JAVA运算符(2021.11.20)

代码

package operator;

//导入这个包下所有的类！   阿里巴巴JAVA开发手册
import base.*;

public class Demo03 {
    public static void main(String[] args) {
        //与(and)    或(or)   非(取反)
        boolean a = true;
        boolean b = false;

        System.out.println("a && b:"+(a&&b));       //逻辑与运算：两个变量都为真，结果才为true
        System.out.println("a || b:"+(a||b));       //逻辑或运算：两个变量有一个为真，则结果为true
        System.out.println("!(a && b):"+!(a&&b));   //如果是真，则变为假，如果是假则变为真

        //短路运算
        int c = 5;
        boolean d = (c<4)&&(c++<4);
        System.out.println(d);
        System.out.println(c);

        System.out.println("===========================");
        
        System.out.println(2<<3);

        System.out.println("==========================");
        int e = 10;
        int f = 20;
        String g = "";
        e+=f; //e = e+f
        e-=f; //e = e-f
        g = e+f+"";
        System.out.println(e);

        System.out.println("===========================");
        //字符串连接符    +
        System.out.println(""+e+f); //结果为1020，前面字符串会导致后面全部变成运算符
        System.out.println((e+f+"").getClass()); //结果为30，后面是字符串，前面先加后在变成字符串

        System.out.println("=============================");
        //三元运算符 x ? y : z
        //如果x==true,则结果为y，否则结果为z
        int score = 80;
        String type = score < 60 ? "不及格":"及格";
        System.out.println(type);
    }
}