Hot cup of Java sir?

for (<start value>; <condition>; <increment>){
// code block
}

A for loop has a number of important features you need to know -
It will only loop if the condition returns true.
Whatever code is in the increment will be run at the end of the code block.
The curly brackets {} contain the code block to repeat.
Condition is tested BEFORE the code block is run. This means there is a chance the code block may never run.

for(int counter=0; counter < 5; counter = counter + 1){
System.out.println("Hello");
}

The above code will print out "hello" 5 times. The start value is 0 and the counter variable is called counter. In a loop we need to keep track of how many times the loop has err looped! This is so we can stop it! This is called the counter and it is nessesary to allow the condition to be satisfied. If the condition is NEVER satisfied then you get what is called a infinite loop. This will NEVER stop. For example -

for(int a=0; a<10; b = b + 1){

System.out.println("SPAMMMM!!!");

}

The above code will never stop. The reason for this is that "a" will never be above 10. The increment code, which gets run at the end of the code block, adds 1 to the varaible "b". As the condition is testing "a" we get an infinite loop.

int a= 0;
for(System.out.println("Start me"); a<4; System.out.println("Inc me " + a)){
System.out.println("hello");
a = a + 1;
}

The above code shows a Java quirk in that we can put ANY code in the start and incrment positions. You can be ever so clever about this if you want but it does show something very interesting. Look at the output of this code (yes it does compile and stop!).

Start me
hello
Inc me 1
hello
Inc me 2
hello
Inc me 3
hello
Inc me 4

Did you expect that? This is a great way of seeing the order of the for loop. So we do -

Run start value code
Test the condition if true continue otherwise stop
run code block
run increment code
jump back to 2

Notice that the increment happens AFTER the code block. The condition is run BEFORE the code block and we ALWAYS test the condition after the code block REGARDLESS.

next for loops and arrays >>

Basics