@Override 把這個標簽 干掉！方法前添加這個便簽的意義你還沒學到，編譯器自己會自動生成，但是請你干掉他！

import java.util.Scanner;

public class Demo1 {

public void Area() {

// TODO Auto-generated method stub

Scanner a = new Scanner(System.in);

int w = a.nextInt();

Scanner b = new Scanner(System.in);

int l = b.nextInt();

double area = w*l;

System.out.println(area);

}

public void Cir() {

Scanner a = new Scanner(System.in);

int w = a.nextInt();

Scanner b = new Scanner(System.in);

int l = b.nextInt();

int cir = 2*(w+l);

System.out.println(cir);

}

}

你這部分代碼應該是沒問題，我補充了個main，執行了一下，可以執行，完整代碼：

//包名

package com.practice;

//導入Scanner

import java.util.Scanner;

public class HellWorld {

public static void main(String[] args) {

// TODO Auto-generated method stub

? ? ? ? HellWorld ?rec1 = new HellWorld();

? ? ? ? rec1.Area();

? ? ? ? rec1.Cir();

}

public void Area() {

// TODO Auto-generated method stub

Scanner a = new Scanner(System.in);

int w = a.nextInt();

Scanner b = new Scanner(System.in);

int l = b.nextInt();

double area = w*l;

System.out.println(area);

}

//@Override

public void Cir() {

// TODO Auto-generated method stub

Scanner a = new Scanner(System.in);

int w = a.nextInt();

Scanner b = new Scanner(System.in);

int l = b.nextInt();

int cir = 2*(w+l);

System.out.println(cir);

}

}