一极菜的问题！我的程序运行完之后，输出一段表达式，如何从屏幕取得该完整的表达式？谢谢！！

Question

那也一样啊
StringBuffer s = new StringBuffer();s.add("第一次的输出");
...
s.add("第二次的输出");
...
s.add("最后一次的输出");
不就行了

Answer 1

那你看一下这个程序，如何按照你说的来实现
public class stack1{
         public static void main(String args[]){ 
          stackarray operator=new stackarray();
          String inorder=new String();
          int inposition=0;
          int operator1=0;
          System.out.println("please input the inorder expression");
          BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
          try{
          inorder=input.readLine();}
          catch(Exception e){
          System.out.println(e);}
          System.out.println("the postorder expression is");
         
   
         while (true){
          if(operator.isoperator(inorder.charAt(inposition))){
          if((operator.top==-1)||(char)inorder.charAt(inposition)=='(')
                     operator.push(inorder.charAt(inposition));
                  else
         
          //一段
          {   if((char)inorder.charAt(inposition)==')'){
                if(operator.astack[operator.top]!=40)
                   {operator1=operator.pop();
                       System.out.print((char)operator1);
          }
         }
          else
          {if(operator.priority(inorder.charAt(inposition))
          <=operator.priority(operator.astack[operator.top])
                         && operator.top!=-1)
                         {
                          operator1=operator.pop();
                          if(operator1!=40)
                          System.out.print((char)operator1);
                         }
                         operator.push(inorder.charAt(inposition));
                      }
                    }//一段
                }
               else
                System.out.print(inorder.charAt(inposition));
                int[] number=new int[20];
                number[inposition]=inorder.charAt(inposition);
                
                inposition++;
             if(inposition>=inorder.length())
                break;
              }
           while(operator.top!=-1)
            {
             operator1=operator.pop();
             System.out.print((char)operator1);
            }
        
       }
        
    }
    
    
    
      class stackarray{
         int maxsize=20;
         int[] astack=new int[maxsize];
         int top=-1;
         public void push(int value){
         int i;
         if(top>=maxsize)
         System.out.println("the stack is full");
         else{
         top++;
         astack[top]=value;
         }
         }
         public int pop(){
         int temp;
         int i;
         if(top<0){
         System.out.println("the stack is empty");
         return -1;
         }
         temp=astack[top];
         top--;
         return temp;
         }
         public boolean isoperator(int operator){
         if(operator==43||operator==45
         ||operator==42||operator==47
         ||operator==40||operator==41)
         return true;
         else
         return false;
         }
         public int priority(int operator){
         if(operator==43||operator==45||operator==40)
         return 1;
         else if(operator==42||operator==47)
         return 2;
         else
         return 0;
         }
        }

Answer 2

这就是你程序结构的问题了，你把显示逻辑和数据捆绑得太死了
最简单省事的解决办法就是定义一个变量（StringBuffer或Stack都行），每次System.out.println()时都把输出记录到这个变量中，为外部提供一个取这个私有变量值的方法

Answer 3

呵呵，Sorry，我一向很马虎的
马上改正：）

Answer 4

最简单的还是那样解决
加一个
private StringBuffer _result = new StringBuffer();
将每一个out都修改，如
System.out.print( yourString );
改为
System.out.print( yourString );
_result.add( yourString ); 
提供一个getResult()方法
public String getResult()
{
    return _result.toString();
}把你的main中的语句提到一个方法execute()中;
public void execute()
{
}
在main中的调用改为
    execute();
    String result = getResult();先进一点的方法你可以参看《设计模式》中的Interpreter

Answer 5

public class Stack1
{
    //~ Instance/static variables .............................................    private StringBuffer _result = new StringBuffer();    //~ Methods ...............................................................    public String getResult()
    {
        return this._result.toString();
    }    public static void main( String[] args )
    {
        execute();
    }    public void execute()
    {
        StackArray operator = new StackArray();
        String inorder = new String();
        int inposition = 0;
        int operator1 = 0;
        System.out.println( "please input the inorder expression" );        BufferedReader input = new BufferedReader( new InputStreamReader( 
                                                           System.in ) );        try
        {
            inorder = input.readLine();
        }
        catch ( Exception e )
        {
            System.out.println( e );
        }        System.out.println( "the postorder expression is" );        while ( true )
        {
            if ( operator.isoperator( inorder.charAt( inposition ) ) )
            {
                if ( ( operator.top == -1 ) || 
                     ( char ) inorder.charAt( inposition ) == '(' )
                {
                    operator.push( inorder.charAt( inposition ) );
                }
                else
                {
                    if ( ( char ) inorder.charAt( inposition ) == ')' )
                    {
                        if ( operator.astack[ operator.top ] != 40 )
                        {
                            operator1 = operator.pop();
                            System.out.print( ( char ) operator1 );
                            append( operator1 );
                        }
                    }
                    else
                    {
                        if ( operator.priority( inorder.charAt( inposition ) ) <= operator.priority( 
                                                                                          operator.astack[ operator.top ] ) && 
                             operator.top != -1 )
                        {
                            operator1 = operator.pop();                            if ( operator1 != 40 )
                            {
                                System.out.print( ( char ) operator1 );
                                append( operator1 );
                            }
                        }                        operator.push( inorder.charAt( inposition ) );
                    }
                } //一段
            }
            else
            {
                System.out.print( inorder.charAt( inposition ) );
                append( inorder.charAt( inposition ) );
            }            int[] number = new int[ 20 ];
            number[ inposition ] = inorder.charAt( inposition );
            inposition++;            if ( inposition >= inorder.length() )
            {
                break;
            }
        }        while ( operator.top != -1 )
        {
            operator1 = operator.pop();
            System.out.print( ( char ) operator1 );
            append( operator1 );
        }
    }    private void append( char ch )
    {
        _result.append( ch );
    }
}
class StackArray
{
    //~ Instance/static variables .............................................    int maxsize = 20;
    int top = -1;
    int[] astack = new int[ maxsize ];    //~ Methods ...............................................................    public boolean isoperator( int operator )
    {
        if ( operator == 43 || operator == 45 || operator == 42 || 
             operator == 47 || operator == 40 || operator == 41 )
        {
            return true;
        }
        else
        {
            return false;
        }
    }    public int pop()
    {
        int temp;
        int i;        if ( top < 0 )
        {
            System.out.println( "the stack is empty" );            return -1;
        }        temp = astack[ top ];
        top--;        return temp;
    }    public int priority( int operator )
    {
        if ( operator == 43 || operator == 45 || operator == 40 )
        {
            return 1;
        }
        else if ( operator == 42 || operator == 47 )
        {
            return 2;
        }
        else
        {
            return 0;
        }
    }    public void push( int value )
    {
        int i;        if ( top >= maxsize )
        {
            System.out.println( "the stack is full" );
        }
        else
        {
            top++;
            astack[ top ] = value;
        }
    }
}