Loop Statements

In programming, sometimes there is need to execute the block of code repeatedly while some condition evaluates to true. The execution of the set of instructions depends upon a particular condition.

In Java, there are three types of loops. 

1. for loop
2. for each loop
3. while loop
4. do-while loop

for loop:

In Java, for loop is similar to C and C++. It enables us to initialize the loop variable, check the condition, and increment/decrement in a single line of code.

For loop is used only when we exactly know the number of times, we want to execute the block of code.

syntax:

for(initialization, condition, increment/decrement) {    

//block of statements    

}   

for-each loop:

Java provides an enhanced for loop to traverse the data structures like array or collection. In the for-each loop, there is no need to update the loop variable.

The syntax to use the for-each loop in java is given below:

for(data_type var : array_name/collection_name){    

//statements    

}    

while loop:

The while loop is also used to iterate over the number of statements multiple times.

Unlike for loop, the initialization and increment/decrement doesn't take place inside the loop statement in while loop. It is also known as the entry-controlled loop since the condition is checked at the start of the loop. If the condition is true, then the loop body will be executed; otherwise, the statements after the loop will be executed.

syntax:

while(condition){    

//looping statements    

}  

do-while loop:

The do-while loop checks the condition at the end of the loop after executing the loop statements. It is also known as the exit-controlled loop since the condition is not checked in advance.

syntax:

do     

{    

//statements    

} while (condition);