Swing: the initial String of JTextField is an empty String

Question

About the constructor of JTextField, the javadoc says:

public JTextField()

Constructs a new TextField. A default model is created, the initial string is null, and the number of columns is set to 0.

But when I use this constructor, the method getText() of JTextField returns an empty String, for example:

boolean b = new JTextField().getText().isEmpty();  // returns true.

Why the value returned by getText() is an empty String instead of null?

score 7 · Accepted Answer · answered Aug 29 '16 at 11:58

JTextField get the text from the Document , default implementation PlainDocument never returns null. even though you tried to call JTextField.setText(null), it will just clear the value of the Document content, but still getText will return empty string.

Swing: the initial String of JTextField is an empty String

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