JTextFiledは数字と長さの制限のみ入力

public class MyJTextField extends JTextField {
    private int limit = Integer.MAX_VALUE;
    private boolean numberOnly;

    public MyJTextField() {
        addKeyListener(new KeyAdapter() {
            @Override
            public void keyTyped(KeyEvent e) {
                if (getText().length() + 1 > limit) {
                    deleteInputChar(e);
                    return;
                }
                if (numberOnly) {
                    char input = e.getKeyChar();
                    if (!Character.isDigit(input)) {
                        deleteInputChar(e);
                    }
                }
            }

            private void deleteInputChar(KeyEvent source) {
                source.setKeyChar((char) KeyEvent.VK_CLEAR);
            }
        });

    }

    public void setMaxTextLength(int limit) {
        if (limit < 0) {
            return;
        }
        this.limit = limit;
    }

    public int getMaxTextLength() {
        return limit;
    }

    public void setNumberOnly(boolean numberOnly) {
        this.numberOnly = numberOnly;
    }

    public boolean isNumberOnly() {
        return this.numberOnly;
    }
}