Java Series for Beginners: Loops

Introduction to Loops

• Loops make Java dynamic by allowing code to repeat.
• Different actions can be performed on each iteration.

Types of Loops in Java

1. While Loop

• Syntax: Similar to the if statement.

  while (condition) {
      // code to be repeated
  }
  

• Functionality:
  • Uses a boolean condition.
  • Repeats the code block as long as the condition is true.
  • Example: Infinite loop using while (true).
  • Practical example: Incrementing a variable until it reaches a value.

Example:

int a = 0;
while (a < 100) {
    System.out.println(a);
    a++;
}
System.out.println("Loop finished");

• Prints numbers from 0 to 99 and then outputs "Loop finished".

2. For Loop

• Syntax:
  • Takes three parameters: initialization, condition, and increment/decrement.

  for (initialization; condition; increment/decrement) {
      // code to be executed
  }
  

• Functionality:
  • Initializes a variable, checks a condition, and increments/decrements in one line.
  • Useful for iterating over arrays.

Example:

for (int a = 0; a < 100; a++) {
    System.out.println(a);
}

• Prints numbers from 0 to 99.
• Increment can use a += 2 to skip numbers.

3. Do-While Loop

• Syntax:

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

• Functionality:
  • Ensures the code inside runs at least once, regardless of the condition.
  • Condition is checked after the code runs.

Example:

int a = 10;
do {
    System.out.println("Hello World");
} while (a < 10);

• Prints "Hello World" once even if the condition a < 10 is false.

Summary

• While Loop: Repeats as long as the condition is true, checks condition first.
• For Loop: Combines initialization, condition, and increment in one line.
• Do-While Loop: Executes code at least once before checking the condition.

Understanding these loops allows for creating dynamic and flexible Java programs.