JAVA规范学习——String字面常量
package testPackage;
class Test {
public static void main(String[] args) {
String hello = "Hello", lo = "lo";
System.out.print((hello == "Hello") + " ");
System.out.print((Other.hello == hello) + " ");
System.out.print((other.Other.hello == hello) + " ");
System.out.print((hello == ("Hel"+"lo")) + " "); //(1)
System.out.print((hello == ("Hel"+lo)) + " "); //(2)
System.out.println(hello == ("Hel"+lo).intern());
}
}
class Other { static String hello = "Hello"; }
package other;
public class Other { static String hello = "Hello"; }
运行结果如下：
true true true true false true
结果解释：
1. 所有String字面量，不管其所在的class和package，都是同一个String对象的引用
2. 对于常量表达式计算的String，都是在编译期间计算的，被当作String字面量看待。例如(1)行所在的代码
3. 对于在运行期连接的String，都是新创建的，因此不相同。例如(2)行所在的代码
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