[英]DocumentFilter for negative and positive integer
我知道這是一個常見的問題,但我正在嘗試創建一個只接受int數字的TextField,它幾乎完成了,這里是代碼:
創建文本字段:
nome = new JFormattedTextField();
nome.setHorizontalAlignment(SwingConstants.CENTER);
nome.setColumns(2);
DocumentFilter filtro = new FiltroNumero();
((AbstractDocument) nome.getDocument()).setDocumentFilter(filtro);
panel.add(nome);
DocummentFilter:
public class FiltroNumero extends DocumentFilter{
public void insertString(DocumentFilter.FilterBypass fb, int offset, int length,
String text, javax.swing.text.AttributeSet attr)
throws BadLocationException {
fb.insertString(offset, text.replaceAll("[^-0-9]", ""), attr);
}
}
有了這個,TextField只接受數字和“ - ”,但這意味着“1-”是一個可能的值。
我需要的是一種方法,使文本字段不接受第一個字符后的減號。
如果有人可以幫助我,我會很高興:)
您可以簡單地從Document
(這是替換之前)獲取整個文本,然后從該文檔文本創建一個新的String,添加text
參數。 然后檢查一個匹配整數(負數或正數)的完整正則表達式。 如果匹配,則執行替換。 就像是:
@Override
public void replace(FilterBypass fb, int offs, int length,
String str, AttributeSet a) throws BadLocationException {
String text = fb.getDocument().getText(0,
fb.getDocument().getLength());
StringBuilder builder = new StringBuilder(text);
builder.insert(offs, str);
String newText = builder.toString();
// check
System.out.println("text = " + text
+ ", offset = " + offs
+ ", newText = " + newText);
if (newText.matches("(-)?\\d*")) {
super.replace(fb, offs, length, str, a);
} else {
Toolkit.getDefaultToolkit().beep();
}
}
注意:你應該使用replace
而不是insertString
,盡管不會因為覆蓋它們而受到傷害。
這是一個完整的演示
import java.awt.Toolkit;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
public class FilterDemo {
public FilterDemo() {
JFrame frame = new JFrame();
frame.add(createFilteredField());
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JTextField createFilteredField() {
JTextField field = new JTextField(10);
AbstractDocument document = (AbstractDocument) field.getDocument();
document.setDocumentFilter(new DocumentFilter() {
@Override
public void replace(FilterBypass fb, int offs, int length,
String str, AttributeSet a) throws BadLocationException {
String text = fb.getDocument().getText(0,
fb.getDocument().getLength());
StringBuilder builder = new StringBuilder(text);
builder.insert(offs, str);
String newText = builder.toString();
// check
System.out.println("text = " + text
+ ", offset = " + offs
+ ", newText = " + newText);
if (newText.matches("(-)?\\d*")) {
super.replace(fb, offs, length, str, a);
} else {
Toolkit.getDefaultToolkit().beep();
}
}
@Override
public void insertString(FilterBypass fb, int offs, String str,
AttributeSet a) throws BadLocationException {
String text = fb.getDocument().getText(0,
fb.getDocument().getLength());
StringBuilder builder = new StringBuilder(text);
builder.insert(offs, str);
String newText = builder.toString();
// checks
System.out.println("text = " + text
+ ", offset = " + offs
+ ", newText = " + newText);
if (newText.matches("(-)?\\d*")) {
super.insertString(fb, offs, str, a);
} else {
Toolkit.getDefaultToolkit().beep();
}
}
});
return field;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new FilterDemo();
}
});
}
}
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