计算随机抛1000次的骰子各个数字产生的概率。

import javax.swing.*;
public class Rate{
    public static void main(String[] args)
    {
        int a[]=new int[7],t=1000,x;
        while(t-->0)
        {
            x=(int)(Math.random()*6)+1;
            a[x]++;
        }
        JTextArea jj=new JTextArea("",2,10);
        for(int i=1;i<=6;i++){
            jj.setText("The number "+i+" has repeat "+a[i]+" times");
            jj.setEditable(false);
            JOptionPane.showMessageDialog(null,jj);
        }
        JOptionPane.showMessageDialog(null,"number 1: "+String.format("%.3f",a[1]/1000.0)+"\n"+"number 2: "+String.format("%.3f", a[2]/1000.0)+"\n"
                +"number 3: "+String.format("%.3f", a[3]/1000.0)+"\n"+"number 4: "+String.format("%.3f",a[4]/1000.0)+"\n"
                +"number 5: "+String.format("%.3f", a[5]/1000.0)+"\n"+"number 6: "+String.format("%.3f", a[6]/1000.0)+"\n",
                "1-6 出现的概率依次为：",JOptionPane.INFORMATION_MESSAGE);
    }
}

运行效果: