其中一個Jbuttons的ActionListener不會被調用

Question

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.GridLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.ItemEvent; 
import java.awt.event.ItemListener; 
import javax.swing.ButtonGroup; 
import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JOptionPane; 
import javax.swing.JPanel; 
import javax.swing.JRadioButton; 
import javax.swing.JTextField; 



@SuppressWarnings("serial") 
public class Gui extends JFrame { 

private ExpPanel panel1; 
private Expression expression; 
private ColorPanel panel2; 
private SetValsPanel panel3; 
int xIndex; 
int cIndex; 

public Gui(){ 
    setLayout(new GridLayout(3,1,0,0)); 
    panel1 = new ExpPanel(); 
    panel2 = new ColorPanel(); 
    panel3 = new SetValsPanel(); 

    add(panel1); 
    add(panel2); 
    add(panel3); 

    panel1.setExp.addActionListener(
      new ActionListener() { 

       public void actionPerformed(ActionEvent arg0) { 
        String temp = panel1.setExp.getText(); 
        expression = new Expression(temp); 
        boolean[] isValid = expression.checkValid(); 
        if(isValid[0]){ 
         panel1.setExp.setText(expression.getExpression()); 
         panel1.valid.setText(""); 
         getContentPane().remove(panel2); 
         getContentPane().remove(panel3); 
         if (expression.getVars().length==0) 
          panel1.valid.setText("There's no variables in the entered expression."); 
         else if(expression.getVars().length==1){ 
          panel3 = new SetValsPanel(expression); 
          add(panel3); 

         } 
         else { 
         panel2 = new ColorPanel(expression); 
         add(panel2); 

        } 
        } 
        else { 


         if(!isValid[1]) 
          panel1.valid.setText("Invalid Expression (The prantheses don't match). Re-enter the expression."); 

         if(!isValid[3]) 
          panel1.valid.setText("Invalid Expression (The expression must not continue after the last pranthes OR Invalid function name). Re-enter the expression."); 

         if(!isValid[2]) 
          panel1.valid.setText("Invalid Expression (At least one argument of one of the functions is not entered). Re-enter the expression."); 

         if(!isValid[4]) 
          panel1.valid.setText("Invalid Expression (You've entered two arguments for a single argument function). Re-enter the expression."); 

         getContentPane().remove(panel2); 
         getContentPane().remove(panel3); 

        } 
        validate(); 
        repaint(); 
       } 
      } 
      ); 

    panel1.setbtn.addActionListener(
      new ActionListener() { 

       public void actionPerformed(ActionEvent arg0) { 
        System.out.println("in this shit"); 
        String temp = panel1.setExp.getText(); 
        expression = new Expression(temp); 
        boolean[] isValid = expression.checkValid(); 
        if(isValid[0]){ 
         panel1.setExp.setText(expression.getExpression()); 
         panel1.valid.setText(""); 
         getContentPane().remove(panel2); 
         getContentPane().remove(panel3); 
         if (expression.getVars().length==0) 
          panel1.valid.setText("There's no variables in the entered expression."); 
         else if(expression.getVars().length==1){ 
          panel3 = new SetValsPanel(expression); 
          add(panel3); 

         } 
         else { 
         panel2 = new ColorPanel(expression); 
         add(panel2); 

        } 
        } 
        else { 


         if(!isValid[1]) 
          panel1.valid.setText("Invalid Expression (The prantheses don't match or don't exist). Re-enter the expression."); 

         if(!isValid[3]) 
          panel1.valid.setText("Invalid Expression (The expression must not continue after the last pranthes OR Invalid function name). Re-enter the expression."); 

         if(!isValid[2]) 
          panel1.valid.setText("Invalid Expression (At least one argument of one of the functions is not entered). Re-enter the expression."); 

         if(!isValid[4]) 
          panel1.valid.setText("Invalid Expression (You've entered two arguments for a single argument function). Re-enter the expression."); 

         getContentPane().remove(panel2); 
         getContentPane().remove(panel3); 

        } 
        validate(); 
        repaint(); 
       } 
      } 
      ); 

    panel2.setbtn.addActionListener(
      new ActionListener() { 


       public void actionPerformed(ActionEvent arg1) { 
        if (panel2.cIndex == panel2.xIndex) 
         JOptionPane.showMessageDialog(null, "You can't choose the same variable for x-axis and color", "Error!", JOptionPane.ERROR_MESSAGE); 
        else { 
         String temp; 
         temp = expression.getVars()[xIndex]; 
         expression.setVars(xIndex,expression.getVars()[0]); 
         expression.setVars(0,temp); 
         temp = expression.getVars()[cIndex]; 
         expression.setVars(xIndex,expression.getVars()[1]); 
         expression.setVars(1,temp); 
         temp = null; 
         getContentPane().remove(panel3); 
         panel3 = new SetValsPanel(expression); 
         add(panel3); 
         validate(); 
         repaint(); 
        } 
       } 
      } 
      ); 

} 



} 


@SuppressWarnings("serial") 
class ExpPanel extends JPanel{ 

String expression; 
JTextField setExp; 
JButton setbtn; 
JLabel instruction; 
JLabel valid; 
boolean isValid; 
public ExpPanel(){ 

    setLayout(new GridLayout(2, 1, 5, 5)); 
    setExp = new JTextField(10); 
    setbtn = new JButton("Set");  
    instruction = new JLabel("Enter Expression : "); 
    valid = new JLabel("", JLabel.CENTER); 

    JPanel up = new JPanel(); 
    up.add(instruction,BorderLayout.WEST); 
    up.add(setExp,BorderLayout.CENTER); 
    up.add(setbtn,BorderLayout.EAST); 

    add(up); 
    add(valid); 

} 



} 

@SuppressWarnings("serial") 
class ColorPanel extends JPanel{ 

JButton setbtn = new JButton("Set"); 
JRadioButton[] xAxisbtns; 
JRadioButton[] colorbtns; 
int xIndex= -1; 
int cIndex = -1; 
public ColorPanel(){ 

} 

public ColorPanel(Expression a){ 
    int num = a.getVars().length; 
    xAxisbtns = new JRadioButton[num]; 
    colorbtns = new JRadioButton[num]; 
    ButtonGroup colorgroup = new ButtonGroup(); 
    ButtonGroup axisgroup= new ButtonGroup(); 
    setLayout(new GridLayout(4,1,0,0)); 
    JLabel instr = new JLabel("Select the variables for x-Axis and Color : ",JLabel.CENTER); 
    JPanel cPanel = new JPanel(); 
    JPanel xPanel = new JPanel(); 
    cPanel.setLayout(new GridLayout(1, num + 1, 1, 1)); 
    xPanel.setLayout(new GridLayout(1, num + 1, 1, 1)); 
    cPanel.add(new JLabel("Select the variable for Color :",JLabel.CENTER)); 
    xPanel.add(new JLabel("Select the variable for x-Axis :",JLabel.CENTER)); 
    for(int i =0;i<num;i++){ 
     xAxisbtns[i] = new JRadioButton(a.getVars()[i]);  
     colorbtns[i] = new JRadioButton(a.getVars()[i]); 
     colorgroup.add(colorbtns[i]); 
     axisgroup.add(xAxisbtns[i]); 
     xPanel.add(xAxisbtns[i]); 
     cPanel.add(colorbtns[i]); 
     xAxisbtns[i].addItemListener(new xhandler(i)); 
     colorbtns[i].addItemListener(new chandler(i)); 
    } 
    JPanel btnPanel = new JPanel(); 
    btnPanel.add(setbtn,JPanel.LEFT_ALIGNMENT); 
    add(instr); 
    add(xPanel); 
    add(cPanel); 
    add(btnPanel); 
} 

    private class xhandler implements ItemListener{ 
    private int index; 

    @Override 
    public void itemStateChanged(ItemEvent arg0) { 

     xIndex = index; 
    } 
    public xhandler(int i){ 
     index = i; 
    } 

} 

    private class chandler implements ItemListener{ 
    private int index; 

    @Override 
    public void itemStateChanged(ItemEvent arg0) { 

     cIndex = index; 
    } 
    public chandler(int i){ 
     index = i; 
    } 

} 
} 
@SuppressWarnings("serial") 
class SetValsPanel extends JPanel{ 

JTextField[][] vals; 
JButton drawIt = new JButton("Draw this shit"); 
JLabel[][] labels; 

public SetValsPanel(){ 

    drawIt.setEnabled(false); 

} 

public SetValsPanel(Expression a){ 

    int num = a.getVars().length; 
    vals = new JTextField[3][num]; 
    labels = new JLabel[3][num]; 
    JPanel[] rows = new JPanel[num]; 
    setLayout(new GridLayout(num+2,1,5,5)); 
    add(new JLabel("Set the Range and the inital value for each variable : ")); 
    for(int i=0;i<num;i++){ 
     labels[0][i] = new JLabel("Range for " + a.getVars()[i] + " :",JLabel.CENTER); 
     labels[1][i] = new JLabel(" to ",JLabel.CENTER); 
     labels[2][i] = new JLabel(" Inital value = " + a.getVars()[i] + " :",JLabel.CENTER); 
     vals[0][i] = new JTextField(3); 
     vals[1][i] = new JTextField(3); 
     vals[2][i] = new JTextField(3); 
     rows[i] = new JPanel(); 
     rows[i].setLayout(new GridLayout(1, 6, 2, 2)); 
     rows[i].add(labels[0][i]); 
     rows[i].add(vals[0][i]); 
     rows[i].add(labels[1][i]); 
     rows[i].add(vals[1][i]); 
     if (i!=0) { 
      rows[i].add(labels[2][i]); 
      rows[i].add(vals[2][i]); 
     } 
     add(rows[i]); 
    } 

    add(drawIt); 

} 

} 

第二個按鈕的Action偵聽器不起作用，而第一個actionlistener完美工作。我試圖通過將system.out添加到actionPerformed方法來檢查它是否被調用，從而向我顯示，當我單擊按鈕時actionlistener甚至不會被調用。

Edit = panel2.setbtn.addActionListener這是不起作用的。

編輯=這裏是表達類

public class Expression { 

private String expression; 
protected String[] vars; 
private String[] varValues; 

public Expression(String expression){ 

    this.expression = ExpressionFunctions.toValid(expression); 


    vars = new String[0]; 
    varValues = new String[0]; 

    extractVars(); 
} 

public void extractVars() { 

    String temp = expression; 
    temp = temp.toLowerCase(); 

    String[] names1 = {"div\\(" , "idiv\\(" , "mod\\(" , "pow\\("}; 
    String[] names2 = {"cotan\\(" , "arccos\\(" , "arccosh\\(" , "arcsinh\\(" , "cos\\(", "arccot\\(" , "arccoth\\(" , 
      "arcsin\\(" , "arcsinh\\(" , "arccosh\\(", "arctanh\\(" , "cosh\\(" , "exp\\(" , "ln\\(", "fact\\(" , 
      "fib\\(" , "sinh\\(" , "tanh\\(" }; 
    for(String x : names1) 
     temp = temp.replaceAll(x, "add\\("); 
    for(String x : names2) 
     temp = temp.replaceAll(x, "sin\\("); 

    EvalExperession a = new EvalExperession(temp, vars, varValues); 
    boolean rep = true; 


    while (rep) { 
     try { 
      a.run(); 
      rep = false; 
     } catch (IllegalArgumentException e) { 

      add(e.getMessage()); 

     a = new EvalExperession(temp, vars, varValues); 

     } 
    } 



} 

private void add(String message) { 
    String[] temp1 = new String[vars.length]; 
    String[] temp2 = new String[vars.length]; 
    for(int i =0;i<vars.length;i++){ 
     temp1[i] = vars[i]; 
     temp2[i] = varValues[i]; 
} 
    vars = new String[temp1.length+1]; 
    varValues = new String[temp2.length+1]; 
    for(int i =0;i<temp1.length;i++){ 
     varValues[i] = temp2[i]; 

     vars[i] = temp1[i];} 
    vars[temp1.length] = message; 
    varValues[temp1.length] = "1.0"; 

    temp1=null; 
    temp2 = null; 
} 

public String getExpression() { 
    return expression.toLowerCase(); 
} 

public void setExpression(String expression) { 
    this.expression = expression; 
} 

public String[] getVars() { 
    return vars; 
} 

public void setVars(int i,String a) { 
    this.vars[i] = a; 
} 

public String[] getVarValues() { 
    return varValues; 
} 

public void setVarValues(String[] varValues) { 
    this.varValues = varValues; 
} 

public boolean[] checkValid(){ 

    int right=0; 
    int left=0; 

    boolean[] res = new boolean[5]; 
    for (int i =0;i<5;i++) 
     res[i] = true; 



    for (int i=0; i<expression.length(); i++){ 



     if(expression.charAt(i) == '(') 
      left++; 
     if(expression.charAt(i) == ')') 
      right++; 
     if (right>left){ 
      res[0] = false; 
      res[1] = false; 
      return res;} 
    } 

    if (right!=left || (right == 0 && left == 0)) 
    { 
     res[0] = false; 
     res[1] = false; 
     return res;} 

    for (String x : vars){ 
     if((x + "a").equals("a") || x.indexOf("(")!= -1 || x.indexOf(",")!= -1 || x.indexOf(")")!= -1){ 
      if((x + "a").equals("a")){ 
       res[0] = false; 
       res[2] = false; 
       return res; 
      } 

      if(x.indexOf("(")!= -1 || x.indexOf(")")!= -1){ 

       res[0] = false; 
       res[3] = false; 
       return res; 
      } 

      if(x.indexOf(",")!= -1){ 
       res[0] = false; 
       res[4] = false; 
       return res; 
      } 

     } 

    } 

    return res; 

} 


} 

toValid功能簡單地糾正一個字符串，你可以忽略它。

Answer 1

這是我認爲正在發生的事情。在開始時，您使用ColorPanel（）創建一個ColorPanel，並將一個ActionListener添加到它的setbtn。

然後，在頂部面板中輸入表達式並按下其按鈕後，使用ColorPanel（字符串）創建一個新的ColorPanel。但是，新ColorPanel中的新setbtn不會被賦予ActionListener。

可能的quickie解決方案：向構造函數中添加一個Button參數，並將舊的setbtn傳遞給新實例。這將是快速和骯髒。

panel2 = new ColorPanel(expression, panel2.setbtn); 

在調用新是Panel2

，並

public ColorPanel(Expression a, JButton setbtn){ 
    this.setbtn = setbtn; 

在顏色面板

。這對我有效。

Answer 2

您絕不會將任何listener添加到drawIt按鈕。按照您對setbtn按鈕所做的操作。編譯器本身不會猜測它需要添加一個監聽器...

你可能要添加

SetValsPanel.drawIt.addActionListener(new ActionListener() { 
    public void actionPerformed(ActionEvent arg0) { 
    ... 
    } 
} 

Answer 3

建議：

• 您將要在閱讀和使用的CardLayout，讓您輕鬆交換JPanels或任何其他成分，將有助於簡化程序。
• 你可能不想創建和交換幾個SetValPanels，而對於ColorPanel也是如此。我敢打賭，你只是想創建一個，並在需要時交換它們。如果需要，確保將新的Expression對象傳遞到面板中，但是如果不需要，請避免創建和丟棄。這將有助於簡化代碼並避免ActionListener問題。
• 避免讓一個類直接操作其他類的字段，比如你的代碼在你有一個類的地方直接添加一個ActionListener給另一個類所持有的JButton，因爲這會增加連接/耦合。相反，將你的字段設置爲私有的，如果你打算允許其他類添加監聽器到一個包含的組件，給這個類一個公開的方法來達到這個目的。例如public void addSetBtnActionListener(ActionListener listener) {...}
• 也可以閱讀MVC中的Model-View-Control設計模式，因爲這樣可以幫助您減少代碼的複雜性。