java-day3

1、+ 号和字符串

package operator;

public class Demo05 {

    public static void main(String[] args) {
        int a = 10;
        int b = 20;

        System.out.println(a+b); //输出30
        System.out.println(""+a+b); //输出1020，将a和b拼接了
        System.out.println(a+b+""); //输出30  字符串在加法后面，所以会输出计算结果


    }

}

2、三元运算符

package operator;

public class Demo06 {
    public static void main(String[] args) {
        //x?y:z
        //如果x==true,结果为，否则结果为z
        int score = 50;
        String result = score<60?"不及格":"及格";
        System.out.println(result);
    }
}