选择结构
一,if的选择结构
1,if的单选择结构
单选择结构代码
public class Demo05 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("请输入内容:"); String s = scanner.nextLine(); if(s.equals("Hello liuliu")){ System.out.println(s); } System.out.println("end"); scanner.close(); } }
注意:equals:判断输入和if括号里面的条件是否相等,相等的话就输出,否则就不输出
2,if的双选择结构
双选择结构代码
public class Demo06 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("请输入您的成绩"); int score = scanner.nextInt(); if(score>60){ System.out.println("恭喜您及格啦!!!"); }else { System.out.println("不好意思啊,您挂科嘞,一分138,请重修!"); } scanner.close(); } }
3,if的多选择结构
多选择结构代码
public class Demo07 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("请输入您的成绩:"); int score = scanner.nextInt(); if(score==100){ System.out.println("恭喜您满分嘞"); }else if (score<100 && score>=90){ System.out.println("A级"); }else if (score<90 && score>=80){ System.out.println("B级"); }else if (score<80 && score>=70){ System.out.println("c级"); }else if (score<70 && score>=60){ System.out.println("D级"); }else if (score<60 && score>=0){ System.out.println("恭喜您挂科嘞"); }else { System.out.println("您输入的成绩不合法");} scanner.close(); } }
二,switch多选择结构
switch的代码示例
public class Demo08 { public static void main(String[] args) { char grade = 'A'; switch (grade){ case 'A': System.out.println("优秀"); break; case 'B': System.out.println("良好"); break; case 'C': System.out.println("还好"); break; case 'D': System.out.println("差劲"); break; default: System.out.println("未知等级"); } } }
注意
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break用于switch则终止switch
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default只有在case匹配失败的时候才会执行