import java.util.Scanner;public class Test { public static void main(String[] args) { System.out.println("請輸入x的值："); //提示從鍵盤輸入x Scanner scanner=new Scanner(System.in); String strx=scanner.next(); //獲取從鍵盤輸入的字串 int x=Integer.parseInt(strx); //把字串x 轉為整型x int y=0; if(x<0){ y=x; }else if(x<50){ y=3*x-2; }else if(x<100){ y=4*x+1; }else{ y=5*x; } System.out.println("y的值為："+y); }}