问Java比较这个类和那个类是否相等

EN

  public boolean equals(java.lang.Object o){
  if(o == this) return true;
  if(o == null || !(o instanceof Stack12)){
     return false;
  }

  Stack12<E> that = (Stack12<E>)o;
  if(this.size != that.size || this.capacity != that.capacity ){
     return false;
  }
  for(int i = 0; i < this.size; i++){
     if( that.stack[i] != this.stack[i] ){
        return false;
     }
  }
  return true;
 }