Merge branch 'master' into type-inference-wip

# Conflicts:
#	jadx-core/src/main/java/jadx/core/codegen/NameGen.java
#	jadx-core/src/main/java/jadx/core/dex/attributes/AttributeStorage.java
#	jadx-core/src/main/java/jadx/core/dex/attributes/nodes/PhiListAttr.java
#	jadx-core/src/main/java/jadx/core/dex/instructions/IndexInsnNode.java
#	jadx-core/src/main/java/jadx/core/dex/instructions/InsnDecoder.java
#	jadx-core/src/main/java/jadx/core/dex/instructions/args/ArgType.java
#	jadx-core/src/main/java/jadx/core/dex/instructions/args/RegisterArg.java
#	jadx-core/src/main/java/jadx/core/dex/instructions/args/SSAVar.java
#	jadx-core/src/main/java/jadx/core/dex/regions/conditions/IfRegion.java
#	jadx-core/src/main/java/jadx/core/dex/visitors/ModVisitor.java
#	jadx-core/src/main/java/jadx/core/dex/visitors/blocksmaker/helpers/BlocksPair.java
#	jadx-core/src/main/java/jadx/core/dex/visitors/blocksmaker/helpers/BlocksRemoveInfo.java
#	jadx-core/src/main/java/jadx/core/dex/visitors/debuginfo/LocalVar.java
#	jadx-core/src/main/java/jadx/core/dex/visitors/regions/ProcessVariables.java
#	jadx-core/src/main/java/jadx/core/dex/visitors/shrink/CodeShrinkVisitor.java
#	jadx-core/src/main/java/jadx/core/xmlgen/entry/EntryConfig.java

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/core/codegen/InsnGen.java

@@ -499,12 +499,12 @@ public class InsnGen {
 
 			case PHI:
 				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

@@ -184,9 +184,9 @@ 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())

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

@@ -129,7 +129,7 @@ public class TypeGen {
 		}
 		String str = Long.toString(l);
 		if (Math.abs(l) >= Integer.MAX_VALUE) {
-			str += "L";
+			str += 'L';
 		}
 		return str;
 	}

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('>');
@@ -211,7 +211,7 @@ public class SignatureParser {
 				list.add(type);
 			}
 		} while (type != null && !lookAhead('>'));
-		return list.toArray(new ArgType[list.size()]);
+		return list.toArray(new ArgType[0]);
 	}
 
 	/**

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);

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) {

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() {

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

@@ -182,9 +182,9 @@ 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/test/java/jadx/api/JadxArgsValidatorOutDirsTest.java

@@ -44,8 +44,8 @@ public class JadxArgsValidatorOutDirsTest {
 		setOutDirs(null, null, null);
 		String inputFileBase = args.getInputFiles().get(0).getName().replace(".apk", "");
 		checkOutDirs(inputFileBase,
-				inputFileBase + "/" + JadxArgs.DEFAULT_SRC_DIR,
-				inputFileBase + "/" + JadxArgs.DEFAULT_RES_DIR);
+				inputFileBase + '/' + JadxArgs.DEFAULT_SRC_DIR,
+				inputFileBase + '/' + JadxArgs.DEFAULT_RES_DIR);
 	}
 
 	private void setOutDirs(String outDir, String srcDir, String resDir) {

jadx-core/src/test/java/jadx/core/dex/visitors/typeinference/TypeCompareTest.java

@@ -122,7 +122,7 @@ public class TypeCompareTest {
 
 	private void check(ArgType first, ArgType second, TypeCompareEnum expectedResult) {
 		TypeCompareEnum result = compare.compareTypes(first, second);
-		assertThat("Compare '" + first + "' vs '" + second + "'",
+		assertThat("Compare '" + first + "' vs '" + second + '\'',
 				result, is(expectedResult));
 	}
 }

jadx-core/src/test/java/jadx/tests/api/IntegrationTest.java

@@ -317,7 +317,7 @@ public abstract class IntegrationTest extends TestUtils {
 		File temp = createTempFile(".jar");
 		try (JarOutputStream jo = new JarOutputStream(new FileOutputStream(temp))) {
 			for (File file : list) {
-				addFileToJar(jo, file, path + "/" + file.getName());
+				addFileToJar(jo, file, path + '/' + file.getName());
 			}
 		}
 		return temp;
@@ -340,7 +340,7 @@ public abstract class IntegrationTest extends TestUtils {
 
 	private static File createTempDir(String prefix) throws IOException {
 		File baseDir = new File(System.getProperty("java.io.tmpdir"));
-		String baseName = prefix + "-" + System.nanoTime();
+		String baseName = prefix + '-' + System.nanoTime();
 		for (int counter = 1; counter < 1000; counter++) {
 			File tempDir = new File(baseDir, baseName + counter);
 			if (tempDir.mkdir()) {
@@ -360,7 +360,7 @@ public abstract class IntegrationTest extends TestUtils {
 				File directory = new File(pkgResource.toURI());
 				String[] files = directory.list();
 				for (String file : files) {
-					String fullName = pkgName + "." + file;
+					String fullName = pkgName + '.' + file;
 					if (fullName.startsWith(clsName)) {
 						list.add(new File(directory, file));
 					}

jadx-core/src/test/java/jadx/tests/api/SmaliTest.java

@@ -44,7 +44,7 @@ public abstract class SmaliTest extends IntegrationTest {
 	protected ClassNode getClassNodeFromSmaliFiles(String pkg, String testName, String clsName) {
 		File outDex = createTempFile(".dex");
 		compileSmali(outDex, collectSmaliFiles(pkg, testName));
-		return getClassNodeFromFile(outDex, pkg + "." + clsName);
+		return getClassNodeFromFile(outDex, pkg + '.' + clsName);
 	}
 
 	protected JadxDecompiler loadSmaliFile(String pkg, String smaliFileName) {

jadx-core/src/test/java/jadx/tests/functional/StringUtilsTest.java

@@ -32,7 +32,7 @@ class StringUtilsTest {
 	}
 
 	private void checkStringUnescape(String input, String result) {
-		assertThat(stringUtils.unescapeString(input), is("\"" + result + "\""));
+		assertThat(stringUtils.unescapeString(input), is('"' + result + '"'));
 	}
 
 	@Test
@@ -47,6 +47,6 @@ class StringUtilsTest {
 	}
 
 	private void checkCharUnescape(char input, String result) {
-		assertThat(stringUtils.unescapeChar(input), is("'" + result + "'"));
+		assertThat(stringUtils.unescapeChar(input), is('\'' + result + '\''));
 	}
 }

jadx-core/src/test/java/jadx/tests/integration/TestStringBuilderElimination2.java

@@ -18,7 +18,7 @@ public class TestStringBuilderElimination2 extends IntegrationTest {
 
 	public static class TestCls1 {
 		public String test() {
-			return new StringBuilder("[init]").append("a1").append('c').append(2).append(0l).append(1.0f).
+			return new StringBuilder("[init]").append("a1").append('c').append(2).append(0L).append(1.0f).
 					append(2.0d).append(true).toString();
 		}
 	}

jadx-core/src/test/java/jadx/tests/integration/annotations/AnnotationsRenaming.java

+package jadx.tests.integration.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.NotYetImplemented;
+import jadx.core.dex.nodes.ClassNode;
+import jadx.tests.api.IntegrationTest;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+public class AnnotationsRenaming extends IntegrationTest {
+
+	public static class TestCls {
+
+		@Target({ElementType.METHOD})
+		@Retention(RetentionPolicy.RUNTIME)
+		public static @interface A {
+			int x();
+		}
+
+		@A(x = 5)
+		void test() {
+		}
+
+	}
+
+	@Test
+	@NotYetImplemented
+	public void test504() {
+		enableDeobfuscation();
+		ClassNode cls = getClassNode(TestCls.class);
+		String code = cls.getCode().toString();
+
+		assertThat(code, containsString("public static @interface "));
+		assertThat(code, not(containsString("(x = 5)")));
+	}
+}

jadx-core/src/test/java/jadx/tests/integration/enums/TestEnums.java

@@ -46,10 +46,10 @@ public class TestEnums extends IntegrationTest {
 		assertThat(code, containsLines(1, "public enum EmptyEnum {", "}"));
 		assertThat(code, containsLines(1,
 				"public enum EmptyEnum2 {",
-				indent(1) + ";",
+				indent(1) + ';',
 				"",
 				indent(1) + "public static void mth() {",
-				indent(1) + "}",
+				indent(1) + '}',
 				"}"));
 
 		assertThat(code, containsLines(1, "public enum Direction {",
@@ -64,7 +64,7 @@ public class TestEnums extends IntegrationTest {
 				"",
 				indent(1) + "public String test() {",
 				indent(2) + "return \"\";",
-				indent(1) + "}",
+				indent(1) + '}',
 				"}"));
 	}
 }

jadx-core/src/test/java/jadx/tests/integration/enums/TestEnums2.java

@@ -38,12 +38,12 @@ public class TestEnums2 extends IntegrationTest {
 				indent(1) + "PLUS {",
 				indent(2) + "public int apply(int x, int y) {",
 				indent(3) + "return x + y;",
-				indent(2) + "}",
+				indent(2) + '}',
 				indent(1) + "},",
 				indent(1) + "MINUS {",
 				indent(2) + "public int apply(int x, int y) {",
 				indent(3) + "return x - y;",
-				indent(2) + "}",
+				indent(2) + '}',
 				indent(1) + "};",
 				"",
 				indent(1) + "public abstract int apply(int i, int i2);",

jadx-core/src/test/java/jadx/tests/integration/enums/TestEnums3.java

@@ -7,7 +7,7 @@ import jadx.tests.api.IntegrationTest;
 
 import static jadx.tests.api.utils.JadxMatchers.containsOne;
 import static org.hamcrest.MatcherAssert.assertThat;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class TestEnums3 extends IntegrationTest {
 
@@ -30,9 +30,9 @@ public class TestEnums3 extends IntegrationTest {
 		}
 
 		public void check() {
-			assertTrue(Numbers.ONE.getNum() == 1);
-			assertTrue(Numbers.THREE.getNum() == 3);
-			assertTrue(Numbers.FOUR.getNum() == 4);
+			assertEquals(1, Numbers.ONE.getNum());
+			assertEquals(3, Numbers.THREE.getNum());
+			assertEquals(4, Numbers.FOUR.getNum());
 		}
 	}
 

jadx-core/src/test/java/jadx/tests/integration/enums/TestEnumsInterface.java

@@ -40,13 +40,13 @@ public class TestEnumsInterface extends IntegrationTest {
 				indent(1) + "PLUS {",
 				indent(2) + "public int apply(int x, int y) {",
 				indent(3) + "return x + y;",
-				indent(2) + "}",
+				indent(2) + '}',
 				indent(1) + "},",
 				indent(1) + "MINUS {",
 				indent(2) + "public int apply(int x, int y) {",
 				indent(3) + "return x - y;",
-				indent(2) + "}",
-				indent(1) + "}",
+				indent(2) + '}',
+				indent(1) + '}',
 				"}"
 		));
 	}

jadx-core/src/test/java/jadx/tests/integration/inner/TestAnonymousClass4.java

@@ -37,9 +37,9 @@ public class TestAnonymousClass4 extends IntegrationTest {
 		String code = cls.getCode().toString();
 
 		assertThat(code, containsOne(indent(3) + "new Thread() {"));
-		assertThat(code, containsOne(indent(4) + "{"));
+		assertThat(code, containsOne(indent(4) + '{'));
 		assertThat(code, containsOne("f = 1;"));
-		assertThat(code, countString(2, indent(4) + "}"));
+		assertThat(code, countString(2, indent(4) + '}'));
 		assertThat(code, containsOne(indent(4) + "public void run() {"));
 		assertThat(code, containsOne("d = 7.5"));
 		assertThat(code, containsOne(indent(3) + "}.start();"));

jadx-core/src/test/java/jadx/tests/integration/loops/TestArrayForEach2.java

@@ -35,7 +35,7 @@ public class TestArrayForEach2 extends IntegrationTest {
 				indent(1) + "String t = s.trim();",
 				indent(1) + "if (t.length() > 0) {",
 				indent(2) + "System.out.println(t);",
-				indent(1) + "}",
+				indent(1) + '}',
 				"}"
 		));
 	}

jadx-core/src/test/java/jadx/tests/integration/others/TestIssue13a.java

@@ -41,18 +41,18 @@ public class TestIssue13a extends IntegrationTest {
 						Field f = c.getField("CREATOR");
 						creator = (Parcelable.Creator) f.get(null);
 					} catch (IllegalAccessException e) {
-						Log.e(TAG, "1" + name + ", e: " + e);
-						throw new RuntimeException("2" + name);
+						Log.e(TAG, '1' + name + ", e: " + e);
+						throw new RuntimeException('2' + name);
 					} catch (ClassNotFoundException e) {
-						Log.e(TAG, "3" + name + ", e: " + e);
-						throw new RuntimeException("4" + name);
+						Log.e(TAG, '3' + name + ", e: " + e);
+						throw new RuntimeException('4' + name);
 					} catch (ClassCastException e) {
-						throw new RuntimeException("5" + name);
+						throw new RuntimeException('5' + name);
 					} catch (NoSuchFieldException e) {
-						throw new RuntimeException("6" + name);
+						throw new RuntimeException('6' + name);
 					}
 					if (creator == null) {
-						throw new RuntimeException("7" + name);
+						throw new RuntimeException('7' + name);
 					}
 					map.put(name, creator);
 				}
@@ -95,7 +95,7 @@ public class TestIssue13a extends IntegrationTest {
 		String code = cls.getCode().toString();
 
 		for (int i = 1; i <= 7; i++) {
-			assertThat(code, containsOne("\"" + i + "\""));
+			assertThat(code, containsOne("'" + i + '\''));
 		}
 
 		// TODO: add additional checks

jadx-core/src/test/java/jadx/tests/integration/synchronize/TestSynchronized.java

@@ -38,7 +38,7 @@ public class TestSynchronized extends IntegrationTest {
 		assertThat(code, containsOne("return this.f"));
 		assertThat(code, containsOne("synchronized (this.o) {"));
 
-		assertThat(code, not(containsString(indent(3) + ";")));
+		assertThat(code, not(containsString(indent(3) + ';')));
 		assertThat(code, not(containsString("try {")));
 		assertThat(code, not(containsString("} catch (Throwable th) {")));
 		assertThat(code, not(containsString("throw th;")));

jadx-core/src/test/java/jadx/tests/integration/trycatch/TestTryCatch7.java

@@ -43,8 +43,8 @@ public class TestTryCatch7 extends IntegrationTest {
 	private void check(String code, String excVarName, String catchExcVarName) {
 		assertThat(code, containsOne("Exception " + excVarName + " = new Exception();"));
 		assertThat(code, containsOne("} catch (Exception " + catchExcVarName + ") {"));
-		assertThat(code, containsOne(excVarName + " = " + catchExcVarName + ";"));
+		assertThat(code, containsOne(excVarName + " = " + catchExcVarName + ';'));
 		assertThat(code, containsOne(excVarName + ".printStackTrace();"));
-		assertThat(code, containsOne("return " + excVarName + ";"));
+		assertThat(code, containsOne("return " + excVarName + ';'));
 	}
 }

jadx-core/src/test/java/jadx/tests/integration/trycatch/TestTryCatchFinally6.java

@@ -44,7 +44,7 @@ public class TestTryCatchFinally6 extends IntegrationTest {
 				"} finally {",
 				indent(1) + "if (is != null) {",
 				indent(2) + "is.close();",
-				indent(1) + "}",
+				indent(1) + '}',
 				"}"
 		));
 	}
@@ -63,7 +63,7 @@ public class TestTryCatchFinally6 extends IntegrationTest {
 				"} finally {",
 				indent() + "if (fileInputStream != null) {",
 				indent() + indent() + "fileInputStream.close();",
-				indent() + "}",
+				indent() + '}',
 				"}"
 		));
 	}

jadx-core/src/test/java/jadx/tests/integration/trycatch/TestTryCatchInIf.java

@@ -23,7 +23,7 @@ public class TestTryCatchInIf extends IntegrationTest {
 					} else {
 						key = Integer.parseInt(value);
 					}
-					return name + "=" + key;
+					return name + '=' + key;
 				} catch (NumberFormatException e) {
 					return "Failed to parse number";
 				}

jadx-core/src/test/java/jadx/tests/integration/variables/TestVariables4.java

@@ -37,7 +37,7 @@ public class TestVariables4 extends IntegrationTest {
 					msg = "not extends AbstractTest";
 				}
 				System.err.println(">> "
-						+ (pass ? "PASS" : "FAIL") + "\t"
+						+ (pass ? "PASS" : "FAIL") + '\t'
 						+ clsName
 						+ (msg == null ? "" : "\t - " + msg));
 				if (exc != null) {

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);

jadx-gui/src/main/java/jadx/gui/utils/CertificateManager.java

@@ -126,13 +126,13 @@ public class CertificateManager {
 		StringBuilder builder = new StringBuilder();
 		if (x509cert != null) {
 			builder.append(generateHeader());
-			builder.append("\n");
+			builder.append('\n');
 
 			builder.append(generatePublicKey());
-			builder.append("\n");
+			builder.append('\n');
 
 			builder.append(generateSignature());
-			builder.append("\n");
+			builder.append('\n');
 			builder.append(generateFingerprint());
 		}
 		return builder.toString();
@@ -150,7 +150,7 @@ public class CertificateManager {
 	}
 
 	static void append(StringBuilder str, String name, String value) {
-		str.append(name).append(": ").append(value).append("\n");
+		str.append(name).append(": ").append(value).append('\n');
 	}
 
 	public static String getThumbPrint(X509Certificate cert, String type)

jadx-samples/src/main/java/jadx/samples/RunTests.java

@@ -65,7 +65,7 @@ public class RunTests {
 				msg = "not extends AbstractTest";
 			}
 			System.err.println(">> "
-					+ (pass ? "PASS" : "FAIL") + "\t"
+					+ (pass ? "PASS" : "FAIL") + '\t'
 					+ clsName
 					+ (msg == null ? "" : "\t - " + msg));
 			if (exc != null) {

jadx-samples/src/main/java/jadx/samples/TestStringProcessing.java

@@ -12,7 +12,7 @@ public class TestStringProcessing extends AbstractTest {
 
 	public void testStringConcat() {
 		String s = "1";
-		assertEquals("a" + s, "a1");
+		assertEquals('a' + s, "a1");
 	}
 
 	@Override