issues around null values

[[Split portion of a mixed commit.]]

src/org/objectweb/asm/util/CheckClassAdapter.java

@@ -215,7 +215,7 @@ public class CheckClassAdapter extends ClassAdapter {
                 + Opcodes.ACC_ANNOTATION + Opcodes.ACC_ENUM
                 + Opcodes.ACC_DEPRECATED);
         CheckMethodAdapter.checkInternalName(name, "class name");
-        if (name.equals("java/lang/Object")) {
+        if ("java/lang/Object".equals(name)) {
             if (superName != null) {
                 throw new IllegalArgumentException("The super class name of the Object class must be 'null'");
             }
@@ -226,7 +226,7 @@ public class CheckClassAdapter extends ClassAdapter {
             // TODO
         }
         if ((access & Opcodes.ACC_INTERFACE) != 0) {
-            if (!superName.equals("java/lang/Object")) {
+            if (!"java/lang/Object".equals(superName)) {
                 throw new IllegalArgumentException("The super class name of interfaces must be 'java/lang/Object'");
             }
         }

src/org/objectweb/asm/util/TraceMethodVisitor.java

@@ -286,11 +286,7 @@ public class TraceMethodVisitor extends TraceAbstractVisitor implements
         buf.setLength(0);
         buf.append(tab2).append("LDC ");
         if (cst instanceof String) {
-            if (cst == null) {
-                buf.append("null");
-            } else if (cst instanceof String) {
-                AbstractVisitor.appendString(buf, (String) cst);
-            }
+            AbstractVisitor.appendString(buf, (String) cst);
         } else if (cst instanceof Type) {
             buf.append(((Type) cst).getDescriptor() + ".class");
         } else {
@@ -479,7 +475,7 @@ public class TraceMethodVisitor extends TraceAbstractVisitor implements
      * 
      * @param l a label.
      */
-    protected void appendLabel(final Label l) {
+    public void appendLabel(final Label l) {
         String name = (String) labelNames.get(l);
         if (name == null) {
             name = "L" + labelNames.size();