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import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
public class Main{
public static void main(String[] args) {
DocumentFilter dfilter = new UpperCaseFilter();
JTextArea jta = new JTextArea();
((AbstractDocument) jta.getDocument()).setDocumentFilter(dfilter);
JFrame frame = new JFrame("UpcaseFilter");
frame.getContentPane().add(jta, java.awt.BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(200, 120);
frame.setVisible(true);
}
}
class UpperCaseFilter extends DocumentFilter {
public void insertString(DocumentFilter.FilterBypass fb, int offset, String text,
AttributeSet attr) throws BadLocationException {
fb.insertString(offset, text.toUpperCase(), attr);
}
public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text,
AttributeSet attr) throws BadLocationException {
fb.replace(offset, length, text.toUpperCase(), attr);
}
}
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