Some useful classes - Multimedia Introduction to Programming Using Java - page 198

The assignment gets the values of the first two int fields and stores their sum in
sum . Here, you can see that the following expression has as its value the integer
that is in int field i (for i in the range 0..6 —the first field is numbered 0 ):
getIntField(i)
In the same way, it is easy to store a value in a field. The second statement,
setIntField(2,sum);
stores in int field 2 the value that is in variable sum . In general, the statement
setIntField(i,e);
stores the value of expression e in int field i , where expression i is in 0..6 .
Methods also exist for accessing and changing the double and String fields:
getdoubleField(i)
getStringField(i)
setDoubleField(i,e);
setStringField(i,e);
Executing the GUI
Execution of the following call creates and shows the GUI window.
Thereafter, you can drag the window where you want, resize it, and use the fields
and ready button.
MyJLiveWindow.main( null );
An example
Consider the following method:
/** = the number of seconds n , but given in the form
hours:minutes:seconds . Precondition: n>=0 */
public static String convert( int n) {
int hours= n / 3600;
int remainder= n % 3600;
return hours + ":" + (remainder / 60) +
":" + (remainder % 60);
}
To test this method, place it in class MyJLiveWindow , change it so that it has one
int field and one String field, and write method buttonPressed as follows:
/** D isplay value convert(first int field) in the first string field */
public Object buttonPressed() {
setStringField(0, convert(getIntField(0)));
return null ;
}