style: use character instead of string, for better performance (PR #503)

jadx-cli/src/main/java/jadx/cli/JCommanderWrapper.java

@@ -90,7 +90,7 @@ public class JCommanderWrapper<T> {
 		if (fieldType == int.class) {
 			try {
 				int val = f.getInt(args);
-				opt.append(" (default: ").append(val).append(")");
+				opt.append(" (default: ").append(val).append(')');
 			} catch (Exception e) {
 				// ignore
 			}

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

@@ -57,6 +57,6 @@ public final class CodePosition {
 
 	@Override
 	public String toString() {
-		return line + ":" + offset + (node != null ? " " + node : "");
+		return line + ':' + offset + (node != null ? " " + node : "");
 	}
 }

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

@@ -77,7 +77,7 @@ public class JadxArgsValidator {
 		if (pos != -1) {
 			outDirName = name.substring(0, pos);
 		} else {
-			outDirName = name + "-" + JadxArgs.DEFAULT_OUT_DIR;
+			outDirName = name + '-' + JadxArgs.DEFAULT_OUT_DIR;
 		}
 		LOG.info("output directory: {}", outDirName);
 		outDir = new File(outDirName);

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

@@ -21,7 +21,7 @@ public final class JavaField implements JavaNode {
 
 	@Override
 	public String getFullName() {
-		return parent.getFullName() + "." + getName();
+		return parent.getFullName() + '.' + getName();
 	}
 
 	@Override

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

@@ -70,6 +70,6 @@ public class ResourceFile {
 
 	@Override
 	public String toString() {
-		return "ResourceFile{name='" + name + '\'' + ", type=" + type + "}";
+		return "ResourceFile{name='" + name + '\'' + ", type=" + type + '}';
 	}
 }

jadx-core/src/main/java/jadx/core/clsp/ClsSet.java

@@ -113,7 +113,7 @@ public class ClsSet {
 			} else if (outputName.endsWith(".jar")) {
 				ZipOutputStream out = new ZipOutputStream(outputStream);
 				try {
-					out.putNextEntry(new ZipEntry(CLST_PKG_PATH + "/" + CLST_FILENAME));
+					out.putNextEntry(new ZipEntry(CLST_PKG_PATH + '/' + CLST_FILENAME));
 					save(out);
 				} finally {
 					close(out);

jadx-core/src/main/java/jadx/core/codegen/AnnotationGen.java

@@ -164,7 +164,7 @@ public class AnnotationGen {
 			formatAnnotation(code, (Annotation) val);
 		} else {
 			// TODO: also can be method values
-			throw new JadxRuntimeException("Can't decode value: " + val + " (" + val.getClass() + ")");
+			throw new JadxRuntimeException("Can't decode value: " + val + " (" + val.getClass() + ')');
 		}
 	}
 

jadx-core/src/main/java/jadx/core/codegen/ClassGen.java

@@ -535,7 +535,7 @@ public class ClassGen {
 					&& importCls.getShortName().equals(shortName)) {
 				if (extClsInfo.isInner()) {
 					String parent = useClassInternal(useCls, extClsInfo.getParentClass().getAlias());
-					return parent + "." + shortName;
+					return parent + '.' + shortName;
 				} else {
 					return fullName;
 				}

jadx-core/src/main/java/jadx/core/codegen/InsnGen.java

@@ -509,12 +509,12 @@ public class InsnGen {
 			case PHI:
 			case MERGE:
 				fallbackOnlyInsn(insn);
-				code.add(insn.getType().toString()).add("(");
+				code.add(insn.getType().toString()).add('(');
 				for (InsnArg insnArg : insn.getArguments()) {
 					addArg(code, insnArg);
 					code.add(' ');
 				}
-				code.add(")");
+				code.add(')');
 				break;
 
 			default:

jadx-core/src/main/java/jadx/core/codegen/MethodGen.java

@@ -175,9 +175,9 @@ public class MethodGen {
 
 			code.startLine("throw new UnsupportedOperationException(\"Method not decompiled: ")
 					.add(clsAlias.makeFullClsName(clsAlias.getShortName(), true))
-					.add(".")
+					.add('.')
 					.add(mth.getAlias())
-					.add("(")
+					.add('(')
 					.add(Utils.listToString(mth.getMethodInfo().getArgumentsTypes()))
 					.add("):")
 					.add(mth.getMethodInfo().getReturnType().toString())
@@ -219,7 +219,7 @@ public class MethodGen {
 			}
 			if (addLabels && (insn.contains(AType.JUMP) || insn.contains(AType.EXC_HANDLER))) {
 				code.decIndent();
-				code.startLine(getLabelName(insn.getOffset()) + ":");
+				code.startLine(getLabelName(insn.getOffset()) + ':');
 				code.incIndent();
 			}
 			try {

jadx-core/src/main/java/jadx/core/codegen/NameGen.java

@@ -109,7 +109,7 @@ public class NameGen {
 		String name = arg.getName();
 		String varName = name != null ? name : guessName(arg);
 		if (NameMapper.isReserved(varName)) {
-			return varName + "R";
+			return varName + 'R';
 		}
 		return varName;
 	}

jadx-core/src/main/java/jadx/core/codegen/TypeGen.java

@@ -128,7 +128,7 @@ public class TypeGen {
 		}
 		String str = Long.toString(l);
 		if (Math.abs(l) >= Integer.MAX_VALUE) {
-			str += "L";
+			str += 'L';
 		}
 		return str;
 	}
@@ -152,7 +152,7 @@ public class TypeGen {
 		if (d == Double.MIN_NORMAL) {
 			return "Double.MIN_NORMAL";
 		}
-		return Double.toString(d) + "d";
+		return Double.toString(d) + 'd';
 	}
 
 	public static String formatFloat(float f) {
@@ -174,6 +174,6 @@ public class TypeGen {
 		if (f == Float.MIN_NORMAL) {
 			return "Float.MIN_NORMAL";
 		}
-		return Float.toString(f) + "f";
+		return Float.toString(f) + 'f';
 	}
 }

jadx-core/src/main/java/jadx/core/deobf/Deobfuscator.java

@@ -394,7 +394,7 @@ public class Deobfuscator {
 				return null;
 			}
 		}
-		ClassNode otherCls = cls.dex().root().searchClassByName(cls.getPackage() + "." + name);
+		ClassNode otherCls = cls.dex().root().searchClassByName(cls.getPackage() + '.' + name);
 		if (otherCls != null) {
 			return null;
 		}
@@ -484,7 +484,7 @@ public class Deobfuscator {
 
 	private String prepareNamePart(String name) {
 		if (name.length() > maxLength) {
-			return "x" + Integer.toHexString(name.hashCode());
+			return 'x' + Integer.toHexString(name.hashCode());
 		}
 		return NameMapper.removeInvalidCharsMiddle(name);
 	}

jadx-core/src/main/java/jadx/core/dex/attributes/AttributeStorage.java

@@ -121,6 +121,6 @@ public class AttributeStorage {
 		if (list.isEmpty()) {
 			return "";
 		}
-		return "A:{" + Utils.listToString(list) + "}";
+		return "A:{" + Utils.listToString(list) + '}';
 	}
 }

jadx-core/src/main/java/jadx/core/dex/attributes/annotations/Annotation.java

@@ -42,6 +42,6 @@ public class Annotation {
 
 	@Override
 	public String toString() {
-		return "Annotation[" + visibility + ", " + atype + ", " + values + "]";
+		return "Annotation[" + visibility + ", " + atype + ", " + values + ']';
 	}
 }

jadx-core/src/main/java/jadx/core/dex/attributes/nodes/EdgeInsnAttr.java

@@ -43,6 +43,6 @@ public class EdgeInsnAttr implements IAttribute {
 
 	@Override
 	public String toString() {
-		return "EDGE_INSN: " + start + "->" + end + " " + insn;
+		return "EDGE_INSN: " + start + "->" + end + ' ' + insn;
 	}
 }

jadx-core/src/main/java/jadx/core/dex/attributes/nodes/FieldReplaceAttr.java

@@ -44,6 +44,6 @@ public class FieldReplaceAttr implements IAttribute {
 
 	@Override
 	public String toString() {
-		return "REPLACE: " + replaceType + " " + replaceObj;
+		return "REPLACE: " + replaceType + ' ' + replaceObj;
 	}
 }

jadx-core/src/main/java/jadx/core/dex/attributes/nodes/JadxError.java

@@ -34,7 +34,7 @@ public class JadxError {
 		}
 		if (cause != null) {
 			str.append(cause.getClass());
-			str.append(":");
+			str.append(':');
 			str.append(cause.getMessage());
 			str.append("\n");
 			str.append(Utils.getStackTrace(cause));

jadx-core/src/main/java/jadx/core/dex/attributes/nodes/PhiListAttr.java

@@ -25,7 +25,7 @@ public class PhiListAttr implements IAttribute {
 		StringBuilder sb = new StringBuilder();
 		sb.append("PHI: ");
 		for (PhiInsn phiInsn : list) {
-			sb.append('r').append(phiInsn.getResult().getRegNum()).append(" ");
+			sb.append('r').append(phiInsn.getResult().getRegNum()).append(' ');
 		}
 		return sb.toString();
 	}

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

@@ -203,6 +203,6 @@ public class AccessInfo {
 
 	@Override
 	public String toString() {
-		return "AccessInfo: " + type + " 0x" + Integer.toHexString(accFlags) + " (" + rawString() + ")";
+		return "AccessInfo: " + type + " 0x" + Integer.toHexString(accFlags) + " (" + rawString() + ')';
 	}
 }

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

@@ -91,7 +91,7 @@ public final class ClassInfo implements Comparable<ClassInfo> {
 
 		int sep = clsName.lastIndexOf('$');
 		if (canBeInner && sep > 0 && sep != clsName.length() - 1) {
-			String parClsName = pkg + "." + clsName.substring(0, sep);
+			String parClsName = pkg + '.' + clsName.substring(0, sep);
 			if (pkg.isEmpty()) {
 				parClsName = clsName.substring(0, sep);
 			}
@@ -110,7 +110,7 @@ public final class ClassInfo implements Comparable<ClassInfo> {
 			String innerSep = raw ? "$" : ".";
 			return parentClass.makeFullClsName(parentClass.getShortName(), raw) + innerSep + shortName;
 		}
-		return pkg.isEmpty() ? shortName : pkg + "." + shortName;
+		return pkg.isEmpty() ? shortName : pkg + '.' + shortName;
 	}
 
 	public String makeRawFullName() {
@@ -148,7 +148,7 @@ public final class ClassInfo implements Comparable<ClassInfo> {
 		if (parentClass == null) {
 			return name;
 		}
-		return parentClass.getNameWithoutPackage() + "." + name;
+		return parentClass.getNameWithoutPackage() + '.' + name;
 	}
 
 	public ClassInfo getParentClass() {

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

@@ -54,11 +54,11 @@ public final class FieldInfo {
 	}
 
 	public String getFullId() {
-		return declClass.getFullName() + "." + name + ":" + TypeGen.signature(type);
+		return declClass.getFullName() + '.' + name + ':' + TypeGen.signature(type);
 	}
 
 	public String getRawFullId() {
-		return declClass.makeRawFullName() + "." + name + ":" + TypeGen.signature(type);
+		return declClass.makeRawFullName() + '.' + name + ':' + TypeGen.signature(type);
 	}
 
 	public boolean isRenamed() {
@@ -93,6 +93,6 @@ public final class FieldInfo {
 
 	@Override
 	public String toString() {
-		return declClass + "." + name + " " + type;
+		return declClass + "." + name + ' ' + type;
 	}
 }

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

@@ -65,15 +65,15 @@ public final class MethodInfo {
 	}
 
 	public String getFullName() {
-		return declClass.getFullName() + "." + name;
+		return declClass.getFullName() + '.' + name;
 	}
 
 	public String getFullId() {
-		return declClass.getFullName() + "." + shortId;
+		return declClass.getFullName() + '.' + shortId;
 	}
 
 	public String getRawFullId() {
-		return declClass.makeRawFullName() + "." + shortId;
+		return declClass.makeRawFullName() + '.' + shortId;
 	}
 
 	/**
@@ -151,7 +151,7 @@ public final class MethodInfo {
 
 	@Override
 	public String toString() {
-		return declClass.getFullName() + "." + name
-				+ "(" + Utils.listToString(args) + "):" + retType;
+		return declClass.getFullName() + '.' + name
+				+ '(' + Utils.listToString(args) + "):" + retType;
 	}
 }

jadx-core/src/main/java/jadx/core/dex/instructions/ArithNode.java

@@ -76,8 +76,8 @@ public class ArithNode extends InsnNode {
 		return InsnUtils.formatOffset(offset) + ": "
 				+ InsnUtils.insnTypeToString(insnType)
 				+ getResult() + " = "
-				+ getArg(0) + " "
-				+ op.getSymbol() + " "
+				+ getArg(0) + ' '
+				+ op.getSymbol() + ' '
 				+ getArg(1);
 	}
 }

jadx-core/src/main/java/jadx/core/dex/instructions/ConstClassNode.java

@@ -35,6 +35,6 @@ public final class ConstClassNode extends InsnNode {
 
 	@Override
 	public String toString() {
-		return super.toString() + " " + clsType;
+		return super.toString() + ' ' + clsType;
 	}
 }

jadx-core/src/main/java/jadx/core/dex/instructions/ConstStringNode.java

@@ -34,6 +34,6 @@ public final class ConstStringNode extends InsnNode {
 
 	@Override
 	public String toString() {
-		return super.toString() + " \"" + str + "\"";
+		return super.toString() + " \"" + str + '"';
 	}
 }

jadx-core/src/main/java/jadx/core/dex/instructions/IfNode.java

@@ -111,7 +111,7 @@ public class IfNode extends GotoNode {
 	public String toString() {
 		return InsnUtils.formatOffset(offset) + ": "
 				+ InsnUtils.insnTypeToString(insnType)
-				+ getArg(0) + " " + op.getSymbol() + " " + getArg(1)
+				+ getArg(0) + ' ' + op.getSymbol() + ' ' + getArg(1)
 				+ "  -> " + (thenBlock != null ? thenBlock : InsnUtils.formatOffset(target));
 	}
 }

jadx-core/src/main/java/jadx/core/dex/instructions/IndexInsnNode.java

@@ -35,6 +35,6 @@ public class IndexInsnNode extends InsnNode {
 
 	@Override
 	public String toString() {
-		return super.toString() + " " + InsnUtils.indexToString(index);
+		return super.toString() + ' ' + InsnUtils.indexToString(index);
 	}
 }

jadx-core/src/main/java/jadx/core/dex/instructions/InsnDecoder.java

@@ -578,7 +578,7 @@ public class InsnDecoder {
 						InsnArg.reg(insn, 0, ArgType.UNKNOWN_OBJECT));
 
 			default:
-				throw new DecodeException("Unknown instruction: '" + OpcodeInfo.getName(insn.getOpcode()) + "'");
+				throw new DecodeException("Unknown instruction: '" + OpcodeInfo.getName(insn.getOpcode()) + '\'');
 		}
 	}
 

jadx-core/src/main/java/jadx/core/dex/instructions/InvokeNode.java

@@ -73,7 +73,7 @@ public class InvokeNode extends InsnNode implements CallMthInterface {
 				+ InsnUtils.insnTypeToString(insnType)
 				+ (getResult() == null ? "" : getResult() + " = ")
 				+ Utils.listToString(getArguments())
-				+ " " + mth
+				+ ' ' + mth
 				+ " type: " + type;
 	}
 }

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

@@ -229,7 +229,7 @@ public abstract class ArgType {
 			if (bounds == 0) {
 				return "?";
 			}
-			return "? " + (bounds == -1 ? "super" : "extends") + " " + type;
+			return "? " + (bounds == -1 ? "super" : "extends") + ' ' + type;
 		}
 	}
 
@@ -245,7 +245,7 @@ public abstract class ArgType {
 		}
 
 		public GenericObject(GenericObject outerType, String innerName, ArgType[] generics) {
-			super(outerType.getObject() + "$" + innerName);
+			super(outerType.getObject() + '$' + innerName);
 			this.outerType = outerType;
 			this.generics = generics;
 			this.hash = outerType.hashCode() + 31 * innerName.hashCode()
@@ -275,7 +275,7 @@ public abstract class ArgType {
 
 		@Override
 		public String toString() {
-			return super.toString() + "<" + Utils.arrayToString(generics) + ">";
+			return super.toString() + '<' + Utils.arrayToString(generics) + '>';
 		}
 	}
 
@@ -389,7 +389,7 @@ public abstract class ArgType {
 			if (possibleTypes.length == PrimitiveType.values().length) {
 				return "?";
 			} else {
-				return "?" + Arrays.toString(possibleTypes);
+				return '?' + Arrays.toString(possibleTypes);
 			}
 		}
 	}

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

@@ -70,6 +70,6 @@ public final class FieldArg extends RegisterArg {
 
 	@Override
 	public String toString() {
-		return "(" + field + ")";
+		return "(" + field + ')';
 	}
 }

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

@@ -62,6 +62,6 @@ public final class InsnWrapArg extends InsnArg {
 
 	@Override
 	public String toString() {
-		return "(wrap: " + type + "\n  " + wrappedInsn + ")";
+		return "(wrap: " + type + "\n  " + wrappedInsn + ')';
 	}
 }

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

@@ -69,10 +69,10 @@ public final class LiteralArg extends InsnArg {
 			if (getType().equals(ArgType.BOOLEAN) && (value.equals("true") || value.equals("false"))) {
 				return value;
 			}
-			return "(" + value + " " + type + ")";
+			return '(' + value + ' ' + type + ')';
 		} catch (JadxRuntimeException ex) {
 			// can't convert literal to string
-			return "(" + literal + " " + type + ")";
+			return "(" + literal + ' ' + type + ')';
 		}
 	}
 }

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

@@ -44,6 +44,6 @@ public final class NamedArg extends InsnArg implements Named {
 
 	@Override
 	public String toString() {
-		return "(" + name + " " + type + ")";
+		return '(' + name + ' ' + type + ')';
 	}
 }

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

@@ -169,17 +169,17 @@ public class RegisterArg extends InsnArg implements Named {
 		sb.append("(r");
 		sb.append(regNum);
 		if (sVar != null) {
-			sb.append("_").append(sVar.getVersion());
+			sb.append('_').append(sVar.getVersion());
 		}
 		if (getName() != null) {
-			sb.append(" '").append(getName()).append("'");
+			sb.append(" '").append(getName()).append('\'');
 		}
-		sb.append(" ");
+		sb.append(' ');
 		sb.append(type);
 		if (!isAttrStorageEmpty()) {
 			sb.append(' ').append(getAttributesString());
 		}
-		sb.append(")");
+		sb.append(')');
 		return sb.toString();
 	}
 }

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

@@ -206,6 +206,6 @@ public class SSAVar extends AttrNode {
 
 	@Override
 	public String toString() {
-		return "r" + regNum + "_" + version;
+		return "r" + regNum + '_' + version;
 	}
 }

jadx-core/src/main/java/jadx/core/dex/instructions/mods/ConstructorInsn.java

@@ -107,6 +107,6 @@ public class ConstructorInsn extends InsnNode implements CallMthInterface {
 
 	@Override
 	public String toString() {
-		return super.toString() + " " + callMth + " " + callType;
+		return super.toString() + ' ' + callMth + ' ' + callType;
 	}
 }

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

@@ -192,6 +192,6 @@ public class BlockNode extends AttrNode implements IBlock {
 
 	@Override
 	public String toString() {
-		return "B:" + id + ":" + InsnUtils.formatOffset(startOffset);
+		return "B:" + id + ':' + InsnUtils.formatOffset(startOffset);
 	}
 }

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

@@ -668,7 +668,7 @@ public class MethodNode extends LineAttrNode implements ILoadable, ICodeNode {
 	@Override
 	public String toString() {
 		return parentClass + "." + mthInfo.getName()
-				+ "(" + Utils.listToString(mthInfo.getArgumentsTypes()) + "):"
+				+ '(' + Utils.listToString(mthInfo.getArgumentsTypes()) + "):"
 				+ retType;
 	}
 }

jadx-core/src/main/java/jadx/core/dex/nodes/parser/LocalVar.java

@@ -119,8 +119,8 @@ final class LocalVar {
 
 	@Override
 	public String toString() {
-		return super.toString() + " " + (isEnd
-				? "end: " + InsnUtils.formatOffset(startAddr) + "-" + InsnUtils.formatOffset(endAddr)
+		return super.toString() + ' ' + (isEnd
+				? "end: " + InsnUtils.formatOffset(startAddr) + '-' + InsnUtils.formatOffset(endAddr)
 				: "active: " + InsnUtils.formatOffset(startAddr));
 	}
 }

jadx-core/src/main/java/jadx/core/dex/nodes/parser/SignatureParser.java

@@ -169,7 +169,7 @@ public class SignatureParser {
 			// generic type start ('<')
 			String obj = slice();
 			if (!incompleteType) {
-				obj += ";";
+				obj += ';';
 			}
 			ArgType[] genArr = consumeGenericArgs();
 			consume('>');

jadx-core/src/main/java/jadx/core/dex/regions/Region.java

@@ -53,6 +53,6 @@ public final class Region extends AbstractRegion {
 
 	@Override
 	public String toString() {
-		return "R" + baseString();
+		return 'R' + baseString();
 	}
 }

jadx-core/src/main/java/jadx/core/dex/regions/conditions/Compare.java

@@ -44,6 +44,6 @@ public final class Compare {
 
 	@Override
 	public String toString() {
-		return getA() + " " + getOp().getSymbol() + " " + getB();
+		return getA() + " " + getOp().getSymbol() + ' ' + getB();
 	}
 }

jadx-core/src/main/java/jadx/core/dex/regions/conditions/IfCondition.java

@@ -224,7 +224,7 @@ public final class IfCondition {
 			case TERNARY:
 				return first() + " ? " + second() + " : " + third();
 			case NOT:
-				return "!(" + first() + ")";
+				return "!(" + first() + ')';
 			case AND:
 			case OR:
 				String op = mode == Mode.OR ? " || " : " && ";

jadx-core/src/main/java/jadx/core/dex/regions/conditions/IfRegion.java

@@ -130,6 +130,6 @@ public final class IfRegion extends AbstractRegion implements IBranchRegion {
 
 	@Override
 	public String toString() {
-		return "IF " + header + " then (" + thenRegion + ") else (" + elseRegion + ")";
+		return "IF " + header + " then (" + thenRegion + ") else (" + elseRegion + ')';
 	}
 }

jadx-core/src/main/java/jadx/core/dex/trycatch/ExcHandlerAttr.java

@@ -30,6 +30,6 @@ public class ExcHandlerAttr implements IAttribute {
 	public String toString() {
 		return "ExcHandler: " + (handler.isFinally()
 				? " FINALLY"
-				: handler.catchTypeStr() + " " + handler.getArg());
+				: handler.catchTypeStr() + ' ' + handler.getArg());
 	}
 }

jadx-core/src/main/java/jadx/core/dex/visitors/CodeShrinker.java

@@ -162,8 +162,8 @@ public class CodeShrinker extends AbstractVisitor {
 		@Override
 		public String toString() {
 			return "ArgsInfo: |" + inlineBorder
-					+ " ->" + (inlinedInsn == null ? "-" : inlinedInsn.pos)
-					+ " " + args + " : " + insn;
+					+ " ->" + (inlinedInsn == null ? '-' : inlinedInsn.pos)
+					+ ' ' + args + " : " + insn;
 		}
 	}
 

jadx-core/src/main/java/jadx/core/dex/visitors/DotGraphVisitor.java

@@ -241,9 +241,9 @@ public class DotGraphVisitor extends AbstractVisitor {
 			if (c instanceof BlockNode) {
 				name = "Node_" + ((BlockNode) c).getId();
 			} else if (c instanceof IBlock) {
-				name = "Node_" + c.getClass().getSimpleName() + "_" + c.hashCode();
+				name = "Node_" + c.getClass().getSimpleName() + '_' + c.hashCode();
 			} else {
-				name = "cluster_" + c.getClass().getSimpleName() + "_" + c.hashCode();
+				name = "cluster_" + c.getClass().getSimpleName() + '_' + c.hashCode();
 			}
 			return name;
 		}

jadx-core/src/main/java/jadx/core/dex/visitors/ModVisitor.java

@@ -473,7 +473,7 @@ public class ModVisitor extends AbstractVisitor {
 		for (RegisterArg arg : mth.getArguments(false)) {
 			String name = arg.getName();
 			if (name != null && NameMapper.isReserved(name)) {
-				name = name + "_";
+				name = name + '_';
 				arg.getSVar().setName(name);
 			}
 		}

jadx-core/src/main/java/jadx/core/dex/visitors/RenameVisitor.java

@@ -79,7 +79,7 @@ public class RenameVisitor extends AbstractVisitor {
 		}
 		if (alias.getPackage().isEmpty()) {
 			String fullName = alias.makeFullClsName(alias.getShortName(), true);
-			String newFullName = Consts.DEFAULT_PACKAGE_NAME + "." + fullName;
+			String newFullName = Consts.DEFAULT_PACKAGE_NAME + '.' + fullName;
 			classInfo.rename(cls.root(), newFullName);
 		}
 	}

jadx-core/src/main/java/jadx/core/dex/visitors/blocksmaker/helpers/BlocksPair.java

@@ -38,6 +38,6 @@ public final class BlocksPair {
 
 	@Override
 	public String toString() {
-		return "(" + first + ", " + second + ")";
+		return "(" + first + ", " + second + ')';
 	}
 }

jadx-core/src/main/java/jadx/core/dex/visitors/blocksmaker/helpers/BlocksRemoveInfo.java

@@ -116,7 +116,7 @@ public final class BlocksRemoveInfo {
 				+ ", processed: " + processed
 				+ ", outs: " + outs
 				+ ", regMap: " + regMap
-				+ ", split: " + startSplitIndex + "-" + endSplitIndex
-				+ "}";
+				+ ", split: " + startSplitIndex + '-' + endSplitIndex
+				+ '}';
 	}
 }

jadx-core/src/main/java/jadx/core/dex/visitors/regions/ProcessVariables.java

@@ -58,7 +58,7 @@ public class ProcessVariables extends AbstractVisitor {
 
 		@Override
 		public String toString() {
-			return "r" + regNum + ":" + type;
+			return "r" + regNum + ':' + type;
 		}
 	}
 

jadx-core/src/main/java/jadx/core/dex/visitors/regions/RegionMaker.java

@@ -76,7 +76,7 @@ public class RegionMaker {
 
 		int startBlockId = startBlock.getId();
 		if (processedBlocks.get(startBlockId)) {
-			mth.addWarn("Removed duplicated region for block: " + startBlock + " " + startBlock.getAttributesString());
+			mth.addWarn("Removed duplicated region for block: " + startBlock + ' ' + startBlock.getAttributesString());
 			return r;
 		}
 		processedBlocks.set(startBlockId);

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

@@ -57,7 +57,7 @@ public class InsnUtils {
 			return "";
 		}
 		if (index instanceof String) {
-			return "\"" + index + "\"";
+			return "\"" + index + '"';
 		}
 		return index.toString();
 	}

jadx-core/src/main/java/jadx/core/utils/android/AndroidResourcesUtils.java

@@ -133,7 +133,7 @@ public class AndroidResourcesUtils {
 
 	@NotNull
 	private static ClassNode addClassForResType(ClassNode resCls, boolean rClsExists, String typeName) {
-		ClassNode newTypeCls = new ClassNode(resCls.dex(), resCls.getFullName() + "$" + typeName,
+		ClassNode newTypeCls = new ClassNode(resCls.dex(), resCls.getFullName() + '$' + typeName,
 				AccessFlags.ACC_PUBLIC | AccessFlags.ACC_STATIC | AccessFlags.ACC_FINAL);
 		resCls.addInnerClass(newTypeCls);
 		if (rClsExists) {

jadx-core/src/main/java/jadx/core/utils/files/DexFile.java

@@ -27,6 +27,6 @@ public class DexFile {
 
 	@Override
 	public String toString() {
-		return inputFile + (name.isEmpty() ? "" : ":" + name);
+		return inputFile + (name.isEmpty() ? "" : ':' + name);
 	}
 }

jadx-core/src/main/java/jadx/core/utils/files/FileUtils.java

@@ -67,7 +67,7 @@ public class FileUtils {
 	public static File createTempFile(String suffix) {
 		File temp;
 		try {
-			temp = File.createTempFile("jadx-tmp-", System.nanoTime() + "-" + suffix);
+			temp = File.createTempFile("jadx-tmp-", System.nanoTime() + '-' + suffix);
 			temp.deleteOnExit();
 		} catch (IOException e) {
 			throw new JadxRuntimeException("Failed to create temp file with suffix: " + suffix);
@@ -77,7 +77,7 @@ public class FileUtils {
 
 	public static File createTempDir(String suffix) {
 		try {
-			Path path = Files.createTempDirectory("jadx-tmp-" + System.nanoTime() + "-" + suffix);
+			Path path = Files.createTempDirectory("jadx-tmp-" + System.nanoTime() + '-' + suffix);
 			path.toFile().deleteOnExit();
 			return path.toFile();
 		} catch (IOException e) {

jadx-core/src/main/java/jadx/core/xmlgen/BinaryXMLParser.java

@@ -209,7 +209,7 @@ public class BinaryXMLParser extends CommonBinaryParser {
 		String str = getString(strIndex);
 		if (!isLastEnd) {
 			isLastEnd = true;
-			writer.add(">");
+			writer.add('>');
 		}
 		writer.attachSourceLine(lineNumber);
 		String escapedStr = StringUtils.escapeXML(str);
@@ -235,13 +235,13 @@ public class BinaryXMLParser extends CommonBinaryParser {
 		int startNS = is.readInt32();
 		int startNSName = is.readInt32(); // actually is elementName...
 		if (!isLastEnd && !"ERROR".equals(currentTag)) {
-			writer.add(">");
+			writer.add('>');
 		}
 		isOneLine = true;
 		isLastEnd = false;
 		currentTag = deobfClassName(getString(startNSName));
 		currentTag = getValidTagAttributeName(currentTag);
-		writer.startLine("<").add(currentTag);
+		writer.startLine('<').add(currentTag);
 		writer.attachSourceLine(elementBegLineNumber);
 		int attributeStart = is.readInt16();
 		if (attributeStart != 0x14) {
@@ -263,7 +263,7 @@ public class BinaryXMLParser extends CommonBinaryParser {
 					writer.add(':');
 					writer.add(nsValue);
 				}
-				writer.add("=\"").add(StringUtils.escapeXML(entry.getKey())).add("\"");
+				writer.add("=\"").add(StringUtils.escapeXML(entry.getKey())).add('"');
 			}
 		}
 		boolean attrNewLine = attributeCount != 1 && ATTR_NEW_LINE;
@@ -373,13 +373,13 @@ public class BinaryXMLParser extends CommonBinaryParser {
 			// reference custom processing
 			String name = styleMap.get(attrValData);
 			if (name != null) {
-				writer.add("@style/").add(name.replaceAll("_", "."));
+				writer.add("@style/").add(name.replace('_', '.'));
 			} else {
 				String resName = resNames.get(attrValData);
 				if (resName != null) {
-					writer.add("@");
+					writer.add('@');
 					if (resName.startsWith("id/")) {
-						writer.add("+");
+						writer.add('+');
 					}
 					writer.add(resName);
 				} else {
@@ -424,7 +424,7 @@ public class BinaryXMLParser extends CommonBinaryParser {
 //			if (elementNS != -1) {
 //				writer.add(getString(elementNS)).add(':');
 //			}
-			writer.add(elemName).add(">");
+			writer.add(elemName).add('>');
 		}
 		isLastEnd = true;
 		if (writer.getIndent() != 0) {
@@ -470,7 +470,7 @@ public class BinaryXMLParser extends CommonBinaryParser {
 	private boolean isDeobfCandidateAttr(String shortNsName, String attrName) {
 		String fullName;
 		if (shortNsName != null) {
-			fullName = shortNsName + ":" + attrName;
+			fullName = shortNsName + ':' + attrName;
 		} else {
 			return false;
 		}

jadx-core/src/main/java/jadx/core/xmlgen/ManifestAttributes.java

@@ -43,7 +43,7 @@ public class ManifestAttributes {
 
 		@Override
 		public String toString() {
-			return "[" + type + ", " + values + "]";
+			return "[" + type + ", " + values + ']';
 		}
 	}
 
@@ -173,7 +173,7 @@ public class ManifestAttributes {
 			StringBuilder sb = new StringBuilder();
 			for (Map.Entry<Long, String> entry : attr.getValues().entrySet()) {
 				if (value == entry.getKey()) {
-					sb = new StringBuilder(entry.getValue() + "|");
+					sb = new StringBuilder(entry.getValue() + '|');
 					break;
 				} else if ((value & entry.getKey()) == entry.getKey()) {
 					sb.append(entry.getValue()).append('|');

jadx-core/src/main/java/jadx/core/xmlgen/ResContainer.java

@@ -49,7 +49,7 @@ public class ResContainer implements Comparable<ResContainer> {
 	}
 
 	public String getFileName() {
-		return name.replace("/", File.separator);
+		return name.replace('/', File.separatorChar);
 	}
 
 	public List<ResContainer> getSubFiles() {
@@ -96,6 +96,6 @@ public class ResContainer implements Comparable<ResContainer> {
 
 	@Override
 	public String toString() {
-		return "Res{" + name + ", type=" + dataType + ", subFiles=" + subFiles + "}";
+		return "Res{" + name + ", type=" + dataType + ", subFiles=" + subFiles + '}';
 	}
 }

jadx-core/src/main/java/jadx/core/xmlgen/ResTableParser.java

@@ -81,7 +81,7 @@ public class ResTableParser extends CommonBinaryParser {
 
 		Set<String> addedValues = new HashSet<>();
 		for (ResourceEntry ri : resStorage.getResources()) {
-			if (addedValues.add(ri.getTypeName() + "." + ri.getKeyName())) {
+			if (addedValues.add(ri.getTypeName() + '.' + ri.getKeyName())) {
 				String format = String.format("<public type=\"%s\" name=\"%s\" id=\"%s\" />",
 						ri.getTypeName(), ri.getKeyName(), ri.getId());
 				writer.startLine(format);

jadx-core/src/main/java/jadx/core/xmlgen/ResXmlGen.java

@@ -180,9 +180,9 @@ public class ResXmlGen {
 		cw.add('<').add(itemTag);
 		if (attrName != null && attrValue != null) {
 			if (typeName.equals("attr")) {
-				cw.add(' ').add("name=\"").add(attrName.replace("id.", "")).add("\" value=\"").add(attrValue).add("\"");
+				cw.add(' ').add("name=\"").add(attrName.replace("id.", "")).add("\" value=\"").add(attrValue).add('"');
 			} else if (typeName.equals("style")) {
-				cw.add(' ').add("name=\"").add(attrName.replace("attr.", "")).add("\"");
+				cw.add(' ').add("name=\"").add(attrName.replace("attr.", "")).add('"');
 			} else {
 				cw.add(' ').add(attrName).add("=\"").add(attrValue).add('"');
 			}

jadx-core/src/main/java/jadx/core/xmlgen/ResourceStorage.java

@@ -47,7 +47,7 @@ public class ResourceStorage {
 	public Map<Integer, String> getResourcesNames() {
 		Map<Integer, String> map = new HashMap<>();
 		for (ResourceEntry entry : list) {
-			map.put(entry.getId(), entry.getTypeName() + "/" + entry.getKeyName());
+			map.put(entry.getId(), entry.getTypeName() + '/' + entry.getKeyName());
 		}
 		return map;
 	}

jadx-core/src/main/java/jadx/core/xmlgen/entry/EntryConfig.java

@@ -450,7 +450,7 @@ public class EntryConfig {
         // denies values-xxx, anything else
         if (localeVariant == null && localeScript == null && (region[0] != '\00' || language[0] != '\00') &&
                 region.length != 3) {
-            sb.append("-").append(language);
+            sb.append('-').append(language);
             if (region[0] != '\00') {
                 sb.append("-r").append(region);
             }
@@ -463,13 +463,13 @@ public class EntryConfig {
                 sb.append(language);
             }
             if (localeScript != null && localeScript.length == 4) {
-                sb.append("+").append(localeScript);
+                sb.append('+').append(localeScript);
             }
             if ((region.length == 2 || region.length == 3) && region[0] != '\00') {
-                sb.append("+").append(region);
+                sb.append('+').append(region);
             }
             if (localeVariant != null && localeVariant.length >= 5) {
-                sb.append("+").append(toUpper(localeVariant));
+                sb.append('+').append(toUpper(localeVariant));
             }
         }
         return sb.toString();

jadx-core/src/main/java/jadx/core/xmlgen/entry/ResourceEntry.java

@@ -75,6 +75,6 @@ public final class ResourceEntry {
 
 	@Override
 	public String toString() {
-		return "  0x" + Integer.toHexString(id) + " (" + id + ")" + config + " = " + typeName + "." + keyName;
+		return "  0x" + Integer.toHexString(id) + " (" + id + ')' + config + " = " + typeName + '.' + keyName;
 	}
 }

jadx-core/src/main/java/jadx/core/xmlgen/entry/ValuesParser.java

@@ -60,7 +60,7 @@ public class ValuesParser extends ParserConstants {
 			if (nameStr == null) {
 				strList.add(valueStr);
 			} else {
-				strList.add(nameStr + "=" + valueStr);
+				strList.add(nameStr + '=' + valueStr);
 			}
 		}
 		return strList.toString();
@@ -110,7 +110,7 @@ public class ValuesParser extends ParserConstants {
 					}
 					return "?unknown_ref: " + Integer.toHexString(data);
 				}
-				return "@" + ri;
+				return '@' + ri;
 			}
 
 			case TYPE_ATTRIBUTE: {
@@ -122,7 +122,7 @@ public class ValuesParser extends ParserConstants {
 					}
 					return "?unknown_attr_ref: " + Integer.toHexString(data);
 				}
-				return "?" + ri;
+				return '?' + ri;
 			}
 
 			case TYPE_DIMENSION:
@@ -132,7 +132,7 @@ public class ValuesParser extends ParserConstants {
 
 			default:
 				LOG.warn("Unknown data type: 0x{} {}", Integer.toHexString(dataType), data);
-				return "  ?0x" + Integer.toHexString(dataType) + " " + data;
+				return "  ?0x" + Integer.toHexString(dataType) + ' ' + data;
 		}
 	}
 

jadx-gui/src/main/java/jadx/gui/settings/JadxSettingsWindow.java

@@ -211,7 +211,7 @@ public class JadxSettingsWindow extends JDialog {
 	private String getFontLabelStr() {
 		Font font = settings.getFont();
 		String fontStyleName = Utils.getFontStyleName(font.getStyle());
-		return NLS.str("preferences.font") + ": " + font.getFontName() + " " + fontStyleName + " " + font.getSize();
+		return NLS.str("preferences.font") + ": " + font.getFontName() + ' ' + fontStyleName + ' ' + font.getSize();
 	}
 
 	private SettingsGroup makeDecompilationGroup() {

jadx-gui/src/main/java/jadx/gui/treemodel/JMethod.java

@@ -94,7 +94,7 @@ public class JMethod extends JNode {
 
 	@Override
 	public String makeLongString() {
-		String name = mth.getDeclaringClass().getFullName() + "." + makeBaseString();
+		String name = mth.getDeclaringClass().getFullName() + '.' + makeBaseString();
 		return Utils.typeFormat(name, getReturnType());
 	}
 

jadx-gui/src/main/java/jadx/gui/treemodel/JSources.java

@@ -66,7 +66,7 @@ public class JSources extends JNode {
 					pkg.getInnerPackages().clear();
 					pkg.getInnerPackages().addAll(innerPkg.getInnerPackages());
 					pkg.getClasses().addAll(innerPkg.getClasses());
-					pkg.setName(pkg.getName() + "." + innerPkg.getName());
+					pkg.setName(pkg.getName() + '.' + innerPkg.getName());
 
 					innerPkg.getInnerPackages().clear();
 					innerPkg.getClasses().clear();

jadx-gui/src/main/java/jadx/gui/ui/codearea/SearchBar.java

@@ -44,7 +44,7 @@ class SearchBar extends JToolBar {
 	public SearchBar(RSyntaxTextArea textArea) {
 		rTextArea = textArea;
 
-		JLabel findLabel = new JLabel(NLS.str("search.find") + ":");
+		JLabel findLabel = new JLabel(NLS.str("search.find") + ':');
 		add(findLabel);
 
 		searchField = new JTextField(30);