要求

（1）如果遇到红灯，需要显示 红灯停
（2）如果遇到绿灯，需要显示 绿灯行
（3）如果遇到黄灯，需要显示 黄灯等一等

代码实现

	import java.util.Scanner;public class Test {public static void main(String[] args) {Led l1 = Led.RED;l1.setS1("红灯停");Led l2 = Led.GREED;l2.setS2("绿灯行");Led l3 = Led.YELLOW;l3.setS3("黄灯等一等");Scanner s = new Scanner(System.in);while (true){System.out.println("请输入灯光颜色（red/green/yellow）：");String a = s.nextLine();switch (a){case "red":System.out.println(l1.getS1());System.exit(0);break;case "green":System.out.println(l2.getS2());System.exit(0);break;case "yellow":System.out.println(l3.getS3());System.exit(0);break;default:System.out.println("请输入正确的灯颜色");}}}}enum Led{RED, GREED, YELLOW;private String s1;private String s2;private String s3;public String getS1() {return s1;}public void setS1(String s1) {this.s1 = s1;}public String getS2() {return s2;}public void setS2(String s2) {this.s2 = s2;}public String getS3() {return s3;}public void setS3(String s3) {this.s3 = s3;}}

运行结果