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沒有重構equals方法時，兩個字符串對象的比較為何相等？

Java

qq_殺意隆_0 2018-04-12 11:23:33

//沒有重構equals方法。 //Cat.java public?class?Cat{} //Program.java public?class?Program{ ????public?static?void?main(String[]?args){ ????????Cat?cat1?=?new?Cat(); ????????Cat?cat2?=?new?Cat(); ????????System.out.println(cat1.equals(cat2));?//false ???????? ????????String?s1?=?new?String(); ????????String?s2?=?new?String(); ????????System.out.println(s1.equals(s2));?//?同樣是對象，此處為何是true?? ????} }

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3 回答

yanrun

TA貢獻317條經(jīng)驗獲得超240個贊

看一下String的源碼
public?boolean?equals(Object?anObject)?{
????????if?(this?==?anObject)?{
????????????return?true;
????????}
????????if?(anObject?instanceof?String)?{
????????????String?anotherString?=?(String)anObject;
????????????int?n?=?value.length;
????????????if?(n?==?anotherString.value.length)?{
????????????????char?v1[]?=?value;
????????????????char?v2[]?=?anotherString.value;
????????????????int?i?=?0;
????????????????while?(n--?!=?0)?{
????????????????????if?(v1[i]?!=?v2[i])
????????????????????????return?false;
????????????????????i++;
????????????????}
????????????????return?true;
????????????}
????????}
????????return?false;
????}

就是把兩個String轉換成字符串數(shù)組然后遍歷比較

反對回復 2018-04-12