There are 3 types of loops:
while loop
do-while
for loop
while Loop
while(condition){ //execute some code } As long as the condition is true the code encapsulated in between brackets will keep executing
Example:
while(var_x<=10){ println(var_x) var_x++ }
Output is:
0
1
2
3
4
5
6
7
8
9
10
do – while loop
do{ //execute some code }while(condition)
The code in between brackets will execute at least one time and keep executing as long as the condition is true
int var_x = 80; do{ println(var_x); var_x++; }while(var_x<= 10);
Output of this is:
80
for loop
for(initialization; condition; increment){ //execute some code }
First we start from a value, that is the initialization, then a condition is placed, so code executes as long as the condition is true, then that value gets incremented.
Example:
for(int i = 0 ; i <=10; i++){ println(i) }
Output is:
0
1
2
3
4
5
6
7
8
9
10
When to use them.
Use while loop when you don’t know exactly how long you want some code to keep executing.
Use do-while, when you want your code to execute at least one time, regardless if the condition you place is true or false.So do-while is used when you want some code to be executed at least 1 time.
Use for loop when you know precisely how long you want to execute some code and from where to start.
Special case of for loop: for – each
for(vaiable : collection){ //code to execute }
– is used to make your code compact
– helps when you need to cycle through a collection of data
– also helps in reducing risk of programming errors
Example
int var_array = {1,2,3,4} for(int i: var_array){ println(i) }
The output of this code in run-time messages will be :
1
2
3
4
Infinite loop
An infinite loop is a cycle that never ends, so the environment will give you an error like
oracle.jbo.ExprTimeoutException Expression timed out.
Example of infinite loop:
def var_x = 80 while(var_x) { println(var_x) }