首先定义一个计算接口，定义加，减类实现数的加减法，在类里定义加减方法。添加构造函数在实例化时传入值。

public class de2 {
    
    	public static void main(String[] args) {
    		new add(5, 6).com();
    		new minus(4, 2).com();
    	}

}

interface computer {
	void com();
}

//加
class add implements computer {
	int a;
	int b;

	public add(int a, int b) {
		this.a = a;
		this.b = b;
	}

	@Override
	public void com() {
		System.out.println(a + b);
	}
}

// 减
class minus implements computer {
	int a;
	int b;

	public minus(int a, int b) {
		this.a = a;
		this.b = b;
	}

	@Override
	public void com() {
		System.out.println(a - b);
	}
}