The equals Method

• equals tests for equal contents
• == tests for equal location
• Used in many standard library methods
• Example: ArrayList.indexOf
  

  /** 
     Searches for the first occurrence of the given argument, 
     testing for equality using the equals method. 
     @param elem an object. 
     @return the index of the first occurrence 
     of the argument in this list; returns -1 if 
     the object is not found. 
  */ 
  public int indexOf(Object elem) 
  { 
     if (elem == null) 
     { 
        for (int i = 0; i < size; i++) 
           if (elementData[i] == null) return i; 
     } 
     else 
     { 
        for (int i = 0; i < size; i++) 
           if (elem.equals(elementData[i])) return i; 
     } 
     return -1; 
  }