Java 引用资料。 Java 是否对字符串文字进行特殊检查？

Question

public class Test {
    int multiple;
    public static void main(String[] args){

        String string1 = "string";
        String string2 = "string";
        String string4 = "Changed";

        String string3 = new String("string");

        System.out.println("string1 == string2: " + (string1 == string2));\\true
        System.out.println("string1 == string4: " + (string1 == string4));\\false
        System.out.println("string1 == string3: " + (string1 == string3));\\false

    }


}

我知道如果引用相同，== 运算符将返回 true。我想知道的是，Java 在创建对象之前是否检查字符串文字的内容？

Answer 1

您看到了 Java string interning 的副作用之一.来自 the JLS §3.10.5 :

...A string literal always refers to the same instance of class String. This is because string literals - or, more generally, strings that are the values of constant expressions (§15.28) - are "interned" so as to share unique instances, using the method String.intern.

Lots more reading on SO ，特别是:

• If == compares references in Java, why does it evaluate to true with these Strings?
• Java string intern and literal
• When is it beneficial to flyweight Strings in Java?
• How do I compare strings in Java?