帮忙看看我的这个问题

[pengpeng5047]

想用java实现一个计算器，其中用到了栈，我的代码如下：
Calculate.java

import java.util.*;

class Calculate {
    private Stack<Character> sign = new Stack<Character>();
    private ArrayList<Character> list = new ArrayList<Character>();
    public void addToStack( char c ){
	    System.out.println("addToStack");
        sign.push( c );
		System.out.println("符号栈中元素个数为"+sign.size());
    }
	public void addToList( char c ){
	    System.out.println("addToList");
		list.add( c );
	}
	public void deleteChar(){
	System.out.println("deleteChar");
	}
	public void emptyStack(){
	    System.out.println("emptyStack");
		
	}
	public void emptyList(){
	System.out.println("emptyList");
	}
	public String result(){
	    return "结果";
    }	
}  

UI.java

import javax.swing.*;    
import java.awt.*;   

class UI {
    private JFrame myCalculate;
	private JPanel contentPanel;
	private JPanel buttonPanel;
	private JTextField result;
	private JButton bracketLeft;
	private JButton bracketRight;
	private JButton num0;
	private JButton num1;
	private JButton num2;
	private JButton num3;
	private JButton num4;
	private JButton num5;
	private JButton num6;
	private JButton num7;
	private JButton num8;
	private JButton num9;
	private JButton add;
	private JButton sub;
	private JButton mul;
	private JButton div;
	private JButton dot;
	private JButton equal;
	private JButton delete;
	private JButton empty;
	private Listener myListener;
	public UI(){
	    myCalculate = new JFrame("计算器");
		contentPanel = new JPanel();
		BorderLayout borderLayout = new BorderLayout();
		borderLayout.setVgap(20);
		contentPanel.setLayout(borderLayout);
		myCalculate.setContentPane(contentPanel);
		result = new JTextField(20);
		result.setEditable(false);
		bracketLeft = new JButton("(");
		bracketRight = new JButton(")");
		num0 = new JButton("0");
		num1 = new JButton("1");
		num2 = new JButton("2");
		num3 = new JButton("3");
		num4 = new JButton("4");
		num5 = new JButton("5");
		num6 = new JButton("6");
		num7 = new JButton("7");
		num8 = new JButton("8");
		num9 = new JButton("9");
		add = new JButton("+");
		sub = new JButton("-");
		mul = new JButton("×");
		div = new JButton("÷");
		dot = new JButton(".");
		equal = new JButton("=");
		delete = new JButton("删除");
		empty = new JButton("清空");
		myListener = new Listener();
		bracketLeft.addActionListener(myListener);
		bracketRight.addActionListener(myListener);
		num0.addActionListener(myListener);
		num1.addActionListener(myListener);
		num2.addActionListener(myListener);
		num3.addActionListener(myListener);
		num4.addActionListener(myListener);
		num5.addActionListener(myListener);
		num6.addActionListener(myListener);
		num7.addActionListener(myListener);
		num8.addActionListener(myListener);
		num9.addActionListener(myListener);
		add.addActionListener(myListener);
		sub.addActionListener(myListener);
		mul.addActionListener(myListener);
		div.addActionListener(myListener);
		dot.addActionListener(myListener);
		equal.addActionListener(myListener);
		delete.addActionListener(myListener);
		empty.addActionListener(myListener);
		buttonPanel = new JPanel();
		GridLayout gridLayout = new GridLayout(5,4);
		gridLayout.setHgap(10);
		gridLayout.setVgap(30);
		buttonPanel.setLayout(gridLayout);
		buttonPanel.add(bracketLeft);
		buttonPanel.add(bracketRight);
		buttonPanel.add(delete);
		buttonPanel.add(empty);
		buttonPanel.add(num7);
		buttonPanel.add(num8);
		buttonPanel.add(num9);
		buttonPanel.add(div);
		buttonPanel.add(num4);
		buttonPanel.add(num5);
		buttonPanel.add(num6);
		buttonPanel.add(mul);
		buttonPanel.add(num1);
		buttonPanel.add(num2);
		buttonPanel.add(num3);
		buttonPanel.add(sub);
		buttonPanel.add(equal);
		buttonPanel.add(dot);
		buttonPanel.add(num0);
		buttonPanel.add(add);
		contentPanel.add("North",result);
		contentPanel.add("Center",buttonPanel);
		myCalculate.setSize(300,350);
		myCalculate.setVisible(true);
		myCalculate.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
	}
	public void setString( String s ){
	    result.setText( s );
	}
	public void addString( String s ){
	    result.setText( result.getText() + s );
	}
	public void deleteChar(){
	    System.out.println("deleteChar");
	}
}

Listener.java

import java.awt.event.*;

class Listener implements ActionListener {
    private boolean isSign( char c ){
	    switch( c ){
		    case '(':
			case ')':
			case '+':
			case '-':
			case '×':
			case '÷':return true;
			default:return false;
		}
	}
	private boolean isNum( char c){
	    if( c >= '.'&&c <= '9')
		    return true;
		else
		    return false;
	}
    public void actionPerformed( ActionEvent e ){
	    Calculate myCalculate = new Calculate();
//	    System.out.println( e.getActionCommand() );
//		Main.calculate.setString( e.getActionCommand() );
        String button = e.getActionCommand();
		char c = (button.toCharArray())[0];
		if( isSign( c ) )
		    myCalculate.addToStack( c );//把符号添加到栈里
        else if( isNum( c ) ){
            Main.calculate.addString( button );//把操作数添加到文本框里
			myCalculate.addToList( c );//把操作数添加到输出序列中
        }
        else if( button.equals( "删除" ) ){
		    Main.calculate.deleteChar();
            myCalculate.deleteChar();
        }
        else if( button.equals( "清空" ) ){
            Main.calculate.setString("");
			myCalculate.emptyStack();
			myCalculate.emptyList();
        }	
        else if( c == '=' )
            Main.calculate.setString( myCalculate.result() );		
	}
}

Main.java

public class Main{
    static UI calculate;
    public static void main( String[] args ){
        calculate = new UI();
    }
}

当我在界面中按一个运算符按键（+,-,*,/和括号）时，我想把运算符存到Calculate中定义的栈中，当我按多个运算符后，栈中应该有多个元素，可是为什么我的Calculate类中的addToStack（）方法每次都输出“个数为1”呢？我看了半天没找出原因在哪里，旁观者清，请各位帮忙看看。

[loveofmylife]

class Listener implements ActionListener {
	Calculate myCalculate = new Calculate();//把这个Calculate对象设置为全局对象
    private boolean isSign( char c ){
        switch( c ){
            case '(':
            case ')':
            case '+':
            case '-':
            case '×':
            case '÷':return true;
            default:return false;
        }
    }
    private boolean isNum( char c){
        if( c >= '.'&&c <= '9')
            return true;
        else
            return false;
    }
    public void actionPerformed( ActionEvent e ){
        
//        System.out.println( e.getActionCommand() );
//        Main.calculate.setString( e.getActionCommand() );
        String button = e.getActionCommand();
        char c = (button.toCharArray())[0];
        if( isSign( c ) )
            myCalculate.addToStack( c );//把符号添加到栈里
        else if( isNum( c ) ){
            Main.calculate.addString( button );//把操作数添加到文本框里
            myCalculate.addToList( c );//把操作数添加到输出序列中
        }
        else if( button.equals( "删除" ) ){
            Main.calculate.deleteChar();
            myCalculate.deleteChar();
        }
        else if( button.equals( "清空" ) ){
            Main.calculate.setString("");
            myCalculate.emptyStack();
            myCalculate.emptyList();
        }    
        else if( c == '=' )
            Main.calculate.setString( myCalculate.result() );        
    }
}

你的代码中
public void actionPerformed( ActionEvent e ){
Calculate myCalculate = new Calculate();
...}这样写，你给事件注册句柄，每次调用这个句柄函数的时候都会new一个Calculate，改成上面那样就可以了

[pengpeng5047]

[Quote=引用 2 楼 viszl 的回复:]
Java codeclass Listenerimplements ActionListener {
Calculate myCalculate=new Calculate();//把这个Calculate对象设置为全局对象privateboolean isSign(char c ){switch( c ){case'(':case')':case'+':case'-':case'×':case'÷':returntrue;default:returnfalse;
}
}privateboolean isNum(char c){if( c>='.'&&c<='9')returntrue;elsereturnfalse;
}publicvoid actionPerformed( ActionEvent e ){// System.out.println( e.getActionCommand() );// Main.calculate.setString( e.getActionCommand() ); String button= e.getActionCommand();char c= (button.toCharArray())[0];if( isSign( c ) )
myCalculate.addToStack( c );//把符号添加到栈里elseif( isNum( c ) ){
Main.calculate.addString( button );//把操作数添加到文本框里 myCalculate.addToList( c );//把操作数添加到输出序列中 }elseif( button.equals("删除" ) ){
Main.calculate.deleteChar();
myCalculate.deleteChar();
}elseif( button.equals("清空" ) ){
Main.calculate.setString("");
myCalculate.emptyStack();
myCalculate.emptyList();
}elseif( c=='=' )
Main.calculate.setString( myCalculate.result() );
}
}
你的代码中
public void actionPerformed( ActionEvent e ){
        Calculate myCalculate = new Calculate();
...}这样写，你给事件注册句柄，每次调用这个句柄函数的时候都会new一个Calculate，改成上面那样就可以了

[/Quote]
呵呵，是这么回事，多谢了。

[whpeng2110]

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