Java Textfield重点

Question

你好，我的重点有问题

mytext= new JTextField();
mytext.requestFocus(true);
gc.fill =GridBagConstraints.HORIZONTAL ;
gc.gridx =3; gc.gridy=4;
gbl.setConstraints(mytext,gc);
jContentPane.add(mytext);

我试过了

mytext.requestFocus();

太

以及如何在文本字段中自动选择文本以标记文本？

Answer 1

从Swing教程

如果要确保特定组件在第一次激活窗口时获得焦点，则可以在实现组件之后但在显示框架之前调用组件上的requestFocusInWindow方法。以下示例代码显示了如何完成此操作：

//...Where initialization occurs...
JFrame frame = new JFrame("Test");
JPanel panel = new JPanel(new BorderLayout());

//...Create a variety of components here...

//Create the component that will have the initial focus.
JButton button = new JButton("I am first");
panel.add(button);
frame.getContentPane().add(panel);  //Add it to the panel

frame.pack();  //Realize the components.
//This button will have the initial focus.
button.requestFocusInWindow(); 
frame.setVisible(true); //Display the window.