while
statement is to repeat
something many times.
while
statement has this form:
while (condition) { statements to repeat while the condition is true }
true
or false
true
or false
(ie, a boolean
value). It is often a comparison (see example below).
public void paintComponent(Graphics g) { super.paintComponent(g); int count = 0; while (count < 50) { g.drawLine(20, count*5, 80, count*5); count = count + 1; } g.drawString("Loop is finished. count="+count, 10, 300); }//end paintComponentThis repeats the drawLine() call 50 times. The first time the while condition is tested, it is
true
because
the value of count
is 0, which is less than 50.
After the statements in the body are done, the while loop comes
back to the top of the loop and makes the test again.
Each time the value of count
is larger.
Finally, count
is 50, and the value of the condition will be false.
When the loop stops, the program continues with the statement after
the end of the loop (the drawLine() call). This will display
the string "Loop is finished. count=50
".