Which java keyword cannot be used inside the body of a static method?

Question

Which java keyword cannot be used inside the body of a static method, but may be used without problems in a non-static method?

Answer 1

But javac doesn't complain. So I was not partially wrong -- I was completely wrong.It's still better not to use the "this", though. When you explictly reference a static member via an instance reference (theFoo.bar or this.bar, as opposed to Foo.bar) the JLS requires a check that the reference is non-null. Clearly "this" is always non-null, but javac still puts in half of the check. Take the simple class public class Test {
    static int field;
    public void setField(int i) {this.field=i;}
    public void staticSetField(int i) {field=i;}
} and observe the bytecodes produced: $ javap -c Test
Compiled from "Test.java"
public class Test extends java.lang.Object{
static int field;
public Test();
  Code:
   0:   aload_0
   1:   invokespecial   #1; //Method java/lang/Object."<init>":()V
   4:   return
public void setField(int);
  Code:
   0:   aload_0
   1:   pop
   2:   iload_1
   3:   putstatic       #2; //Field field:I
   6:   return
public void staticSetField(int);
  Code:
   0:   iload_1
   1:   putstatic       #2; //Field field:I
   4:   return
}The JIT will get rid of it, but you may as well avoid the waste in the first place. (And if you really do want to check that the reference is non-null, do the check explicitly so that maintainers know it's intentional).