Java 限制 TextField 输入
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Limiting TextField inputs
提问by user3260589
I'm trying to make a textfield that limits a user input. I have this code:
我正在尝试制作一个限制用户输入的文本字段。我有这个代码：
private void jTextField5KeyTyped(java.awt.event.KeyEvent evt) {
//This limits the input:
if(jTextField5.getText().length()>=2) {
jTextField5.setText(jTextField5.getText().substring(0, 1));
}
}
It successfully limits the input. However, when I tried to press other characters on the keyboard, it changes the last character on the textfield. Any ideas to stop this? I know others will say that I should use Document(Can't remember) in making this kind of stuff, but I can't. I don't know how to do it in netbeans. Please help.
它成功地限制了输入。但是，当我尝试按键盘上的其他字符时，它会更改文本字段上的最后一个字符。有什么想法可以阻止这种情况吗？我知道其他人会说我应该使用 Document（不记得）来制作这种东西，但我不能。我不知道如何在 netbeans 中做到这一点。请帮忙。
采纳答案by A-SM
Here's a simple way to do it:
这是一个简单的方法：
private void textFieldKeyTyped(java.awt.event.KeyEvent evt) {
if(textField.getText().length()>=2) {
evt.consume();
}
}
回答by Alya'a Gamal
Try this Example which Use PlainDocument:
试试这个使用PlainDocument 的例子：
class JTextFieldLimit extends PlainDocument {
private int limit;
JTextFieldLimit(int limit) {
super();
this.limit = limit;
}
JTextFieldLimit(int limit, boolean upper) {
super();
this.limit = limit;
}
public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException {
if (str == null) {
return;
}
if ((getLength() + str.length()) <= limit) {
super.insertString(offset, str, attr);
}
}
}
public class Main extends JFrame {
JTextField textfield1;
JLabel label1;
public void init() {
setLayout(new FlowLayout());
label1 = new JLabel("max 10 chars");
textfield1 = new JTextField(10);
add(label1);
add(textfield1);
textfield1.setDocument(new JTextFieldLimit(110));///enter here the Maximum input length you want
setSize(300, 300);
setVisible(true);
}
}
