import java.applet.*;
import java.awt.*;
public class ex10_8 extends Applet{
int rows;
public static long fac(int n){
    long res=1;
    for(int k=2;k<=n;k++)
        res=res*k;
    return res;
}
public static long com(int n,int m){
    return fac(n)/(fac(n-m)*fac(m));
}
public void init(){
    rows=Integer.parseInt(getParameter("lines"));
}
public void paint(Graphics g){
    int x,y=10;
    for(int n=10;n<=rows;n++){
        x=10;
        for(int m=0;m<=n;m++){
            g.drawString(""+com(n,m), x, y);
            x=x+40;
        }
    y=y+20;}}}

在eclipse上运行时为什么显示没有初始化？空值转换

rows=Integer.parseInt(getParameter("lines"));
需要个初始化参数
eclipse中可以：右键-->Run as -->Run Configurations-->Parameters添加参数lines