operator4.java

《Java2程序设计实用教程(第2版)》课件

public class Operator4     //布尔运算,也称逻辑运算
{
    public static void main( String args []) 
    {
        System.out.println("!true = "+(!true));                  //逻辑非
        System.out.println("!false = "+(!false));
        System.out.println("true | false = "+(true | false));    //逻辑或
        System.out.println("true & false = "+(true & false));    //逻辑与
        System.out.println("true ^ false = "+(true ^ false));    //逻辑异或
        boolean b;                                               //b没有初值,不能输出
        System.out.println("true || b = "+(true || b));          //条件或,短路运算
        System.out.println("false && b= "+(false && b));         //条件与,短路运算
        int x=0,y=4,z=3;
        System.out.println("x="+x+",y="+y+",z="+z);
        System.out.println("x<y="+(x<y)+",y<z="+(y<z));          //比较运算结果是布尔值
        x=y=z=1;                                                 //可以连续赋值
        System.out.println("x="+x+",y="+y+",z="+z);
        System.out.println(++x & ++y & ++z);                     //位运算 
        System.out.println("x="+x+",y="+y+",z="+z);
    }
}

/*
程序运行结果：
!true = false
!false = true
true | false = true
true & false = false
true ^ false = true
true || b = true
false && b= false
x=0,y=4,z=3
x<y=true,y<z=false
x=1,y=1,z=1
2
x=2,y=2,z=2

没有^^运算,下列语句
        System.out.println("true ^^ false = "+(true ^^ false));  
产生编译错illegal start of expression

Java与C不同之处
        System.out.println("!a="+!a+",!b="+"!b");  //C中求反
Operator ! cannot be  applied to int
        
        System.out.println("a<b<c="+(a<b<c));      //C中连续比较
Operator < cannot be  applied to boolean,int

        System.out.println(++x || ++y && ++z);     //C中短路的逻辑运算
Operator || cannot be  applied to int,int

        x=1,y=2,z=3;                               //C中逗号运算符
';' expected
*/