The for and while loop in java

We often arrive in this situation when we need to unwind a block of instructions several times. Java provides three types of loops:
  • for loop
  • while loop
  • do loop. while

The for loop in java

The for loop allows statements to be executed inside the block in repetition a certain number of times. It is useful when you know how many times the task will be repeated.
The syntax is as follows:

for(initialization, expression, increment)
  • Initialization initializes the loop, .
  • The loop stops when the expression condition is false.
  • The variable increments or decrements after each execution.
Example:

for(int i = 0 ; i < 10 ; i++)
 System.out.println(i);
Output:

0
1
2
3
4
5
6
7
8
9
The three for expressions are optional, An infinite loop is created as follows:

for( ; ; ) 
 //instructions

The foreach loop in java

Another loop called the advanced for loop(Enhanced for  ) designed for table browsing and data collections such as ArrayList. The following program implements the advanced for loop to iterate through array:

String[] t = {"a","b","c","d","e","f","g","h","i","j","k"}; 
for(String s:t)
 System.out.println(s);
Output:

a
b
c
d
e
f
g
h
i
j
k

The while loop in java
The while loop executes the block as long as the condition is true. Its syntax is as follows:

while(expression)
 //instructions
The condition of the expression evaluates and returns a Boolean value. If it is true, the while loop executes the block and continues execution until the expression evaluation returns a value false.

Example:

int nb=8; 
while(nb> 0)
 System.out.println(nb--);
Result:
8
7
6
5
4
3
2
1

The do-while loop in java

The do-while loop is similar to while except that do-while checks the condition at the end of the loop, so the block is executed at least once as shown in its syntax:

do {
 //bloc
}while(expression);

Example:

nb=1; 
do{
 System.out.println(nb++); 
}while(nb%10!=0);
Output:
1
2
3
4
5
6
7
8
9
References:
Java: Loops and conditional structures
oracle: The for Statement
oracle : The while Statement