Java Loop Structures - datacouch-io/spark-java GitHub Wiki

1. While Loop

The while loop iterates through a code block as long as a specified condition remains true:

Syntax for While Loop:

while (condition) {
  // Code block to be executed
}

Example:

int i = 0;
while (i < 5) {
  System.out.println(i);
  i++;
}

The Do/While Loop

The do/while loop is a variation of the while loop. It executes the code block once before checking the condition. If the condition is true, it continues to execute the loop.

Syntax for Do/While Loop:

do {
  // Code block to be executed
} while (condition);

This loop always executes at least once, even if the condition is initially false.

Example:

int i = 0;
do {
  System.out.println(i);
  i++;
} while (i < 5);

2. For Loop

The for loop is used to iterate through a code block a specific number of times.

Syntax for For Loop:

for (initialization; condition; update) {
  // Code block to be executed
}

• Initialization: Executed once before entering the loop.
• Condition: Checked before each iteration; if true, the loop continues.
• Update: Executed after each iteration.

Example:

for (int i = 0; i < 5; i++) {
  System.out.println(i);
}

For-Each Loop

The "for-each" loop is designed specifically for iterating through elements in an array or collection.

Syntax for For-Each Loop:

for (type variable : arrayname) {
  // Code block to be executed
}

Example:

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
for (String car : cars) {
  System.out.println(car);
}

These loop structures provide versatile ways to control the flow of your Java programs, allowing you to execute code repeatedly based on specific conditions or for a predetermined number of iterations.