java中switch结构和 while for循环的用法

6.2 switch结构：   

变量可以是：variable can be:(mark: tried, can not be long)

char/int/short/byte（java1.7 就可以用String来switch了）

public class Test{

  public static void main(String[] args){

    double d1=0.0, d2=0.0;

    d1 = 11;

    d2 = 22;

    char o = '+';

    switch(o){

       case '+':

           System.out.println(d1+d2);

           break;

       case '-':

           System.out.println(d1-d2);

           break;

       case '*':

           System.out.println(d1*d2);

           break;

       case '/':

           System.out.println(d1/d2);

    }

  }

}

6.3 循环

6.3.1 while 循环

public class Test{

  public static void main(String[] args){

    int lim = 5;

    int sum = 0;

    int i = 1;

    while(i<=lim){

        sum =sum + i;

        i++;

    }

    System.out.println("sum = " + sum);

    int j = 1;

    while(j<=4){

        System.out.println("j=" + j);

        j++;

    }

    System.out.println(j);

  }

}

更多请见：https://blog.csdn.net/qq_43650923/article/details/101677108