Java 如何在Swing中的JTextfield中设置类似占位符的文本
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How to set Text like Placeholder in JTextfield in swing
提问by Uday A. Navapara
I want to put some texts in text-Field when the form is load which instruct to user and when user click on that text-filed the texts remove automatically.
我想在加载表单时在 text-Field 中放置一些文本，以指示用户，当用户单击该文本文件时，文本会自动删除。
txtEmailId = new JTextField();
txtEmailId.setText("Email ID");
i have wrote above code but it display the text and keep as it is when user click on that text button i want to remove it.
我已经写了上面的代码，但它显示文本并在用户单击该文本按钮时保持原样，我想将其删除。
is there any way to do this task?
有什么办法可以完成这项任务吗？
采纳答案by MadProgrammer
I use to override the text fields paint method, until I ended up with more custom text fields then I really wanted...
我用来覆盖文本字段的绘制方法，直到我最终得到了更多的自定义文本字段，然后我才真正想要......
Then I found this prompt APIwhich is simple to use and doesn't require you to extend any components. It also has a nice "buddy" API
然后我发现了这个提示 API，它使用简单，不需要你扩展任何组件。它还有一个不错的“伙伴”API
This has now been included in the SwingLabs, SwingX librarywhich makes it even eaiser to use...
现在，它已包含在 SwingLabs、SwingX 库中，这使得它更易于使用...
For example (this uses SwingX-1.6.4)
例如（这里使用 SwingX-1.6.4）
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import org.jdesktop.swingx.prompt.PromptSupport;
public class PromptExample {
public static void main(String[] args) {
new PromptExample();
}
public PromptExample() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JTextField bunnies = new JTextField(10);
JTextField ponnies = new JTextField(10);
JTextField unicorns = new JTextField(10);
JTextField fairies = new JTextField(10);
PromptSupport.setPrompt("Bunnies", bunnies);
PromptSupport.setPrompt("Ponnies", ponnies);
PromptSupport.setPrompt("Unicorns", unicorns);
PromptSupport.setPrompt("Fairies", fairies);
PromptSupport.setFocusBehavior(PromptSupport.FocusBehavior.HIDE_PROMPT, bunnies);
PromptSupport.setFocusBehavior(PromptSupport.FocusBehavior.HIGHLIGHT_PROMPT, ponnies);
PromptSupport.setFocusBehavior(PromptSupport.FocusBehavior.SHOW_PROMPT, unicorns);
PromptSupport.setFontStyle(Font.BOLD, bunnies);
PromptSupport.setFontStyle(Font.ITALIC, ponnies);
PromptSupport.setFontStyle(Font.ITALIC | Font.BOLD, unicorns);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
frame.add(bunnies, gbc);
frame.add(ponnies, gbc);
frame.add(unicorns, gbc);
frame.add(fairies, gbc);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
回答by miguel angel
JTextField busqueda = new JTextField(20);
add(busqueda);
busqueda.setHorizontalAlignment(SwingConstants.CENTER);
if (busqueda.getText().length() == 0) {
busqueda.setText("Buscar");
busqueda.setForeground(new Color(150, 150, 150));
}
busqueda.addFocusListener(new FocusListener() {
@Override
public void focusGained(FocusEvent e) {
busqueda.setText("");
busqueda.setForeground(new Color(50, 50, 50));
}
@Override
public void focusLost(FocusEvent e) {
if (busqueda.getText().length() == 0) {
busqueda.setText("Buscar");
busqueda.setForeground(new Color(150, 150, 150));
}
}
});
回答by Uzziel Contreras
You can download this NetBeans pluginwhich you can use to create a placeholder with just one line.
您可以下载这个 NetBeans 插件，您可以使用它来创建仅一行的占位符。
