;
 
+@Immutable
 public abstract class ArgType {
 	public static final ArgType INT = primitive(PrimitiveType.INT);
 	public static final ArgType BOOLEAN = primitive(PrimitiveType.BOOLEAN);
@@ -200,7 +203,7 @@ public abstract class ArgType {
 	private static final class PrimitiveArg extends KnownType {
 		private final PrimitiveType type;
 
-		public PrimitiveArg(PrimitiveType type) {
+		PrimitiveArg(PrimitiveType type) {
 			this.type = type;
 			this.hash = type.hashCode();
 		}
@@ -229,7 +232,7 @@ public abstract class ArgType {
 	private static class ObjectType extends KnownType {
 		protected final String objName;
 
-		public ObjectType(String obj) {
+		ObjectType(String obj) {
 			this.objName = obj;
 			this.hash = objName.hashCode();
 		}
@@ -263,15 +266,15 @@ public abstract class ArgType {
 	private static final class GenericType extends ObjectType {
 		private List<ArgType> extendTypes;
 
-		public GenericType(String obj) {
+		GenericType(String obj) {
 			this(obj, Collections.emptyList());
 		}
 
-		public GenericType(String obj, ArgType extendType) {
+		GenericType(String obj, ArgType extendType) {
 			this(obj, Collections.singletonList(extendType));
 		}
 
-		public GenericType(String obj, List<ArgType> extendTypes) {
+		GenericType(String obj, List<ArgType> extendTypes) {
 			super(obj);
 			this.extendTypes = extendTypes;
 		}
@@ -337,7 +340,7 @@ public abstract class ArgType {
 		private final ArgType type;
 		private final WildcardBound bound;
 
-		public WildcardType(ArgType obj, WildcardBound bound) {
+		WildcardType(ArgType obj, WildcardBound bound) {
 			super(OBJECT.getObject());
 			this.type = Objects.requireNonNull(obj);
 			this.bound = Objects.requireNonNull(bound);
@@ -382,7 +385,7 @@ public abstract class ArgType {
 	private static class GenericObject extends ObjectType {
 		private final List<ArgType> generics;
 
-		public GenericObject(String obj, List<ArgType> generics) {
+		GenericObject(String obj, List<ArgType> generics) {
 			super(obj);
 			this.generics = Objects.requireNonNull(generics);
 			this.hash = calcHash();
@@ -418,7 +421,7 @@ public abstract class ArgType {
 		private final ObjectType outerType;
 		private final ObjectType innerType;
 
-		public OuterGenericObject(ObjectType outerType, ObjectType innerType) {
+		OuterGenericObject(ObjectType outerType, ObjectType innerType) {
 			super(outerType.getObject() + '$' + innerType.getObject());
 			this.outerType = outerType;
 			this.innerType = innerType;
@@ -466,7 +469,7 @@ public abstract class ArgType {
 		private static final PrimitiveType[] ARRAY_POSSIBLES = new PrimitiveType[] { PrimitiveType.ARRAY };
 		private final ArgType arrayElement;
 
-		public ArrayArg(ArgType arrayElement) {
+		ArrayArg(ArgType arrayElement) {
 			this.arrayElement = arrayElement;
 			this.hash = arrayElement.hashCode();
 		}
@@ -526,7 +529,7 @@ public abstract class ArgType {
 	private static final class UnknownArg extends ArgType {
 		private final PrimitiveType[] possibleTypes;
 
-		public UnknownArg(PrimitiveType[] types) {
+		UnknownArg(PrimitiveType[] types) {
 			this.possibleTypes = types;
 			this.hash = Arrays.hashCode(possibleTypes);
 		}

jadx-core/src/main/java/jadx/core/dex/nodes/MethodNode.java

@@ -74,7 +74,7 @@ public class MethodNode extends NotificationAttrNode implements IMethodDetails,
 	// decompilation data, reset on unload
 	private RegisterArg thisArg;
 	private List<RegisterArg> argsList;
-	private InsnNode[] instructions;
+	private @Nullable InsnNode[] instructions;
 	private List<BlockNode> blocks;
 	private int blocksMaxCId;
 	private BlockNode enterBlock;
@@ -106,11 +106,12 @@ public class MethodNode extends NotificationAttrNode implements IMethodDetails,
 		this.parentClass = classNode;
 		this.accFlags = new AccessInfo(mthData.getAccessFlags(), AFType.METHOD);
 		ICodeReader codeReader = mthData.getCodeReader();
-		this.noCode = codeReader == null;
+		if (codeReader == null) {
-		if (noCode) {
+			this.noCode = true;
 			this.codeReader = null;
 			this.insnsCount = 0;
 		} else {
+			this.noCode = false;
 			this.codeReader = codeReader.copy();
 			this.insnsCount = codeReader.getUnitsCount();
 		}
@@ -713,6 +714,7 @@ public class MethodNode extends NotificationAttrNode implements IMethodDetails,
 	}
 
 	// Cannot modify through get, use setUseIn
+	@Override
 	public List<MethodNode> getUseIn() {
 		return Collections.unmodifiableList(useIn);
 	}
@@ -721,7 +723,7 @@ public class MethodNode extends NotificationAttrNode implements IMethodDetails,
 	public void setUseIn(List<MethodNode> useIn) {
 		this.useIn = useIn;
 
-		// Notify all methods (callers) this method (calee) is used in
+		// Notify all methods (callers) this method (callee) is used in
 		for (MethodNode methodUsedIn : useIn) {
 			methodUsedIn.addUsed(this);
 		}

jadx-core/src/main/java/jadx/core/utils/StringUtils.java

@@ -209,7 +209,7 @@ public class StringUtils {
 		return sb.toString();
 	}
 
-	private static String escapeXmlChar(char c) {
+	private static @Nullable String escapeXmlChar(char c) {
 		if (c <= 0x1F) {
 			return "\\" + (int) c;
 		}
@@ -231,7 +231,7 @@ public class StringUtils {
 		}
 	}
 
-	private static String escapeWhiteSpaceChar(char c) {
+	private static @Nullable String escapeWhiteSpaceChar(char c) {
 		switch (c) {
 			case '\n':
 				return "\\n";

jadx-core/src/main/java/jadx/core/utils/Utils.java

@@ -3,6 +3,7 @@ package jadx.core.utils;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.io.StringWriter;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -295,7 +296,7 @@ public class Utils {
 				}
 			}
 		};
-		try (PrintWriter pw = new PrintWriter(w, true)) {
+		try (PrintWriter pw = new PrintWriter(w, true, StandardCharsets.UTF_8)) {
 			filterRecursive(throwable);
 			throwable.printStackTrace(pw);
 			pw.flush();
@@ -618,7 +619,7 @@ public class Utils {
 		private final AtomicInteger number = new AtomicInteger(0);
 		private final String name;
 
-		public SimpleThreadFactory(String name) {
+		SimpleThreadFactory(String name) {
 			this.name = name;
 		}
 

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/IMethodHandle.java

@@ -1,11 +1,15 @@
 package jadx.api.plugins.input.data;
 
+import org.jetbrains.annotations.Nullable;
+
 public interface IMethodHandle {
 
 	MethodHandleType getType();
 
+	@Nullable
 	IFieldRef getFieldRef();
 
+	@Nullable
 	IMethodRef getMethodRef();
 
 	void load();

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/annotations/EncodedValue.java

@@ -8,7 +8,7 @@ import jadx.api.plugins.input.data.attributes.JadxAttrType;
 import jadx.api.plugins.input.data.attributes.PinnedAttribute;
 
 public class EncodedValue extends PinnedAttribute {
-	public static final EncodedValue NULL = new EncodedValue(EncodedType.ENCODED_NULL, null);
+	public static final EncodedValue NULL = new EncodedValue(EncodedType.ENCODED_NULL, "null");
 
 	private final EncodedType type;
 	private final Object value;

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/annotations/IAnnotation.java

@@ -11,8 +11,7 @@ public interface IAnnotation {
 
 	Map<String, EncodedValue> getValues();
 
-	@Nullable
+	default @Nullable EncodedValue getDefaultValue() {
-	default EncodedValue getDefaultValue() {
 		return getValues().get("value");
 	}
 }

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/attributes/types/AnnotationMethodParamsAttr.java

@@ -11,8 +11,7 @@ import jadx.api.plugins.input.data.attributes.PinnedAttribute;
 
 public class AnnotationMethodParamsAttr extends PinnedAttribute {
 
-	@Nullable
+	public static @Nullable AnnotationMethodParamsAttr pack(List<List<IAnnotation>> annotationRefList) {
-	public static AnnotationMethodParamsAttr pack(List<List<IAnnotation>> annotationRefList) {
 		if (annotationRefList.isEmpty()) {
 			return null;
 		}

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/attributes/types/AnnotationsAttr.java

@@ -16,8 +16,7 @@ import jadx.api.plugins.input.data.attributes.PinnedAttribute;
 
 public class AnnotationsAttr extends PinnedAttribute {
 
-	@Nullable
+	public static @Nullable AnnotationsAttr pack(List<IAnnotation> annotationList) {
-	public static AnnotationsAttr pack(List<IAnnotation> annotationList) {
 		if (annotationList.isEmpty()) {
 			return null;
 		}
@@ -39,7 +38,7 @@ public class AnnotationsAttr extends PinnedAttribute {
 		this.map = map;
 	}
 
-	public IAnnotation get(String className) {
+	public @Nullable IAnnotation get(String className) {
 		return map.get(className);
 	}
 

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/attributes/types/MethodParametersAttr.java

@@ -27,6 +27,7 @@ public class MethodParametersAttr extends PinnedAttribute {
 			return name;
 		}
 
+		@Override
 		public String toString() {
 			return AccessFlags.format(accFlags, AccessFlagsScope.METHOD) + name;
 		}

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/impl/FieldRefHandle.java

@@ -1,5 +1,7 @@
 package jadx.api.plugins.input.data.impl;
 
+import org.jetbrains.annotations.Nullable;
+
 import jadx.api.plugins.input.data.IFieldRef;
 import jadx.api.plugins.input.data.IMethodHandle;
 import jadx.api.plugins.input.data.IMethodRef;
@@ -21,12 +23,12 @@ public class FieldRefHandle implements IMethodHandle {
 	}
 
 	@Override
-	public IFieldRef getFieldRef() {
+	public @Nullable IFieldRef getFieldRef() {
 		return fieldRef;
 	}
 
 	@Override
-	public IMethodRef getMethodRef() {
+	public @Nullable IMethodRef getMethodRef() {
 		return null;
 	}
 

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/impl/ListConsumer.java

@@ -9,7 +9,7 @@ import jadx.api.plugins.input.data.ISeqConsumer;
 
 public class ListConsumer<T, R> implements ISeqConsumer<T> {
 	private final Function<T, R> convert;
-	private List<R> list;
+	private List<R> list = new ArrayList<>();
 
 	public ListConsumer(Function<T, R> convert) {
 		this.convert = convert;
@@ -26,10 +26,6 @@ public class ListConsumer<T, R> implements ISeqConsumer<T> {
 	}
 
 	public List<R> getResult() {
-		if (list == null) {
-			// init not called
-			return Collections.emptyList();
-		}
 		return list;
 	}
 }

jadx-plugins/jadx-input-api/src/main/java/jadx/api/plugins/input/data/impl/MethodRefHandle.java

@@ -1,5 +1,7 @@
 package jadx.api.plugins.input.data.impl;
 
+import org.jetbrains.annotations.Nullable;
+
 import jadx.api.plugins.input.data.IFieldData;
 import jadx.api.plugins.input.data.IMethodHandle;
 import jadx.api.plugins.input.data.IMethodRef;
@@ -21,12 +23,12 @@ public class MethodRefHandle implements IMethodHandle {
 	}
 
 	@Override
-	public IMethodRef getMethodRef() {
+	public @Nullable IMethodRef getMethodRef() {
 		return methodRef;
 	}
 
 	@Override
-	public IFieldData getFieldRef() {
+	public @Nullable IFieldData getFieldRef() {
 		return null;
 	}