java中JFrame类中 公共方法调用

Question

在NetBeans IDE 7.1.1中创建一个JFrame窗口程序。其中包含jTextField控件。现在需要在其他类中获取jTextField控件中的数据。
我是通过在JFrame中添加一个public方法，获取jTextField中的值。再到其他类中引用JFrame中的公共方法。结果在其他类中能获取jTextField中的初始值。更改后就不能即时的获取到了。
经测试：
JFrame中的public方法可以实时的获取jTextField中的值，但是经其他类一转，就变味了，这是咋解决啊、
代码如下:public class NewJFrame extends javax.swing.JFrame { /** * Creates new form NewJFrame */ public String getback()//这个就是公共方法 { String c; c = jTextField1.getText(); // System.out.println(c); return c; } public NewJFrame() { 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() { jTextField1 = new javax.swing.JTextField(); jButton1 = new javax.swing.JButton(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); jTextField1.setText("erg"); jTextField1.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { jTextField1ActionPerformed(evt); } }); jButton1.setText("jButton1"); jButton1.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { jButton1ActionPerformed(evt); } }); 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(156, 156, 156) .addComponent(jButton1)) .addGroup(layout.createSequentialGroup() .addGap(108, 108, 108) .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 160, javax.swing.GroupLayout.PREFERRED_SIZE))) .addContainerGap(132, Short.MAX_VALUE)) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGap(48, 48, 48) .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) .addGap(63, 63, 63) .addComponent(jButton1) .addContainerGap(145, Short.MAX_VALUE)) ); pack(); }// </editor-fold> private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) { // TODO add your handling code here: } private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { NewClass s = new NewClass();//newclass是新建其他的类，ee是其中的一个方法，只是打印。 s.ee(); // String m = getback(); // System.out.println(m); // TODO add your handling code here: } /** * @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(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); } //</editor-fold> /* * Create and display the form */ java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new NewJFrame().setVisible(true); } }); } // Variables declaration - do not modify private javax.swing.JButton jButton1; private javax.swing.JTextField jTextField1; // End of variables declaration } 
/*****************************其他类****************************/ public class NewClass { public void ee(){ NewJFrame j = new NewJFrame(); String k = j.getback(); System.out.println(k); // b = j.getback(); } } 

Answer 1

发的有点问题。http://topic.csdn.net/u/20120410/00/29ff4ea9-797d-44ca-bf8d-ce5076acc9ac.html
另外开的帖子。

Answer 2

public class A {
private B b;
public A(B b) {
this.b = b;
}
//这样的B就随便修改B里的值了
}
public class B {}

Answer 3

建议把改类的实例传过去，
在用该实例的getback(),不就行了？

Answer 4

持有对象引用？？
才接触java，怎么弄啊。
什么是持有对象引用？？

Answer 5

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 *//**
 *
 * @author xxl
 */
public class NewJFrame extends javax.swing.JFrame {
    private String c;//添加的    /**
     * Creates new form NewJFrame
     */
    public String getback()//添加的
    {
        //String c;
        //c = jTextField1.getText();
       // System.out.println(c);
        return  this.c = jTextField1.getText();//添加的
    }
    public NewJFrame() {
        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() {        jTextField1 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);        jTextField1.setText("erg");
        jTextField1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField1ActionPerformed(evt);
            }
        });        jButton1.setText("jButton1");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });        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(156, 156, 156)
                        .addComponent(jButton1))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(108, 108, 108)
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 160, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(132, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(48, 48, 48)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(63, 63, 63)
                .addComponent(jButton1)
                .addContainerGap(145, Short.MAX_VALUE))
        );        pack();
    }// </editor-fold>                            private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
    }                                               private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        NewClass  s = new NewClass();
        s.ee();
      // String m =  getback();
    //   System.out.println(m);
        // TODO add your handling code here:
    }                                            /**
     * @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(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);
        }
        //</editor-fold>        /*
         * Create and display the form
         */
        java.awt.EventQueue.invokeLater(new Runnable() {            public void run() {
                new NewJFrame().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration                   
}
//在这里引用上面getback（）方法
public class NewClass {
    public void ee(){
    NewJFrame j = new NewJFrame();
    String k = j.getback();
    System.out.println(k);
   // b = j.getback();
    }
    
}上面NewClass 中调用getback（）还是不成功，当public class NewJFrame里面jTextField1里面新输入的数据还是不能传到NewClass 中。
求解析。。还有持有对象引用，怎么弄啊。

Answer 6

    public JTextField getback()
    {
        return  this.jTextField1;
    }
这是对象引用

Answer 7

public class NewJFrame extends javax.swing.JFrame {
    private String c;    public String getback()
    {
        return  this.c = jTextField1.getText();
    }                        
.......
.......
.......
.......
.......    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
    }                                               private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        NewClass s = new NewClass();
        s.ee();
    }                                        .......
......
.....                   
}
public class NewClass {    private NewJFrame j;
    
    public NewClass(NewJFrame j)
    {
this.j = j;
    }
    public void ee(){
    String k = j.getback();
    System.out.println(k);
    }
    
}

Answer 8

在NewClass中你又New了一个新的NewJFrame类对象跟调用NewClass的那个NewJFrame对象不是一个，当然不能获取最开始的那个NewJFrame对象的JTextField的内容

Answer 9

 public JTextField getback()
    {
        return  this.jTextField1; }
//这个不行？    

Answer 10

//运行结果出现这个提示
/*run：
javax.swing.JTextField[,108,48,160x28,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=javax.swing.plaf.synth.SynthBorder@5660d6,flags=288,maximumSize=,minimumSize=,preferredSize=,caretColor=,disabledTextColor=DerivedColor(color=142,143,145 parent=nimbusDisabledText offsets=0.0,0.0,0.0,0 pColor=142,143,145,editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=DerivedColor(color=255,255,255 parent=nimbusSelectedText offsets=0.0,0.0,0.0,0 pColor=255,255,255,selectionColor=DerivedColor(color=57,105,138 parent=nimbusSelectionBackground offsets=0.0,0.0,0.0,0 pColor=57,105,138,columns=0,columnWidth=0,command=,horizontalAlignment=LEADING]
javax.swing.JTextField[,108,48,160x28,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=javax.swing.plaf.synth.SynthBorder@1a6684f,flags=288,maximumSize=,minimumSize=,preferredSize=,caretColor=,disabledTextColor=DerivedColor(color=142,143,145 parent=nimbusDisabledText offsets=0.0,0.0,0.0,0 pColor=142,143,145,editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=DerivedColor(color=255,255,255 parent=nimbusSelectedText offsets=0.0,0.0,0.0,0 pColor=255,255,255,selectionColor=DerivedColor(color=57,105,138 parent=nimbusSelectionBackground offsets=0.0,0.0,0.0,0 pColor=57,105,138,columns=0,columnWidth=0,command=,horizontalAlignment=LEADING]*/没有成功的。

Answer 11

我试了。还是有问题private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        NewClass  s = new NewClass();//这里提示说在NewClass里面没有构造函数，我自动添加了后。运行//成功了，但是传值的时候报错。大致在两处处，一处是构造函数，其次在jButton1ActionPerformed里面//NewClass  s = new NewClass()这里
        s.ee();
      // String m =  getback();
    //   System.out.println(m);
        // TODO add your handling code here:
    }               
你这个方法是上面原理呢。
以前我没有用过呢。

Answer 12

额，这样的啊，但是如果不new一个出来，怎么传那边的方法呢？求指点。具体是上面实现的额

Answer 13

楼主，我的意思是。
哎，
能把你用的那部分代码贴出来吗？
一个这么简单的引用，你可以用 s.getback().getText();
你只要把NewClass  s = new NewClass()
这个 s引用传到你要的那个界面。

Answer 14

   /*********JFrame 窗体类************/      
public class NewJFrame extends javax.swing.JFrame 
{
       /*********这个方法是获取输入框中的值，并返回（需要在其他类中使用）************/   
    public String getback()
    {
        return  this.jTextField1.getText();
    }
   /**********输入框jTextField1***********/                        private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
    }                                           
   /**********确定按钮调用NewClass类中的方法ee（）（该方法是打印输入框中的值）***********/ 
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        NewClass  s = new NewClass();
        s.ee();
                 
}
}   /**********一个新的类，它先通过getback（）方法获取上面输入框中的值，在打印***********/ 
public class NewClass {
    public void ee(){
    NewJFrame j = new NewJFrame();
    String k = j.getback();
    System.out.println(k);
       }
    
}问题是：jTextField1值不能及时的传送到Newclass类这边。
老兄，初学这玩意，标示鸭梨黑大啊。

Answer 15

public class NewJFrame extends javax.swing.JFrame {
    private String c;    public String getback()
    {
        return  this.c = jTextField1.getText();
    }                        
.......
.......
.......
.......
.......    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
    }                                               private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        NewClass s = new NewClass(this);//这里要有参数，不然找不到构造函数
        s.ee();
    }                                        .......
......
.....                   
}
public class NewClass {    private NewJFrame j;
    
    public NewClass(NewJFrame j)
    {
    this.j = j;
    }
    public void ee(){
    String k = j.getback();
    System.out.println(k);
    }
    
}或者这样也行public class NewJFrame extends javax.swing.JFrame {
    private String c;
    private NewClass s = new NewClass(this);//直接作为一个成员变量不用总new了    public String getback()
    {
        return  this.c = jTextField1.getText();
    }                        
.......
.......
.......
.......
.......    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
    }                                               private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        s.ee();
    }                                        .......
......
.....                   
}
public class NewClass {    private NewJFrame j;
    
    public NewClass(NewJFrame j)
    {
    this.j = j;
    }
    public void ee(){
    String k = j.getback();
    System.out.println(k);
    }
    
}

Answer 16

package socket;
public class NewJFrame extends javax.swing.JFrame {
    
private javax.swing.JButton jButton1;
    private javax.swing.JTextField jTextField1;
    /**
     * Creates new form NewJFrame
     */
    public javax.swing.JTextField getback()//注释过的改动了。其他无改动
    {
        return this.jTextField1;
    }    public NewJFrame(){
        initComponents();
    }
        private void initComponents() {        jTextField1 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);        jTextField1.setText("erg");
        jTextField1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField1ActionPerformed(evt);
            }
        });        jButton1.setText("jButton1");
        jButton1.addActionListener(new java.awt.event.ActionListener(){
            public void actionPerformed(java.awt.event.ActionEvent evt){
                jButton1ActionPerformed(evt);
            }
        });        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(156, 156, 156)
                        .addComponent(jButton1))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(108, 108, 108)
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 160, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(132, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(48, 48, 48)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(63, 63, 63)
                .addComponent(jButton1)
                .addContainerGap(145, Short.MAX_VALUE))
        );        pack();
    }                        private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt){
    
    }                                               private void jButton1ActionPerformed(java.awt.event.ActionEvent evt){                                         
        NewClass s = new NewClass(this);
        s.ee();//或者s.ee(this),这种就不写了，一般是上面那种写法。
    }
    
    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);
            }
        });
    }
}class NewClass {//如果你的NewClass 就这里用到了，直接写一个文件夹下就可以了。看个人爱好
private NewJFrame newJFrame = null;
    public NewClass(NewJFrame newJFrame){
     this.newJFrame = newJFrame;
    }
public void ee(){
    String k = newJFrame.getback().getText();
    System.out.println(k);
    }
}

Answer 17

不胜感激。问题已经解决。
public class NewClass {
    private NewJFrame j;//不过这里是什么意思呢没搞懂
    public NewClass(NewJFrame j) 
    { 
        this.j = j; 
    }
    public void ee()
    { 
        String k = j.getback(); 
        System.out.println(k); 
    }
}