Java CheckBox可選，但isSelected（）返回false

Question

所以我一直在尋找一個解決方案几個小時，但我找不到我的錯誤。 我使用循環創建了JCheckBoxes並將其添加到滾動面板。但是，如果我檢查它們，isSelected（）總是返回false。

import java.awt.Dimension; 
import java.awt.FlowLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.sql.SQLException; 
import java.util.ArrayList; 
import java.util.Collection; 

import javax.swing.Box; 
import javax.swing.BoxLayout; 
import javax.swing.JButton; 
import javax.swing.JCheckBox; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.JTextArea; 
import javax.swing.JTextField; 

public class Conn_Fak_GUI extends JFrame{ 
public static ArrayList<String> fields; 
public Conn_Fak cf; 
public ArrayList <JCheckBox> cb; 

public Conn_Fak_GUI() 
{ 
    this.setTitle("AMAG - Schnittstelle"); 
    this.setSize(500, 500); 
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    this.setLayout(null); 


    JLabel db_fak = new JLabel("Pfad zur Amicron - Datenbank: "); 
    db_fak.setBounds(10,10,200,20); 
    this.add(db_fak); 

    JTextArea input_db_fak = new JTextArea(); 
    input_db_fak.setBounds(10,30,300,20); 
    this.add(input_db_fak); 

    JLabel usernameinfo = new JLabel("Benutzername:"); 
    usernameinfo.setBounds(10,60,100,20); 
    this.add(usernameinfo); 

    JTextField username = new JTextField(); 
    username.setBounds(110,60,100,20); 
    this.add(username); 

    JLabel passwordinfo = new JLabel("Passwort:"); 
    passwordinfo.setBounds(10,80,100,20); 
    this.add(passwordinfo); 

    JTextField password = new JTextField(); 
    password.setBounds(110,80,100,20); 
    this.add(password); 


    JButton connect = new JButton("Verbinden"); 
    connect.setBounds(350,80,100,20); 
    connect.addActionListener(new ActionListener(){ 
     @Override 
     public void actionPerformed(ActionEvent e) 
     { 

      try { 
       cf = new 
    Conn_Fak(input_db_fak.getText(),username.getText(),password.getText()); 
      } catch (ClassNotFoundException | SQLException e1) { 
       // TODO Auto-generated catch block 
       e1.printStackTrace(); 
      } 
      try { 
       fields= cf.getFields(); 
       displayFields(); 
      } catch (SQLException e1) { 
       // TODO Auto-generated catch block 
       e1.printStackTrace(); 
      } 
      displayFields(); 
     } 
    }); 


    JButton export = new JButton("Exportieren"); 
    export.setBounds(350,360,100,20); 
    export.addActionListener(new ActionListener(){ 
     @Override 
     public void actionPerformed(ActionEvent e) 
     { 
      System.out.println(cb.get(1).isSelected()); 
      ExportData ed = new ExportData(fields,cf,cb); 
      try { 
       ed.exportToFile(); 
      } catch (SQLException e1) { 
       // TODO Auto-generated catch block 
       e1.printStackTrace(); 
      } 
     } 
    }); 
    this.add(export); 
    this.add(connect); 

    //FileChooser 
    JLabel ofile = new JLabel("Zieldatei: "); 
    ofile.setBounds(10,340,200,20); 
    this.add(ofile); 

    JTextArea input_ofile = new JTextArea(); 
    input_ofile.setBounds(10,360,300,20); 
    this.add(input_ofile); 

    this.setVisible(true); 
} 
public void displayFields() 
{ 
    JCheckBox jb; 
    cb = new ArrayList<JCheckBox>(); 


    for(int i = 0; i < fields.size(); i++) 
    { 
     jb = new JCheckBox(); 
     jb.setText(fields.get(i)); 
     cb.add(jb); 
    } 




    JPanel contentPane = new JPanel(); 
    JPanel listOfFiles = new JPanel(); 
    listOfFiles.setLayout(new BoxLayout(listOfFiles, BoxLayout.Y_AXIS)); 


    for(int i = 0; i < cb.size(); i++){ 
     listOfFiles.add(cb.get(i)); 
    } 

    JScrollPane jScrollPane = new JScrollPane(listOfFiles); 





    jScrollPane.setVerticalScrollBarPolicy 
    (JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); 
    jScrollPane.setPreferredSize(new Dimension (300, 200)); 
    contentPane.setBounds(10,120,300,200); 
    contentPane.add(jScrollPane); 

    this.add(contentPane); 
    this.revalidate(); 
    this.repaint(); 

} 


} 

import java.sql.SQLException; 
import java.util.ArrayList; 

import javax.swing.JCheckBox; 

public class ExportData { 
ArrayList <String> activatedFields; 
ArrayList <String> fields; 
ArrayList <JCheckBox> cb; 
Conn_Fak cf; 

public ExportData(ArrayList<String> fields, Conn_Fak cf,ArrayList<JCheckBox> 
cb){ 
    super(); 
    this.fields = fields; 
    this.cf = cf; 
    this.cb = cb; 
} 

public void exportToFile() throws SQLException{ 
    System.out.println(cb.size()); 
    if(!cb.get(1).isSelected()){ 
     System.out.println(cb.get(1)); 
    } 


    for(int i = 0; i < cb.size(); i++){ 
     if(cb.get(i).isSelected()){ 
      System.out.println(cb.get(i).getText()); 
      activatedFields.add(cb.get(i).getText()); 
     } 

    } 
    for(int j = 0; j < activatedFields.size();j++){ 
     System.out.println("+"+activatedFields.get(j)); 
    } 
    cf.getData(activatedFields); 


    } 


} 

我希望你能幫助我。如果你需要更多的代碼，我會發布它。

Answer 1

由於代碼不完整，您的問題不清楚。

但是我硬編碼ArrayList並創建了一些複選框。我做了很小的改變，爲我工作。

請參考代碼以下部分：

for(int i = 0; i < fields.size(); i++) 
{ 
    final String s = fields.get(i); 
    final JCheckBox jb = new JCheckBox(s);   

    jb.addActionListener(new ActionListener() { 

     @Override 
     public void actionPerformed(ActionEvent e) { 
      if(jb.isSelected()) 
       JOptionPane.showMessageDialog(getParent(), s +"Selected"); 

     } 
    }); 
    cb.add(jb); 
} 

工作的屏幕截圖：