If statement doesn't work in JPanel

Question

Hi everybody.
I'd like somebody tell me the reason why the "if" statement doesn't work in a Jpanel but works in a Japplet. I'm including the fragments of code that are relevant to the question.
Thanks in advance.
public class Applet_INVEN extends JApplet {
jTabbedPane jTabbedPane1 = new JTabbedPane();
Panel_1 p_1 = new Panel_1();
JLabel jLabel1 = new JLabel();
JTextField jTextField1 = new JTextField();
JButton jButton1 = new JButton();
void jButton1_actionPerformed(ActionEvent e) {
if (jTextField1.getText() != "0") //------Executes when the condition is true
jLabel1.setText("bingo");
public class Panel_1 extends JPanel {//------INSIDE a JPANEL
JTextField jTextField1 = new JTextField();
JTextField jTextField2 = new JTextField();
JTextField jTextField3 = new JTextField();
JButton jButton1 = new JButton();
void jButton1_actionPerformed(ActionEvent e) {
jTextField2.setText(jTextField1.getText()); //----Ever executes, of course!
if(jTextField1.getText() != "0") //----Never executes, even when
jTextField3.setText("ojo"); //----the condition is true!

Answer 1

You shouldn't use the != operator to test equality of Objects. Use Object.equals() instead.
if (jTextField1.getText() != "0")
should be
if ( ! jTextField1.getText().equals("0"))
or better:
if ( ! "0".equals(jTextField1.getText())) <-- avoids null pointer exception.