1: public class U581 { 2: …… 3: // equals()만 구현 4: public boolean equals(Object obj) { 5: boolean ret; 6: if (obj != null) { 7: int i1 = this.hashCode(); 8: int i2 = obj.hashCode(); 9: if (i1 == i2) { ret = true; } 10: else { ret = false; } 11: } else { 12: ret = false; 13: } 14: return ret; 15: } 16: …… 17: }