如何从其他类访问jFrame的组件? [英] How to access components of jFrame from other class?
本文介绍了如何从其他类访问jFrame的组件?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有两个类，第一个是NewJFrame.java.它的代码是-
I have two classes, first one is NewJFrame.java. Its code is-
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;
}
我正在使用netbeans. 代码的主要行是-
I am using netbeans. Main lines of codes are -
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
System.out.println("Calling");
NewClass1 n = new NewClass1();
n.st();
}
和变量声明
protected javax.swing.JTextField f;
protected javax.swing.JButton jButton1;
protected java.awt.Label l;
我的第二个类是NewClass.java，其代码是- 包javaapplication10;
My second class is NewClass.java and its code is - package javaapplication10;
import java.awt.Label;
public class NewClass1 extends NewJFrame{
public void st()
{
l.setText(f.getText());
}
}
我要做的是单击按钮(jbutton1)，并且必须在Label(l)中设置在textfield(f)中编写的文本. 当我单击按钮时，控制台上会打印呼叫"，但标签"上的文本不会更改.问题是什么?请帮忙.
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.
推荐答案
为什么不直接更改JLabel l的文本?通过以下方式:
Why not you directly change the text of JLabel l? in following way:
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt)
{
System.out.println("Calling");
//NewClass1 n = new NewClass1();
//n.st();
l.setText(f.getText());
}
更新
好的，如果您想通过子类完成此操作，请转到这里:
UPDATE
Ok here u go , if you wish to do it via child class:
将jButton1ActionPerformed更改为这种方式:
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt)
{
System.out.println("Calling");
NewClass1 n = new NewClass1(this);
n.st();
}
并按如下所示更改NewClass的构造函数:
And Change the constructor of NewClass as follows:
NewJFrame njf;
public NewClass(NewJFrame jf)
{
this.nfj = jf;
}
public void st()
{
nfj.l.setText(nfj.f.getText());
}
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