（1）定义一个接口Compute含有一个方法int computer(int n,int m); （2）设计四个类分别实现此接口，完成+-*/运算 （3）设计一个类UseCompute，含有方法： public void useCom(Compute com, int one, int two) （4）设计一个测试类

package b;

public interface Computer {
int computer(int n,int m);

}

package b;

public class Jia implements Computer {

@Override
public int computer(int n, int m) {
int jia;
jia=m+n;
System.out.println(m+"+"+n+"="+jia);
return jia;
}

}

package b;

public class Jian implements Computer {

@Override
public int computer(int n, int m) {
int jian;
jian=m-n;
System.out.println(m+"-"+n+"="+jian);
return jian;
}

}

package b;

public class Jian implements Computer {

@Override
public int computer(int n, int m) {
int jian;
jian=m-n;
System.out.println(m+"-"+n+"="+jian);
return jian;
}

}

package b;

public class Cheng implements Computer {

@Override
public int computer(int n, int m) {
int cheng;
cheng=m*n;
System.out.println(m+"*"+n+"="+cheng);
return cheng;
}

}

package b;

public class Chu implements Computer {

@Override
public int computer(int n, int m) {
int chu;
chu=m/n;
System.out.println(m+"/"+n+"="+chu);
return chu;
}

}

package b;

public class UseComputer implements Computer {

@Override
public int computer(int n, int m) {

return 0;
}

public void useCom(Computer com, int n, int m)
{
com.computer(n, m);
}

}

package b;

public class TestComputer {

public static void main(String[] args) {
UseComputer m=new UseComputer();
Jia a=new Jia();
Jian b=new Jian();
Cheng c=new Cheng();
Chu d=new Chu();
m.useCom(a, 3, 5);
m.useCom(b, 3, 5);
m.useCom(c, 3, 5);
m.useCom(d, 3, 5);
}

}