接口的声明与使用

computable.java

public interface computable {
	int MAX=100;
	int f(int x);
}

china.java

public class china implements computable{
	int number;
	public int f(int x){
		int sum=0;
		for(int i=1;i<=x;i++){
			sum=sum+i;
		}
		return sum;
	}
}

Japan.java

public class Japan implements computable{
	int number;
	public int f(int x){
		return 66+x;
	}
}

test.java

public class test {
	public static void main(String args[]){
		china zhang;
		Japan henlu;
		zhang=new china();
		henlu=new Japan();
		zhang.number=991898+computable.MAX;
		henlu.number=941448+computable.MAX;
	    System.out.println("number:"+zhang.number+"求和"+zhang.f(100));
	    System.out.println("number:"+henlu.number+"求和"+henlu.f(100));
	}
}