Tue Apr 15 11:25:47 CST 2008 面额:2Exception in thread "main" java.lang.NullP
interException
at Lottery.generate(Exam10_2.java:14)
at Exam10_2.main(Exam10_2.java:50)import java.util.Date;
import javax.swing.JOptionPane;class Lottery
{
int[] numArray;
void generate( )
{
//int k;
for(int i=0,k=0;i<7; )
{
numArray[i]=(int)(35*Math.random()+1);
for(;k<i;k++)
if(numArray[k]==numArray[i])break;
if(i==k)
i++;
}
}
void printTitle(int i)
{
System.out.println(" 中国福利彩票");
System.out.println(" 35选7");
System.out.print(new Date());
System.out.print(" "+"面额:"+2*i);
}
void printData()
{
//generate( );
for(int i=0;i<7;i++)
System.out.print(numArray[i]+" ");
}}
public class Exam10_2
{
public static void main(String[] args)
{
String str=JOptionPane.showInputDialog("请输入要投的注数:");
int n=Integer.parseInt(str);
Lottery lottery=new Lottery();
lottery.printTitle(n);
for(int i=0;i<n;i++)
{
lottery.generate( );
lottery.printData();
}
}
}
interException
at Lottery.generate(Exam10_2.java:14)
at Exam10_2.main(Exam10_2.java:50)import java.util.Date;
import javax.swing.JOptionPane;class Lottery
{
int[] numArray;
void generate( )
{
//int k;
for(int i=0,k=0;i<7; )
{
numArray[i]=(int)(35*Math.random()+1);
for(;k<i;k++)
if(numArray[k]==numArray[i])break;
if(i==k)
i++;
}
}
void printTitle(int i)
{
System.out.println(" 中国福利彩票");
System.out.println(" 35选7");
System.out.print(new Date());
System.out.print(" "+"面额:"+2*i);
}
void printData()
{
//generate( );
for(int i=0;i<7;i++)
System.out.print(numArray[i]+" ");
}}
public class Exam10_2
{
public static void main(String[] args)
{
String str=JOptionPane.showInputDialog("请输入要投的注数:");
int n=Integer.parseInt(str);
Lottery lottery=new Lottery();
lottery.printTitle(n);
for(int i=0;i<n;i++)
{
lottery.generate( );
lottery.printData();
}
}
}
你的这个numArray没有初始化大小。