程序检查出现了这个：Exception in thread "main" java.lang.NullPointerException

at test.Circle.setCircle(Circle.java:12)

at test.Circle.main(Circle.java:36)

程序：

package test;

import java.util.Scanner;

public class Circle {



/**

* @param args

*/

int[] centre=new int[2];

int r;

    public void setCircle()throws Exception{

    Circle[] a=new Circle[5];

    a[0].centre[0]=0;

    a[0].centre[1]=0;

a[0].r=1;

for(int i=1;i<5;i++){

System.out.println("***请输入第"+(i+1)+"个圆的信息：***");

Scanner input =new Scanner(System.in);

for(int j=0;j<2;j++){

System.out.println("圆心：");

a[i].centre[j]=input.nextInt();

}

System.out.println("半径：：");

a[i].r=input.nextInt();

}

Circle x=new Circle();

x.receiveCircle(a);

}

    public void receiveCircle(Circle[]a){

    for(int i=0;i<5;i++){

     System.out.println("圆心："+"("+a[i].centre[0]+","+a[i].centre[1]+")"+" "+"半径："+a[i].r);

    }

    }

public static void main(String[] args) throws Exception {

// TODO Auto-generated method stub

Circle y=new Circle();

y.setCircle();

}



}