Re-Using Objects

Question

Could someone explain if re-using the same object to create multiple instances of the object (say a JTextField) is better than defining a whole new object for each instance.JTextField tf;
public void createFields() {
  tf = new JTextField(20);
  tf.setBackground(Color.green);
  JPanel p = new JPanel();
   p.add(tf);
  tf = new JTextField(20);
  tf.setBackground(Color.red);
  p.add(tf);
  contentPane.add(p, BorderLayout.CENTER ); // Just for explanation purposes.
} Is this a better way to do things. as against JTextField tf, tf2;
public void createFields() {
  tf = new JTextField(20);
  tf.setBackground(Color.green);
  JPanel p = new JPanel();
   p.add(tf);
  tf2 = new JTextField(20);
  tf2.setBackground(Color.red);
  p.add(tf2);
  contentPane.add(p, BorderLayout.CENTER ); // Just for explanation purposes.
} I ask because,
1. how will you be able to identify a particular field when you need to get some piece of information?
2. Is this is a better way to utilize system resources?
ICE

Answer 1

By the way I have another question.
Imports
It is advisable to be importing whole packages instead
of specific classes. I ask because I tend to do
this.import javax.swing.border.*;when in the whole class I might just use the
LineBorder or EmptyBorder. Does this also have some
effect on performance in terms of initial start up of
my application.?
ICENo, java only includes those classes which are necessary, doesn't make any difference in application. May be importing whole packages might slow down the compile time, nothing more than that.