core: use own immutable list

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

@@ -15,6 +15,8 @@ import jadx.core.utils.BlockUtils;
 import jadx.core.utils.EmptyBitSet;
 import jadx.core.utils.InsnUtils;
 
+import static jadx.core.utils.Utils.lockList;
+
 public class BlockNode extends AttrNode implements IBlock {
 
 	private int id;
@@ -70,13 +72,6 @@ public class BlockNode extends AttrNode implements IBlock {
 		dominatesOn = lockList(dominatesOn);
 	}
 
-	List<BlockNode> lockList(List<BlockNode> list) {
-		if (list.isEmpty()) {
-			return Collections.emptyList();
-		}
-		return Collections.unmodifiableList(list);
-	}
-
 	/**
 	 * Return all successor which are not exception handler or followed by loop back edge
 	 */

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

@@ -43,6 +43,8 @@ import jadx.core.utils.Utils;
 import jadx.core.utils.exceptions.DecodeException;
 import jadx.core.utils.exceptions.JadxRuntimeException;
 
+import static jadx.core.utils.Utils.lockList;
+
 public class MethodNode extends LineAttrNode implements ILoadable, IDexNode {
 	private static final Logger LOG = LoggerFactory.getLogger(MethodNode.class);
 
@@ -154,10 +156,10 @@ public class MethodNode extends LineAttrNode implements ILoadable, IDexNode {
 		blocks = null;
 		enterBlock = null;
 		exitBlocks = null;
-		exceptionHandlers.clear();
+		exceptionHandlers = Collections.emptyList();
 		sVars.clear();
 		region = null;
-		loops.clear();
+		loops = Collections.emptyList();
 	}
 
 	private boolean parseSignature() {
@@ -407,21 +409,10 @@ public class MethodNode extends LineAttrNode implements ILoadable, IDexNode {
 	}
 
 	public void finishBasicBlocks() {
-		trimList(blocks);
-		trimList(exitBlocks);
-
-		blocks = Collections.unmodifiableList(blocks);
-		exitBlocks = Collections.unmodifiableList(exitBlocks);
-
-		for (BlockNode block : blocks) {
-			block.lock();
-		}
-	}
-
-	private void trimList(List<BlockNode> blocks) {
-		if (blocks instanceof ArrayList) {
-			((ArrayList<BlockNode>)blocks).trimToSize();
-		}
+		blocks = lockList(blocks);
+		exitBlocks = lockList(exitBlocks);
+		loops = lockList(loops);
+		blocks.forEach(BlockNode::lock);
 	}
 
 	public List<BlockNode> getBasicBlocks() {

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

@@ -0,0 +1,220 @@
+package jadx.core.utils;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+import java.util.Objects;
+import java.util.RandomAccess;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+import java.util.function.UnaryOperator;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Simple immutable list implementation
+ * Warning: some methods not implemented!
+ */
+public final class ImmutableList<E> implements List<E>, RandomAccess {
+	private final E[] arr;
+
+	@SuppressWarnings("unchecked")
+	public ImmutableList(Object[] arr) {
+		this.arr = (E[]) Objects.requireNonNull(arr);
+	}
+
+	@Override
+	public int size() {
+		return arr.length;
+	}
+
+	@Override
+	public boolean isEmpty() {
+		return arr.length == 0;
+	}
+
+	@Override
+	public E get(int index) {
+		return arr[index];
+	}
+
+	@Override
+	public int indexOf(Object o) {
+		int len = arr.length;
+		for (int i = 0; i < len; i++) {
+			E e = arr[i];
+			if (Objects.equals(e, o)) {
+				return i;
+			}
+		}
+		return -1;
+	}
+
+	@Override
+	public int lastIndexOf(Object o) {
+		for (int i = arr.length - 1; i > 0; i--) {
+			E e = arr[i];
+			if (Objects.equals(e, o)) {
+				return i;
+			}
+		}
+		return -1;
+	}
+
+	@Override
+	public boolean contains(Object o) {
+		return indexOf(o) != -1;
+	}
+
+	@Override
+	public boolean containsAll(@NotNull Collection<?> c) {
+		throw new UnsupportedOperationException();
+	}
+
+	@NotNull
+	@Override
+	public Iterator<E> iterator() {
+		return new Iterator<E>() {
+			private int index = 0;
+			private int len = arr.length;
+
+			@Override
+			public boolean hasNext() {
+				return index < len;
+			}
+
+			@Override
+			public E next() {
+				return arr[index++];
+			}
+		};
+	}
+
+	@Override
+	public void forEach(Consumer<? super E> action) {
+		for (E e : arr) {
+			action.accept(e);
+		}
+	}
+
+	@NotNull
+	@Override
+	public Object[] toArray() {
+		return arr;
+	}
+
+	@NotNull
+	@Override
+	@SuppressWarnings("unchecked")
+	public <T> T[] toArray(@NotNull T[] a) {
+		return (T[]) arr;
+	}
+
+	@Override
+	public boolean add(E e) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean remove(Object o) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean addAll(@NotNull Collection<? extends E> c) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean addAll(int index, @NotNull Collection<? extends E> c) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean removeAll(@NotNull Collection<?> c) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean retainAll(@NotNull Collection<?> c) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void replaceAll(UnaryOperator<E> operator) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void sort(Comparator<? super E> c) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean removeIf(Predicate<? super E> filter) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void clear() {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public E set(int index, E element) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void add(int index, E element) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public E remove(int index) {
+		throw new UnsupportedOperationException();
+	}
+
+	@NotNull
+	@Override
+	public ListIterator<E> listIterator() {
+		throw new UnsupportedOperationException();
+	}
+
+	@NotNull
+	@Override
+	public ListIterator<E> listIterator(int index) {
+		throw new UnsupportedOperationException();
+	}
+
+	@NotNull
+	@Override
+	public List<E> subList(int fromIndex, int toIndex) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) {
+			return true;
+		}
+		if (o == null || getClass() != o.getClass()) {
+			return false;
+		}
+		ImmutableList<?> that = (ImmutableList<?>) o;
+		return Arrays.equals(arr, that.arr);
+	}
+
+	@Override
+	public int hashCode() {
+		return Arrays.hashCode(arr);
+	}
+
+	@Override
+	public String toString() {
+		return "ImmutableList{" + Arrays.toString(arr) + '}';
+	}
+}

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

@@ -3,7 +3,9 @@ package jadx.core.utils;
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Iterator;
+import java.util.List;
 import java.util.function.Function;
 
 import jadx.api.JadxDecompiler;
@@ -107,4 +109,15 @@ public class Utils {
 			th.setStackTrace(Arrays.copyOfRange(stackTrace, 0, cutIndex));
 		}
 	}
+
+	@SuppressWarnings("unchecked")
+	public static <T> List<T> lockList(List<T> list) {
+		if (list.isEmpty()) {
+			return Collections.emptyList();
+		}
+		if (list.size() == 1) {
+			return Collections.singletonList(list.get(0));
+		}
+		return new ImmutableList<>(list.toArray());
+	}
 }