JList가 JPanel 내에 나타나지 않습니다.

Question

저는 작업중인 프로그램을 약간 변경했습니다. 훌륭한 제안이있을 때 JScrollPanel 내의 JTextArea를 JList로 변경했습니다. 어떤 이유로 JList의 내용을 코딩 했더라도 영역은 공백으로 표시되고 약 1 행 높이 표시됩니다. 각 JList의 기본 크기는 (200, 200)으로 설정되어 있습니다. 어떤 아이디어?

코드 :

package SwingAssign2; 

import java.awt.Dimension; 
import java.awt.EventQueue; 

import javax.swing.BorderFactory; 
import javax.swing.DefaultListModel; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.JTextPane; 
import javax.swing.ListModel; 
import javax.swing.ListSelectionModel; 

import java.awt.BorderLayout; 

import javax.swing.JComboBox; 
import javax.swing.JTextField; 

import java.awt.FlowLayout; 

import javax.swing.SwingConstants; 

import java.awt.GridLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ItemEvent; 
import java.awt.event.ItemListener; 
import java.awt.event.MouseAdapter; 
import java.awt.event.MouseEvent; 

import javax.swing.DefaultComboBoxModel; 
import javax.swing.JList; 
import javax.swing.AbstractListModel; 

public class SwingAssign2 { 

    private JFrame frame; 
    private JTextField textField; 

    /** 
    * Launch the application. 
    */ 
    public static void main(String[] args) { 
     EventQueue.invokeLater(new Runnable() { 
      public void run() { 
       try { 
        SwingAssign2 window = new SwingAssign2(); 
        window.frame.setVisible(true); 
       } catch (Exception e) { 
        e.printStackTrace(); 
       } 
      } 
     }); 
    } 

    /** 
    * Create the application. 
    */ 
    public SwingAssign2() { 
     initialize(); 
     frame.pack(); 
    } 

    /** 
    * Initialize the contents of the frame. 
    */ 
    @SuppressWarnings("unchecked") 
    private void initialize() { 
     frame = new JFrame(); 
     frame.setSize(600, 500); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

     JPanel panelTop = new JPanel(); 
     FlowLayout fl_panelTop = (FlowLayout) panelTop.getLayout(); 
     fl_panelTop.setAlignment(FlowLayout.LEFT); 
     frame.getContentPane().add(panelTop, BorderLayout.NORTH); 
     //panel.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 5)); 

     final JComboBox comboBox = new JComboBox(); 
     comboBox.setModel(new DefaultComboBoxModel(new String[] {"Select Something", "Selection 1", "Selection 2", "Selection 3", "Selection 4"})); 
     panelTop.add(comboBox); 
     comboBox.setPreferredSize(new Dimension(160, 20)); 

     textField = new JTextField(); 
     panelTop.add(textField); 
     textField.setColumns(40); 
     textField.setBorder(BorderFactory.createLoweredBevelBorder()); 

     JPanel panelBottom = new JPanel(); 
     frame.getContentPane().add(panelBottom, BorderLayout.SOUTH); 
     panelBottom.setLayout(new BorderLayout(0, 0)); 

     final JLabel status = new JLabel("Status"); 
     status.setHorizontalAlignment(SwingConstants.CENTER); 
     panelBottom.add(status, BorderLayout.SOUTH); 
     status.setBorder(BorderFactory.createLoweredBevelBorder()); 

     JScrollPane scrollPaneB = new JScrollPane(); 
     scrollPaneB.setSize(200, 200); 
     String[] listB = { "Some content on the right panel", "More content", "Some more content", "More and more content", "More and more content", "More and more content", 
       "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", 
       "More and more content" }; 
     JList listBottom = new JList(listB); 
     listBottom.setVisibleRowCount(12); 
     scrollPaneB = new JScrollPane(listBottom); 
     panelBottom.add(scrollPaneB); 
     scrollPaneB.add(listBottom); 
     scrollPaneB.setBorder(BorderFactory.createTitledBorder("Bottom Panel")); 
     scrollPaneB.setVisible(true); 
     listBottom.setVisible(true); 

     JPanel panelCenter = new JPanel(); 
     frame.getContentPane().add(panelCenter, BorderLayout.CENTER); 
     panelCenter.setLayout(new GridLayout(0, 2, 0, 0)); 

     JScrollPane scrollPaneL = new JScrollPane(); 
     scrollPaneL.setSize(200, 200); 
     String[] listL = { "Some content on the right panel", "More content", "Some more content", "More and more content", "More and more content", "More and more content", 
       "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", 
       "More and more content" }; 
     JList listLeft = new JList(listL); 
     listLeft.setVisibleRowCount(12); 
     scrollPaneL = new JScrollPane(listLeft); 
     panelCenter.add(scrollPaneL); 
     scrollPaneL.add(listLeft); 
     scrollPaneL.setBorder(BorderFactory.createTitledBorder("Top Left Panel")); 
     scrollPaneL.setVisible(true); 
     listLeft.setVisible(true); 

     JScrollPane scrollPaneR = new JScrollPane(); 
     scrollPaneR.setSize(200, 200); 
     String[] listR = { "Some content on the right panel", "More content", "Some more content", "More and more content", "More and more content", "More and more content", 
       "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", "More and more content", 
       "More and more content" }; 
     JList listRight = new JList(listR); 
     listRight.setVisibleRowCount(12); 
     scrollPaneR = new JScrollPane(listRight); 
     panelCenter.add(scrollPaneR); 
     scrollPaneR.add(listRight); 
     scrollPaneR.setBorder(BorderFactory.createTitledBorder("Top Right Panel")); 
     scrollPaneR.setVisible(true); 
     listRight.setVisible(true); 






     comboBox.addItemListener(new ItemListener() { 
      @Override 
      public void itemStateChanged(ItemEvent e) { 
       if(e.getStateChange() == ItemEvent.SELECTED) { 
        textField.setText((String) comboBox.getSelectedItem()); 
        status.setText("comboBox Action Listener Fired"); 
       } 
      } 
     }); 


    } 

} 

Answer 1

당신은 JScrollPane의 및 JPanel의 모두에 JList의를 추가하고, 당신은 당신은 단지 하나 개의 컨테이너에 구성 요소를 추가 할 수 있음을 수행 할 수있는 권한이 없습니다. 여기서 JList를 각각의 JScrollPane에 추가 한 다음 JPanel에 JScrollPane을 추가하려고합니다.

---

또한, JScrollPane의 자체에하는 JList를 추가하지 않고, 당신은 스크롤 구획의 뷰포트에 목록을 추가 할 수 있습니다. JScrollPane의 생성자 통해

1. : new JScrollPane(myList)
2. 또는 방법을 통해이 보통 두 가지 방법 중 하나를 수행 또한 myScrollPane.setViewportView(myList)

   ---

• 난 당신이 호출 참조 setSize(...)을 코드에 넣으면됩니다.
• 명백한 목적을 위해 JScrollPane과 같은 구성 요소를 다시 구성하는 것 같습니다. 다시 말하지만, 당신도 이것을하고 싶지 않습니다.

---

수정 예
:

//!! JScrollPane scrollPaneB = new JScrollPane(); 
    //!! scrollPaneB.setSize(200, 200); 
    String[] listB = { "Some content on the right panel", "More content", 
     "Some more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content" }; 
    JList listBottom = new JList(listB); 
    listBottom.setVisibleRowCount(12); 
    JScrollPane scrollPaneB = new JScrollPane(listBottom); 
    panelBottom.add(scrollPaneB); 
    //!! scrollPaneB.add(listBottom); 
    scrollPaneB.setBorder(BorderFactory.createTitledBorder("Bottom Panel")); 
    scrollPaneB.setVisible(true); 
    // !! listBottom.setVisible(true); 

    JPanel panelCenter = new JPanel(); 
    frame.getContentPane().add(panelCenter, BorderLayout.CENTER); 
    panelCenter.setLayout(new GridLayout(0, 2, 0, 0)); 

    //!! JScrollPane scrollPaneL = new JScrollPane(); 
    // !! scrollPaneL.setSize(200, 200); 
    String[] listL = { "Some content on the right panel", "More content", 
     "Some more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content" }; 
    JList listLeft = new JList(listL); 
    listLeft.setVisibleRowCount(12); 
    JScrollPane scrollPaneL = new JScrollPane(listLeft); 
    panelCenter.add(scrollPaneL); 
    // !! scrollPaneL.add(listLeft); 
    scrollPaneL.setBorder(BorderFactory.createTitledBorder("Top Left Panel")); 
    // !! scrollPaneL.setVisible(true); 
    // !! listLeft.setVisible(true); 

    //!! JScrollPane scrollPaneR = new JScrollPane(); 
    //!! scrollPaneR.setSize(200, 200); 
    String[] listR = { "Some content on the right panel", "More content", 
     "Some more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content", "More and more content", 
     "More and more content" }; 
    JList listRight = new JList(listR); 
    listRight.setVisibleRowCount(12); 
    JScrollPane scrollPaneR = new JScrollPane(listRight); //!! 
    panelCenter.add(scrollPaneR); 
    //!! scrollPaneR.add(listRight); 
    scrollPaneR.setBorder(BorderFactory.createTitledBorder("Top Right Panel")); 
    //!! scrollPaneR.setVisible(true); 
    //!! listRight.setVisible(true);