diff --git a/d2j-jasmin/src/main/java/com/googlecode/d2j/jasmin/JasminDumper.java b/d2j-jasmin/src/main/java/com/googlecode/d2j/jasmin/JasminDumper.java
index 198ccd095..a6f64df99 100644
--- a/d2j-jasmin/src/main/java/com/googlecode/d2j/jasmin/JasminDumper.java
+++ b/d2j-jasmin/src/main/java/com/googlecode/d2j/jasmin/JasminDumper.java
@@ -870,19 +870,19 @@ protected void printAnnotationArrayValue(final Object value) {
     }
 
     protected void printFrameType(final Object type) {
-        if (type == Opcodes.TOP) {
+        if (Opcodes.TOP.equals(type)) {
             pw.print("Top");
-        } else if (type == Opcodes.INTEGER) {
+        } else if (Opcodes.INTEGER.equals(type)) {
             pw.print("Integer");
-        } else if (type == Opcodes.FLOAT) {
+        } else if (Opcodes.FLOAT.equals(type)) {
             pw.print("Float");
-        } else if (type == Opcodes.LONG) {
+        } else if (Opcodes.LONG.equals(type)) {
             pw.print("Long");
-        } else if (type == Opcodes.DOUBLE) {
+        } else if (Opcodes.DOUBLE.equals(type)) {
             pw.print("Double");
-        } else if (type == Opcodes.NULL) {
+        } else if (Opcodes.NULL.equals(type)) {
             pw.print("Null");
-        } else if (type == Opcodes.UNINITIALIZED_THIS) {
+        } else if (Opcodes.UNINITIALIZED_THIS.equals(type)) {
             pw.print("UninitializedThis");
         } else if (type instanceof Label) {
             pw.print("Uninitialized ");
diff --git a/dex-ir/src/main/java/com/googlecode/dex2jar/ir/TypeClass.java b/dex-ir/src/main/java/com/googlecode/dex2jar/ir/TypeClass.java
index cce8e60e1..f61f5df82 100644
--- a/dex-ir/src/main/java/com/googlecode/dex2jar/ir/TypeClass.java
+++ b/dex-ir/src/main/java/com/googlecode/dex2jar/ir/TypeClass.java
@@ -17,8 +17,8 @@ public enum TypeClass {
     IF("i"), //
     JD("w"); //
 
-    public String name;
-    public boolean fixed;
+    public final String name;
+    public final boolean fixed;
 
     TypeClass(String use, boolean fixed) {
         this.name = use;
diff --git a/dex-reader-api/src/main/java/com/googlecode/d2j/Visibility.java b/dex-reader-api/src/main/java/com/googlecode/d2j/Visibility.java
index e49dc4c1e..5f1a73b34 100644
--- a/dex-reader-api/src/main/java/com/googlecode/d2j/Visibility.java
+++ b/dex-reader-api/src/main/java/com/googlecode/d2j/Visibility.java
@@ -7,7 +7,7 @@ public enum Visibility {
 
     BUILD(0), RUNTIME(1), SYSTEM(2);
 
-    public int value;
+    public final int value;
 
     // int VISIBILITY_BUILD = 0;
     // int VISIBILITY_RUNTIME = 1;
diff --git a/dex-reader-api/src/main/java/com/googlecode/d2j/reader/InstructionFormat.java b/dex-reader-api/src/main/java/com/googlecode/d2j/reader/InstructionFormat.java
index 27f7d7392..65bc71363 100644
--- a/dex-reader-api/src/main/java/com/googlecode/d2j/reader/InstructionFormat.java
+++ b/dex-reader-api/src/main/java/com/googlecode/d2j/reader/InstructionFormat.java
@@ -68,7 +68,7 @@ public enum InstructionFormat {
 
     // kFmt3rmi(3), // [opt] inline invoke/range
 
-    public int size;
+    public final int size;
 
     InstructionFormat(int size) {
         this.size = size;
diff --git a/dex-reader-api/src/main/java/com/googlecode/d2j/reader/Op.java b/dex-reader-api/src/main/java/com/googlecode/d2j/reader/Op.java
index 1908ba0b3..66629d8c9 100644
--- a/dex-reader-api/src/main/java/com/googlecode/d2j/reader/Op.java
+++ b/dex-reader-api/src/main/java/com/googlecode/d2j/reader/Op.java
@@ -291,19 +291,19 @@ public enum Op implements CFG {
             K_INSTR_CAN_CONTINUE | K_INSTR_CAN_THROW | K_INSTR_INVOKE, true), //
     BAD_OP(-1, "bad-opcode", null, kIndexNone, 0, false); //
 
-    public int opcode;
+    public final int opcode;
 
-    public InstructionFormat format;
+    public final InstructionFormat format;
 
     /* package */ InstructionIndexType indexType;
 
     /* package */ int flags;
 
-    public String displayName;
+    public final String displayName;
 
     public static final Op[] OPS = new Op[256];
 
-    public boolean changeFrame;
+    public final boolean changeFrame;
 
     static {
         for (Op op : Op.values()) {
@@ -340,6 +340,7 @@ public boolean canThrow() {
         this.format = fmt;
         this.indexType = indexType;
         this.flags = flags;
+        this.changeFrame = changeFrame;
     }
 
     public String toString() {
diff --git a/dex-tools/src/main/java/com/googlecode/d2j/tools/jar/ClassInfo.java b/dex-tools/src/main/java/com/googlecode/d2j/tools/jar/ClassInfo.java
index 1e7e4abec..543d88867 100644
--- a/dex-tools/src/main/java/com/googlecode/d2j/tools/jar/ClassInfo.java
+++ b/dex-tools/src/main/java/com/googlecode/d2j/tools/jar/ClassInfo.java
@@ -3,6 +3,7 @@
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Objects;
 import java.util.Set;
 
 public class ClassInfo {
@@ -17,8 +18,16 @@ public ClassInfo(String name) {
         this.name = name;
     }
 
+    @Override
     public boolean equals(Object o) {
-        return name.equals(((ClassInfo) o).name);
+        if (this == o) {
+            return true;
+        }
+        if (!(o instanceof ClassInfo)) {
+            return false;
+        }
+        ClassInfo classInfo = (ClassInfo) o;
+        return Objects.equals(name, classInfo.name);
     }
 
     public int hashCode() {
diff --git a/dex-tools/src/main/java/com/googlecode/d2j/tools/jar/InitOut.java b/dex-tools/src/main/java/com/googlecode/d2j/tools/jar/InitOut.java
index b1b3d3f9f..7c1326baf 100644
--- a/dex-tools/src/main/java/com/googlecode/d2j/tools/jar/InitOut.java
+++ b/dex-tools/src/main/java/com/googlecode/d2j/tools/jar/InitOut.java
@@ -3,6 +3,7 @@
 import com.googlecode.dex2jar.tools.BaseCmd;
 import com.googlecode.dex2jar.tools.Constants;
 import java.io.IOException;
+import java.io.Serializable;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
@@ -448,7 +449,7 @@ private static class MemberInfo {
 
     }
 
-    private static class MemberInfoComparator implements Comparator<MemberInfo> {
+    private static class MemberInfoComparator implements Comparator<MemberInfo>, Serializable {
 
         @Override
         public int compare(MemberInfo memberInfo, MemberInfo memberInfo2) {
diff --git a/dex-tools/src/main/java/com/googlecode/dex2jar/tools/StdApkCmd.java b/dex-tools/src/main/java/com/googlecode/dex2jar/tools/StdApkCmd.java
index c5583b951..dc4fcc67b 100644
--- a/dex-tools/src/main/java/com/googlecode/dex2jar/tools/StdApkCmd.java
+++ b/dex-tools/src/main/java/com/googlecode/dex2jar/tools/StdApkCmd.java
@@ -27,7 +27,7 @@ protected void doCommandLine() throws Exception {
             return;
         }
 
-        System.err.printf("fix %s -> %s\n", remainingArgs[0], output);
+        System.err.printf("fix %s -> %s%n", remainingArgs[0], output);
 
         byte[] buffer = new byte[1000];
         try (ZipOutputStream zos = new AutoSTOREDZipOutputStream(Files.newOutputStream(output))) {
diff --git a/dex-writer/src/main/java/com/googlecode/d2j/dex/writer/item/SectionItem.java b/dex-writer/src/main/java/com/googlecode/d2j/dex/writer/item/SectionItem.java
index 0e9969431..109b60574 100644
--- a/dex-writer/src/main/java/com/googlecode/d2j/dex/writer/item/SectionItem.java
+++ b/dex-writer/src/main/java/com/googlecode/d2j/dex/writer/item/SectionItem.java
@@ -32,7 +32,7 @@ public static void main(String... strings) throws IllegalArgumentException, Ille
         for (Field f : SectionItem.class.getFields()) {
             if (f.getType().equals(int.class)) {
                 if (0 != (f.getModifiers() & Modifier.STATIC)) {
-                    System.out.printf("%s(0x%04x,0,0),//\n", f.getName(), f.get(null));
+                    System.out.printf("%s(0x%04x,0,0),//%n", f.getName(), f.get(null));
                 }
             }
         }
@@ -109,9 +109,9 @@ public enum SectionType {
         TYPE_ENCODED_ARRAY_ITEM(0x2005, 1, 0), //
         TYPE_ANNOTATIONS_DIRECTORY_ITEM(0x2006, 4, 0); //
 
-        public int code;
+        public final int code;
 
-        public int alignment;
+        public final int alignment;
 
         SectionType(int typeCode, int alignment, int size) {
             this.code = typeCode;