ActionListener код срабатывает дважды

Question

Я сделал JButton и добавил ActionListner к нему, но код в общественном ничтожной actionPerformed (ActionEvent е) {} exectues twice.It печатает тест дважды, вместо того, чтобы просто once.Here мой код

JButton testbut=new JButton("Test"); 
ListenForButton2 l=new ListenForButton2(); 
testbut.addActionListener(l); 
private class ListenForButton2 implements ActionListener{ 
    @Override 
    public void actionPerformed(ActionEvent e) { 
     if(e.getSource() == testbut){System.out.println("tEST");}  
    } 
} 

Вот полный код, на случай, если это не эне. Похоже, проблема заключалась в добавлении к моей кнопке двух слушателей действий. "If (testbut.getActionListeners(). Length < 1)) testbut.addActionListener (l);" fixed it . Но вы можете найти, где я добавил два тестовых примера для проверки кнопки

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Dimension; 
import java.awt.Font; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.RenderingHints; 
import java.awt.Shape; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.geom.Arc2D; 
import java.awt.geom.CubicCurve2D; 
import java.awt.geom.Ellipse2D; 
import java.awt.geom.Line2D; 
import java.awt.geom.QuadCurve2D; 
import java.awt.geom.Rectangle2D; 
import java.awt.geom.RoundRectangle2D; 
import java.io.File; 
import java.io.IOException; 

import javax.imageio.ImageIO; 
import javax.swing.ImageIcon; 
import javax.swing.JButton; 
import javax.swing.JComponent; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 

public class Game extends JFrame { 

    JButton but1 = new JButton("MakeMoney"); 
    JButton button1 = new JButton("Current money"); 
    JButton testbut=new JButton("Make money"); 
    int money = 0; 
    double currentMoney; 
    String moneyString = ""; 
    String box1txt="Text for box one"; 
    String[] boxtext={"Newspaper Delivery","Car wash","Pizza Delivery","Donut shop","Shrimp boat","Hockey team","Movie Studio","Bank","Oil Company"}; 
    String[] prices={"60.00","720.00","8,640.00","103,680.00","1,244,160.00","14,929,920.00","179,159,040.00","2.149 billion","25.798 billion"}; 
    public static void main(String[] args) { 
     new Game(); 
    } 

    public Game() { 

     try { 
      this.setContentPane(new JLabel(new ImageIcon(ImageIO.read(new File("C:/Users/TPC/workspace/ProjectMoney/Resources/backgroundForApp.png"))))); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 

     this.setLayout(new BorderLayout()); 

     button1.setContentAreaFilled(false); 

     ListenForButton lforButton = new ListenForButton(); 
     but1.addActionListener(lforButton); 

     JPanel thePanel = new JPanel(); 
     thePanel.add(button1); 
     thePanel.add(but1); 
     //thePanel.add(testbut); 


     this.setSize(1042, 617); 
     this.setLocationRelativeTo(null); 
     this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     this.setTitle("Project Money"); 
     this.add(thePanel, BorderLayout.NORTH); 
     this.add(new DrawStuff(), BorderLayout.CENTER); 
     this.setResizable(true); 
     this.setVisible(true); 

     Sound sound1 = new Sound(); 
     String sound = "file:C:/Users/TPC/Downloads/sound.wav"; 
     sound1.playMusic(sound); 

    } 

    private class ListenForButton implements ActionListener { 

     public void actionPerformed(ActionEvent e) { 

      if (e.getSource() == but1) { 
       money += 10; 
       moneyString = Integer.toString(money); 
       button1.setText("$" + moneyString); 

      } 

     } 
    } 
private class ListenForButton2 implements ActionListener{ 

    @Override 
    public void actionPerformed(ActionEvent e) { 
     if(e.getSource() == testbut){System.out.println("tEST");} 

    } 



} 

    private class DrawStuff extends JComponent { 

     @Override 
     protected void paintComponent(Graphics g) { 
      super.paintComponent(g); 
      Graphics2D graph2 = (Graphics2D) g; 
      graph2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 










      Shape drawRoundRec = new RoundRectangle2D.Double(170,40,250,66,45, 45); 

      //first num xpos,secound num ypost,third num sirina,fourht num duzina 
int x1=170; int y1=40; int x2=250; int y2=66; int def=45; 
      Shape drawRoundRec2=new RoundRectangle2D.Double(x1,(y1+80),x2,y2,def,def); 
      Shape drawRoundRec3=new RoundRectangle2D.Double(x1,(y1+80+80),x2,y2,def,def); 
      Shape drawRoundRec4=new RoundRectangle2D.Double(x1,(y1+80+80+80),x2,y2,def,def); 
      Shape drawRoundRec5=new RoundRectangle2D.Double(x1,(y1+80+80+80+80),x2,y2,def,def); 
      Shape drawRoundRect6=new RoundRectangle2D.Double(x1+330,40,250,66,def, def); 
      Shape drawRoundRect7=new RoundRectangle2D.Double(x1+330,(y1+80),250,66,def, def); 
      Shape drawRoundRect8=new RoundRectangle2D.Double(x1+330,(y1+80+80),250,66,def, def); 
      Shape drawRoundRect9=new RoundRectangle2D.Double(x1+330,(y1+80+80+80),250,66,def, def); 
      Shape drawRoundRect10=new RoundRectangle2D.Double(x1+330,(y1+80+80+80+80),250,66,def, def); 

      graph2.setPaint(Color.BLACK); 



      graph2.setColor(Color.LIGHT_GRAY); 

      graph2.fill(drawRoundRec); graph2.fill(drawRoundRec2); 
      graph2.fill(drawRoundRec3); graph2.fill(drawRoundRec4); graph2.fill(drawRoundRec5); graph2.fill(drawRoundRect6); 
      graph2.fill(drawRoundRect7); graph2.fill(drawRoundRect8); graph2.fill(drawRoundRect9); graph2.fill(drawRoundRect10); 
      graph2.setPaint(Color.BLACK); 

      graph2.draw(drawRoundRec2); graph2.draw(drawRoundRec3); graph2.draw(drawRoundRec4); 
      graph2.draw(drawRoundRec5); graph2.draw(drawRoundRect6); graph2.draw(drawRoundRect7); graph2.draw(drawRoundRect8); 
      graph2.draw(drawRoundRect9); graph2.draw(drawRoundRect10); 
      Font font=new Font("Serif",Font.PLAIN,30); 
      g.setFont(font); g.drawString(box1txt,190,80); g.drawString(boxtext[0],190,150); g.drawString(boxtext[1],190,150+80); g.drawString(boxtext[2],190,150+90+70); 
      g.drawString(boxtext[3],190,150+90+70+80); 

      g.drawString(boxtext[4],520,80); g.drawString(boxtext[5],520,150); g.drawString(boxtext[6],520,150+80); g.drawString(boxtext[7],520,150+90+70); 
      g.drawString(boxtext[8],520,150+90+70+80); 



      g.drawString(prices[0],190,150+30); g.drawString(prices[1],190,150+80+30); g.drawString(prices[2],190,150+90+70+30); 
      g.drawString(prices[3],190,150+90+70+80+30); 

      g.drawString(prices[4],520,80+25); g.drawString(prices[5],520,150+30); g.drawString(prices[6],520,150+80+30); g.drawString(prices[7],520,150+90+70+30); 
      g.drawString(prices[8],520,150+90+70+80+30); 
      testbut.setLocation(180,70); 
      Dimension d = new Dimension(100,40); 
      testbut.setSize(d); 
      ListenForButton2 l=new ListenForButton2(); 
      if (testbut.getActionListeners().length<1) testbut.addActionListener(l); 







      this.add(testbut); 
     } 
    } 
} 

Answer 1

Обязательно добавьте слушателя действий только один раз.

Вы получаете количество слушателей через testbut.getActionListeners().length.

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Update - несколько вызовов

В paintComponent класса DrawStuff, который проходит JComponent вы только добавление слушателя раз. То же, что и для первого слушателя.

Разница в том, что первый добавляется внутри конструктора. Хотя метод paintComponent JComponent, который можно назвать кратным раз.

Что касается того, как и когда это называется, this answer может вам помочь.