请大家帮我写下  大整数相加程序。我刚学 不怎么会，，

  随机生成两个100位以内的大整数，将两个数相加。 并格式化输出，  例如：每50位一行，5位一段。。

在控制台下输出就行！！不要求界面！。
 我就写出了一点，  剩下的不会了， 请大家帮忙！谢谢大家啦！！（我写的代码如下）

import java.util.Random;
public class Xangjia
{

  
    public static void main(String[] args)
    {
        
        Random Rnd=new Random();
        
        int L=0;
        int L2=0;
        int max;
        int min;
        while(L ==0)
        {
           L=Rnd.nextInt(100);
          
        }
        while(L2 ==0)
        {
           L2=Rnd.nextInt(100);
          
        }
    
    
        System.out.println("生成的位数为"+L); // 生成随机位数！
        System.out.println("生成的第2个数的位数为"+L2);
    
        int number[]=new int[L]; 
        int number2[]=new int[L2];    
            
        
        for(int i=0;i<L;i++)
        {
           number[i]=Rnd.nextInt(10);  
           
           System.out.print(number[i]);
        }
        
        System.out.print("\n");
        System.out.print("\n"+"〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓"+"\n");
        System.out.print("\n");
    
        for(int ii=0;ii<L2;ii++)
        {
           number2[ii]=Rnd.nextInt(10);  
           
           System.out.print(number2[ii]);
            
        }
        System.out.print("\n");
    
        
  
    
    
}   
}

已经差不多了.
再把2个数组中的元素分别相加就得了.记得进位.

思想我知道，  关键是不知道  写出来，，  一直出错！！   请帮帮我好吗？

有没有试试 BigInteger 或是 BigDecimal 呢？！

很好的一个类啊

要充分利用！

若不写界面的话10行左右的代码就可以了吧


import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.math.BigInteger;
import javax.swing.text.AttributeSet;   
import javax.swing.text.BadLocationException;   
import javax.swing.text.PlainDocument;

public class Bigint extends JFrame{
    private Container container;
    private JTextField num1,num2,sum;
    private JPanel panel,panel1;
    private JButton add;
    private BigInteger big1,big2,big3;
    
    public Bigint(){
        container = getContentPane();
        num1 = new JTextField(100);
        num1.setDocument(new NumOnly());
        num2 = new JTextField(100);
        num2.setDocument(new NumOnly());
        sum = new JTextField(101);
        sum.setEditable(false);
        panel = new JPanel();
        panel.setLayout(new GridLayout(3,1,5,5));
        panel.add(num1);
        panel.add(num2);
        panel.add(sum);
        container.add(new JScrollPane(panel));
        panel1 = new JPanel(new FlowLayout());
        add = new JButton("计算");
        add.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    if(num1.getText().equals("")||num2.getText().equals("")){
                        JOptionPane.showMessageDialog(container,"您没有输入完要计算的内容","提示",JOptionPane.INFORMATION_MESSAGE);
                    }
                    else{
                        big1 = new BigInteger(num1.getText());
                        big2 = new BigInteger(num2.getText());
                        big3 = big1.add(big2);
                        sum.setText(big3.toString());
                    }
                }
            }
        );
        panel1.add(add);
        container.add(panel1,BorderLayout.SOUTH);
        
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        Dimension frameSize = getSize();
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setLocation((screenSize.width-frameSize.width)/2,(screenSize.height-frameSize.height)/2);
        setVisible(true);
    }
    
    public static void main(String args[]){
        Bigint big = new Bigint();
    }
    
    public class NumOnly extends PlainDocument{        
        public void insertString(int offs,String str,AttributeSet a) throws BadLocationException{   
            for(int i=0;i<str.length();i++){  
                if(str.charAt(i)<'0'||str.charAt(i)>'9'){   
                    return;   
                }
            }   
            super.insertString(offs,str,a);  
            
        }
    }  
}

[[it] 本帖最后由 freish 于 2008-4-27 00:48 编辑 [/it]]

若是要随机生成数
可以用BigInteger构造方法中的
BigInteger(int numBits, Random rnd) 方法
它构造一个随机生成的 BigInteger，它是在 0 到 (2^numBits - 1)（包括）范围内均匀分布的值。

格式化输出用String的toCharArray方法转换成字符数组，然后输出就简单了

控制台的


import java.math.BigInteger;
import java.util.Random;

public class Big{
    private static BigInteger num1,num2,sum;
    
    public Big(){
        num1 = new BigInteger(334,new Random());
        num2 = new BigInteger(334,new Random());
        sum = num1.add(num2);
    }
    public static void main(String args[]){
        Big b = new Big();
        System.out.println("加数一为：");
        output(num1);
        System.out.println("加数二为：");
        output(num2);
        System.out.println("和为：");
        output(sum);
    }
    
    private static void output(BigInteger big){
        if(big!=null){
            String out = big.toString();
            char cout[] = out.toCharArray();
            for(int i = 1;i<cout.length;i++){
                System.out.print(cout[i-1]);
                if(i%5 == 0){
                    System.out.print(" ");
                }
                if(i%50 == 0){
                    System.out.println();
                }
            }
        }
    }
}

以下是控制台输出：

Process started >>>
加数一为：
15017 64068 48275 66141 54800 47537 71245 01117 38511 04132
61067 94079 17924 39481 41010 70592 55799 50415 92719 25204
加数二为：
28065 62205 90443 05182 05963 86086 34338 07289 56251 18136
09135 57779 11284 63146 53178 17791 84368 60334 79702 35818
和为：
43083 26274 38718 71323 60764 33624 05583 08406 94762 22268
70203 51858 29209 02627 94188 88384 40168 10750 72421 61022
<<< Process finished.
================ READY ================

import java.util.Random;
public class Xangjia
{
    public static int control(int count)//格式控制
    {
        if(count%5 == 0)System.out.print(" ");
        if(count%50 == 0)System.out.println();
        count ++;
        return count;
    }
    public static void create(int n[],int len)//生成随机数
    {
        int count = 1;
        Random Rnd=new Random();
        for(int i=0;i<len;i++)
        {                 
           n[i]=Rnd.nextInt(10);            
           System.out.print(n[i]);
           count = control(count);
        }      
    }
    public static void add(int a[],int b[],int sum[],int sign[],int minlen)//相加
    {
        for(int i = 0; i < minlen; i++)
        {                        
            sum[sum.length - 1 - i] = a[a.length - 1 - i] + b[b.length - 1 - i];
            if(sum[sum.length - i - 1] > 9)
                {                    
                    sign[sign.length - 1 - i] += 1;                      
                    sum[sum.length - 1 - i] %= 10;
                }       
        }
    }
    public static void in(int sum[],int sign[])//进位
    {
            for(int i = 1, j = 0; i < sum.length; i++,j++)
              {
                sum[sum.length - 1 - i] += sign[sign.length - 1 - j];
                if(sum[sum.length - 1 - i] > 9)
                    {                        
                      sign[sign.length - 2 - j] += 1;                       
                      sum[sum.length - 1 - i] %= 10;
                    }
              }        
    }
    public static void output(int sum[])//输出
    {
        int count = 1;
        int i = 0;
        try//捕获当生成的随机数都为0时产生的异常
        {
            while(sum[i] == 0)//去除前面是0的数
            i++;  
        }
        catch(Exception e){}                
        while(i < sum.length)//输出结果
        {
            System.out.print(sum[i]);
            count = control(count);
            i++;
        }
    }
    public static void main(String[] args)
    {  
        Random Rnd=new Random();      
        int L1=Rnd.nextInt(100);
        int L2=Rnd.nextInt(100);
        int max = L1>L2?L1:L2;
        int min = L1>L2?L2:L1;
        System.out.println("生成的第1个数的位数为"+L1);
        System.out.println("生成的第2个数的位数为"+L2);
        int a[] = new int[L1];
        int b[] = new int[L2];   
        int sum[] = new int[max+1];   
        int sign[] = new int[max];
        create(a,L1);
        System.out.println("\n"+"〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓");
        create(b,L2);
        System.out.println("\n它们的和是:");        
        //数组复制,把位数大的数前面不用加的数先存起来
        if(L1 > L2)
            System.arraycopy(a, 0, sum, 1, (a.length - b.length));
        else
            System.arraycopy(b, 0, sum, 1, (b.length - a.length));
        add(a,b,sum,sign,min);
        in(sum,sign);
        output(sum);
     }   
}

这是顺着你(LZ)的思路写的.
如果没有什么特别要求的.还是7楼的容易实现.
只是BigInteger(int numBits, Random rnd) 方法生成的随机数的位数太接近.