使用方法添加JTextField时从JTextField检索文本

Question

我目前正在学习如何在Java中使用Swing。 当向JPanel添加JTextFields，JLabels或JButtons时，我通常在以下4行中这样做：

gbc.gridx = 0;
gbc.gridy = 0;
JTextField example = new JTextField("", 6);
p.add(example, gbc);

但是我试图通过制作这样的方法来压缩我的代码：

public static void addTextField (JPanel p, GridBagConstraints gbc, String str, int x, int y, int len) {
gbc.gridx = x;
gbc.gridy = y;
JTextField tempTF = new JTextField(str, len);
p.add(tempTF, gbc);
}

并在主要方法中调用addTextField（），例如：

ClassName.addTextField(p2, gbc, "", 1, 1, 6);

我的问题是如何在JTextField中检索文本。 就像是，

String str = example.getText();

要么

String str2 = tempTF.getText();

通常可以正常工作，现在不再有效。

关于如何解决这个问题有什么想法吗？

这是我正在使用的完整代码，之前没有任何答案：

/**
* This program creates two windows.
* Window #1 displays Hello World
* WIndow #2 prompts users to input information
*/

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class MessingWithSwing extends JFrame{

  //Main Method
  public static void main(String[] args) { 
    //makes the first window
    MessingWithSwing window1 = new MessingWithSwing("Window #1", 300, 300);
    //makes the second window with minimum dimensions
    MessingWithSwing window2 = new MessingWithSwing("Window #2", 450, 300, 300, 300);

    //GridBagConstraints allows the objects in each panel to be positioned in grid cordinates
    GridBagConstraints gbc = new GridBagConstraints();
    //sets the spaces between each grid position
    gbc.insets = new Insets(10, 10, 10, 10);

    //creates a JPanel that uses a grid layout
    JPanel p1 = new JPanel(new GridBagLayout());
    //adds the panel in the center of window1
    window1.add(p1, BorderLayout.CENTER);
    //sets the panel visible so it can correctly display the labels, textfields, and buttons
    p1.setVisible(false);

    //uses the method created below to add JLabels to p1
    MessingWithSwing.addLabel(p1, gbc, "Hello", 0, 0);
    MessingWithSwing.addLabel(p1, gbc, "World", 0, 1);

    p1.setVisible(true);

    //creates a second JPanel that also uses a grid layout
    JPanel p2 = new JPanel(new GridBagLayout());
    //adds the panel at the top of window2
    window2.add(p2, BorderLayout.NORTH);
    //sets the panel visible so it can correctly display the labels, textfields, and buttons
    p2.setVisible(false);

    //uses the method created below to add JLabels to p2
    MessingWithSwing.addLabel(p2, gbc, "Please Enter The Following", 0, 0);
    MessingWithSwing.addLabel(p2, gbc, "Name: ", 0, 1);
    MessingWithSwing.addLabel(p2, gbc, "Age: ", 0, 2);

    //uses the method created below to add JTextFields to p2
    MessingWithSwing.addTextField(p2, gbc, "", 1, 1, 6);
    MessingWithSwing.addTextField(p2, gbc, "<age>", 1, 2, 6);

    //uses the method created below to add a JButton to p2
    MessingWithSwing.addButton(p2, gbc, "Enter", 0, 3);

    p2.setVisible(true);

    /* Issue:
     * The someting like the line below would not work
     * How would you access the text inputted into each JTextField?
     */
//    String str = tempTF.getText();

  } //end of Main Method

  //first constructor makes a window that is completely resizable
  public MessingWithSwing(String title, int sizeX, int sizeY) {
    super(title);
    setSize(sizeX, sizeY);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);
  }

  //second constructor makes a window that is resizable but has minimum dimensions
  public MessingWithSwing(String title, int sizeX, int sizeY, int minSizeX, int minSizeY) { 
    super(title);
    setSize(sizeX, sizeY);
    setMinimumSize(new Dimension(minSizeX, minSizeY));
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);
  }

  //This method adds a JLabel with an indicated text, at an indicated GridBagConstraints location, to an indicated JPanel
  public static void addLabel(JPanel p, GridBagConstraints gbc, String str, int x, int y) {
    gbc.gridx = x;
    gbc.gridy = y;
    JLabel tempLabel = new JLabel(str);
    p.add(tempLabel, gbc);
  }

  //This method adds a JTextField with an indicated length and text, at an indicated GridBagConstraints location, to an indicated JPanel
  public static void addTextField (JPanel p, GridBagConstraints gbc, String str, int x, int y, int len) {
    gbc.gridx = x;
    gbc.gridy = y;
    JTextField tempTF = new JTextField(str, len);
    p.add(tempTF, gbc);
  }

  //This method adds a JButton with an indicated text, at an indicated GridBagConstraints location, to an indicated JPanel
  public static void addButton (JPanel p, GridBagConstraints gbc, String str, int x, int y) {
    gbc.gridx = x;
    gbc.gridy = y;
    JButton tempB = new JButton(str);
    p.add(tempB, gbc);
  }

}

因此，如果我正确理解Kequiang Li，它的外观将类似于：

public static JTextField addTextField (JPanel p, GridBagConstraints gbc, String str, int x, int y, int len) {
    gbc.gridx = x;
    gbc.gridy = y;
    JTextField tempTF = new JTextField(str, len);
    p.add(tempTF, gbc);
    return tempTF;
  }

然后：

ArrayList<JTextField> tfList = new ArrayList<JTextField>();
tfList.add(ClassName.addTextField(p1,gbc,text,0,0,8));
String str = tfList.get(0).getText();

Answer 1

如何在文本字段中获取文本完全取决于要在何时何地获取文本。

假设您想随时检索文本，然后可以使addTextField返回它已添加的文本字段。 这样，您可以跟踪列表，数组甚至是映射中的所有文本字段，而只需在这些文本字段上调用getText 。

在另一种情况下，您可能仅在用户在文本字段中按下Enter键时才需要文本，然后可以将侦听器绑定到文本字段。 事件发生时，您可以访问事件的源（即文本字段），然后检索文本。