FocusAdapter()

FocusListener flTextField = new FocusListener(){
	public void focusGained(FocusEvent ev){
		System.out.println("1");
	}
	public void focusLost(FocusEvent ev){
		System.out.println("2");
	}
};

tfMeuTextField.addFocusListener(flTextField);

FocusListener flTextField = new FocusListener(){
            public void focusGained(FocusEvent ev){
                    MaskFormatter formato = new MaskFormatter();
                try {
                    formato.setPlaceholderCharacter('_');
                    formato.setMask("##/##/####");
                    formato.install(textField);             
                }
                catch ( Exception ex ) {
                ex.printStackTrace();
                }
        
            }
            public void focusLost(FocusEvent ev){
 		
            }
        }; 
       textField.addFocusListener(flTextField);

MaskFormatter mfFormatoData = null;

try {

    mfFormatoData = new MaskFormatter("##/##/####");
    mfFormatoData.setPlaceholderCharacter('_');

} catch (java.text.ParseException e) {

    e.printStackTrace();

}

JFormattedTextField tfData = new JFormattedTextField(mfFormatoData);
panelCentral.add(tfData);