如何顯示從TextField到TextArea的輸入字符串？

Question

我有JTextField和JTextArea 。 我想得到這樣的東西：TextField <-在這里輸入字符串。 然后單擊“回車”，該字符串應在“文本區域”中打印。 也許這是一個不好的想法，我應該使用其他組件。 我剛開始使用JFrame。

這是TextField代碼：

private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
   String text =  textField.getText();
   textArea.setText(text);
} 

它引發了數百萬個錯誤。 我是否應該添加“按下按鍵時”之類的內容？

我做了一些更改：setText（）由append代替，我制作了TextField和TextArea的對象。

package chatter;

import java.awt.Event;
import java.awt.TextArea;
import java.awt.TextField;

public class GUIFrame extends javax.swing.JFrame {


    public GUIFrame() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jButton2 = new javax.swing.JButton();
        jTextField1 = new javax.swing.JTextField();
        jScrollBar1 = new javax.swing.JScrollBar();
        jButton1 = new javax.swing.JButton();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jMenuBar1 = new javax.swing.JMenuBar();
        jMenu1 = new javax.swing.JMenu();
        jMenu2 = new javax.swing.JMenu();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton2.setText("jButton1");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        jTextField1.setText("jTextField1");
        jTextField1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField1ActionPerformed(evt);
            }
        });

        jButton1.setText("jButton1");

        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        jMenu1.setText("File");
        jMenuBar1.add(jMenu1);

        jMenu2.setText("Edit");
        jMenuBar1.add(jMenu2);

        setJMenuBar(jMenuBar1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(179, 179, 179)
                        .addComponent(jButton2)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jButton1)
                        .addGap(0, 193, Short.MAX_VALUE))
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                        .addContainerGap()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jTextField1)
                            .addComponent(jScrollPane1))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jScrollBar1, javax.swing.GroupLayout.PREFERRED_SIZE, 17, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton2)
                    .addComponent(jButton1))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 28, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 8, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(jScrollBar1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 371, Short.MAX_VALUE))
                .addGap(167, 167, 167))
        );

        pack();
    }// </editor-fold>                        



    TextField textField = new TextField();
    TextArea textArea = new TextArea();
;    

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
    }                                        

    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
       String text =  textField.getText();
       textArea.append(text);

    }                                           





    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(GUIFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(GUIFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(GUIFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(GUIFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new GUIFrame().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JMenu jMenu1;
    private javax.swing.JMenu jMenu2;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JScrollBar jScrollBar1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration                   
}

現在它不會引發錯誤，但是在TextArea中仍然沒有任何顯示。

Answer 1

將您的jTextField1ActionPerformed方法更改為：

private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
   String text =  jTextField1.getText();
   jTextArea1.append(text);
}

使用jTextField1代替textField並且文本區域相同。 您正在引用未使用的字段。 您應該同時刪除它們：

TextField textField = new TextField();
TextArea textArea = new TextArea();

Answer 2

問題是您有兩個TextField對象（ textField和jTextField1 ）和兩個TextArea對象（ textArea和jTextArea1 ）。 您已將jTextArea1 jTextField1和jTextArea1添加到了JFrame ，但是您的偵聽器使用的textArea和textField都沒有添加到框架中。 要解決此問題，請按以下方式更改您的方法：

private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {
   String text =  jTextField1.getText();
   jTextArea1.append(text);

}

似乎可以刪除textArea和textField 。