how to compile java source code with assertion ?

[sam huang]

For Example(Dan's Mock Example):

 
class E {
  private boolean b1;
  private boolean b2;
  private boolean b3;
  public void setB1(boolean b) {b1 = b;}
  public void setB2(boolean b) {b2 = b;}
  public void setB3(boolean b) {b3 = b;}
  public void m1 (int i) {
    b2 = i % 2 == 0;
    if (!b3 & !b2 & !b1) {
      System.out.print("A");
    } else if (!b3 & !b2 & b1) {
      System.out.print("B");
    } else if (!b3 & b2 & !b1) {
      System.out.print("C");
    } else { // Only b3 is true.
      assert b3 & !b2 & !b1;
    }
    System.out.print(b1 + "," + b2 + "," + b3);
    b1 = b2 = b3 = false;
  }
  public static void main (String[] args) {
    E e = new E();
    e.setB1(true);
    e.m1(2);
  }
}

When I try to compile this code,I recieved the "Can't resolve symbol assert" error.

[John Paverd]

Compiling:
javac -source 1.4 E.java
Enabling assertions during execution:
java -ea E
Exception in thread "main" java.lang.AssertionError
at E.m1(E.java:17)
at E.main(E.java:25)