StringAndFinal

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final回顾：

1.修饰类类不可被继承

2.修饰方法方法不能被重载

3.修饰变量变量引用不可变

4.需要程序员手动显示赋值

5.如果定义final变量时就为其进行初始化，则改变量在编译期间其值就已确定

实例1：

public class StringAndFinal{public static void main(String [] args){StringAndFinal saf = new StringAndFinal();System.out.println("action test1......");saf.test1();System.out.println("action test2......");saf.test2();}public void test1(){String s1 = "helloworld";String s2 = "hello" + "world";System.out.println("s1=s2? \t"+(s1 == s2));//trueString str1 = "hello";String str2 = "world";String s3 = str1 + str2;System.out.println("s1=s3? \t"+(s1 == s3)); //false}public void test2(){String s1 = "helloworld";String s2 = "hello" + "world";System.out.println("s1=s2? \t"+(s1 == s2));//truefinal String str1 = "hello";final String str2 = "world";String s3 = str1 + str2;System.out.println("s1=s3? \t"+(s1 == s3));//true}}

实例2：

public class FinalInitTest{final String str1;final String str2;final String str3 = "Java";//not static block{str1 = "Java";}public FinalInitTest(){str2 = "Java";}public void display(){System.out.println(str1 + str1 == "JavaJava");//falseSystem.out.println(str2 + str2 == "JavaJava");//falseSystem.out.println(str3 + str3 == "JavaJava");//true}public static void main(String[] args) {FinalInitTest fit = new FinalInitTest();fit.display();}}

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