Thinking in Java笔记2

（第3章笔记）

 

package com;class Value{int i;}public class Test2 {public static void main(String[] args) {Integer n1 = new Integer(2);n1++;System.out.println("n1 = " + n1);Integer n2 = new Integer(1);System.out.println("1.n1 = " + n1 + "/tn2 = " + n2);n1 = n2;//操作句柄，类似指针，看下面输出，此时你n1这个句柄已丢失，稍后会被垃圾收集器清楚System.out.println("2.n1 = " + n1 + "/tn2 = " + n2);String s1 = new String("abc");String s2 = new String("abc");System.out.println("the result of s1==s2 is "+(s1==s2));//实际上比较的是句柄，可用s1.equals(s2)比较String s3 = "123";String s4 = "123";System.out.println("the result of s3==s4 is "+(s3==s4));//这是市主类型，非比较句柄Value v1 = new Value();Value v2 = new Value();v1.i = v2.i = 100;System.out.println("the result of v1.equals(v2) is " + (v1.equals(v2)));//注意！这里输出时false//int i,j; 写成i&&j或i||j是非法的，&&，||，!只用来修饰布尔型(不同于C/C++)float f1 = 1.2e-22f;//1.2e-22默认为double，所以必须加上f才能赋值给f1char c1 = 0x60;System.out.println("c1 = " + c1);for(int i=0;i<3;i++){System.out.println(i);continue;//不会跳过i++}}} 

 

运行结果：

 

n1 = 3
1.n1 = 3 n2 = 1
2.n1 = 1 n2 = 1
the result of s1==s2 is false
the result of s3==s4 is true
the result of v1.equals(v2) is false
c1 = `
0
1
2