關於String是值傳遞還是引用傳遞，talk is cheap, just show codes

public class Itv {
    static String ss = "kkkkkk";
    static String ss1 = new String("kkkkkk");
    public void change(String str, char ch[]){
        str = "kkkkkk";
        System.out.println(str == ss);//true
        System.out.println(str == ss1);//false
        System.out.println("------------------");
        str = new String("kkkkkk");
        System.out.println(str == ss);//false
        //這句其實是廢話 System.out.println(str == ss1);//false
        ch[0] = 'J';
    }
    public static void main(String[] args) {
        String str = new String("good");
        String fry = "good";
        System.out.println(str == fry);//false
        System.out.println("############");
        char[] ch = {'t','e','s','t'};
        Itv itv = new Itv();
        itv.change(str,ch);
        System.out.println("-----------------------------------------");
        itv.change(fry,ch);
        System.out.println(str+"---"+ Arrays.toString(ch));//good---[J, e, s, t]
        System.out.println(fry+"---"+ Arrays.toString(ch));//good---[J, e, s, t]
    }
}

根據輸出結果得出結論： 傳遞的的確是引用，在常量池中有了“kkkkkk”就直接指向此字串的地址，如果沒有就在常量池中開闢空間然後把地址給str

 

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