🚀 go-pugleaf

On Sat, 23 Sep 2000 22:22:14 -0400, Scott Howes wrote:

>     if (jTextField1 = " ")
>     jTextField1.setText("Add Text");  // incompatible types
> 
>     if (jTextField1.getText() = "")
>     jTextField1.setText("Add Text");  // variable required but found

In Java (and C/C++), the "=" operator performs an assignment, not an 
equality comparison.  This is the equivalent of the Pascal ":=" operator.  
The "==" operator is the equivalent of the Pascal "=".
But in Java, there is another twist.  The "==" operator compares the 
identity of two object references.  It will return true if the variables 
refer to the exact same object, not just two objects with the same value.  
So it is quite possible for two string variables to refer to the same 
string value, but not compare as equal using the "==".

The equals() method compares object values, which is what you want.  So 
instead of the above code, what you probably want:

    if ( jTextField1.getText().equals("") ) ...

or perhaps:

    if ( jTextField1.getText().length() == 0 ) ...

You also might want to check whether the field contains only blanks, 
rather than just whether it is empty.  If a user hits the space bar in 
the field, it will not be apparent that the field contains a blank, and 
the different behavior would be confusing.  I have a string utility class 
that has methods for performing tests like this, so I would write:

    if ( StringUtil.isBlank( jTextField1.getText() ) ) ...

-- 
Regards,

John McGrath

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