java 如何从其他类访问 jFrame 的组件？
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How to access components of jFrame from other class?
提问by Ajay Sainy
I have two classes, first one is NewJFrame.java. Its code is-
我有两个类，第一个是 NewJFrame.java。它的代码是——
package javaapplication10;
import java.awt.Label;
public class NewJFrame extends javax.swing.JFrame {
public NewJFrame() {
initComponents();
}
private void initComponents() {
jButton1 = new javax.swing.JButton();
f = new javax.swing.JTextField();
l = new java.awt.Label();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jButton1.setText("jButton1");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
l.setText("label1");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(139, 139, 139)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(f, javax.swing.GroupLayout.PREFERRED_SIZE, 76, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addComponent(l, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
.addContainerGap(185, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(f, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(jButton1)
.addGap(22, 22, 22)
.addComponent(l, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(186, Short.MAX_VALUE))
);
pack();
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
System.out.println("Calling");
NewClass1 n = new NewClass1();
n.st();
}
public static void main(String args[]) {
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(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new NewJFrame().setVisible(true);
}
});
}
protected javax.swing.JTextField f;
protected javax.swing.JButton jButton1;
protected java.awt.Label l;
}
I am using netbeans. Main lines of codes are -
我正在使用 netbeans。主要代码行是 -
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
System.out.println("Calling");
NewClass1 n = new NewClass1();
n.st();
}
and variables declaration
和变量声明
protected javax.swing.JTextField f;
protected javax.swing.JButton jButton1;
protected java.awt.Label l;
My second class is NewClass.java and its code is - package javaapplication10;
我的第二个类是 NewClass.java，它的代码是 - 包 javaapplication10;
import java.awt.Label;
public class NewClass1 extends NewJFrame{
public void st()
{
l.setText(f.getText());
}
}
what I want to do is to click on the button(jbutton1) and the text written in the textfield(f) must be set in the Label(l). When I am clicking on the button "Calling" is printed on the console but the text on Label is not changing. What is the problem? Please Help.
我想要做的是单击按钮（jbutton1），并且必须在标签（l）中设置文本字段（f）中写入的文本。当我单击按钮时，控制台上会打印“呼叫”，但标签上的文本没有改变。问题是什么？请帮忙。
采纳答案by Vishal K
Why not you directly change the text of JLabell? in following way:
你为什么不直接改变 的文本JLabell？通过以下方式：
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt)
{
System.out.println("Calling");
//NewClass1 n = new NewClass1();
//n.st();
l.setText(f.getText());
}
UPDATE
Ok here u go , if you wish to do it via child class:
更新
好的，你去吧，如果你想通过子类来做：
change jButton1ActionPerformedto this way:
改成jButton1ActionPerformed这样：
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt)
{
System.out.println("Calling");
NewClass1 n = new NewClass1(this);
n.st();
}
And Change the constructor of NewClassas follows:
并更改构造函数NewClass如下：
NewJFrame njf;
public NewClass(NewJFrame jf)
{
this.nfj = jf;
}
public void st()
{
nfj.l.setText(nfj.f.getText());
}
