Name: tb29552 Date: 07/23/98


/*
 * If you run this with the jit, the output is:
 * equals = true
 * equals = true
 * equals = true
 * equals = true
 * equals = true
 *
 * Without the jit, the output is:
 * equals = false
 * equals = false
 * equals = false
 * equals = false
 * equals = false
 *
 * Basically, with the jit, an object can never say that
 * it's not equal to itself. The equals method never even
 * gets called when the references are equal. In most
 * cases this is okay, but it does limit how an object can
 * define equality. This actually caused me some
 * headaches and workarounds. I thought everyone might
 * find it interesting.
 *
 * I think the JIT is taking unwarranted liberties
 * here. Nowhere in the VM or language specs does it say
 * that the specification of a method can be used to
 * optimise it, in cases where that would change the
 * behaviour (except possibly for final methods in classes
 * that can be considered part of the VM, e.g. Object,
 * Class, etc.)
 */

public class JitTest {
  public boolean equals(Object other) {
      return false;
  }

  public static void main(String[] args) {
      JitTest test = new JitTest();
      for (int i = 0; i < 5; i++)
        System.out.println("equals = " + test.equals(test));
    }
}

(Review ID: 35397)
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