Loop Instructions

Java has three main types of loops:

Loop Type	Use Case
for	Known number of repetitions
while	Unknown repetitions, check before each iteration
do-while	Similar to while, but always runs at least once

1. For Loop

• Syntax:

  for (initialization; condition; update) {
    // code block
  }
  

• Example:

  for (int i = 1; i <= 5; i++) {
    System.out.println("Count: " + i);
  }
  

• Flow:
  1. Initialize i = 1
  2. Check condition i <= 5
  3. Execute code
  4. Update i++
  5. Repeat step 2.

2. While Loop

• Syntax:

  while (condition) {
    // code block
  }
  

• Example:

  int i = 1;
  while (i <= 5) {
    System.out.println("Count: " + i);
    i++;
  }
  

• Flow:
  1. Check condition.
  2. If true, run the block and repeat step 1.
  3. Else, end process.

3. Do-while Loop

• Syntax:

  do {
    // code block
  } while (condition);
  

• Example:

  int i = 1;
  do {
    System.out.println("Count: " + i);
    i++;
  } while (i <= 5);
  

• Flow:
  1. Run the block once
  2. Check the condition.
  3. If true, run the block and repeat step 2.
  4. Else, end process.

4. Loop Control: break and continue

• break: exit the loop early.

• continue: skip the current iteration.

• Example:

  for (int i = 1; i <= 5; i++) {
    if (i == 3) continue;  // skip 3
    if (i == 5) break;     // stop at 4
    System.out.println(i);
  }
  

  Code Demo

  public class LoopExamples {
    public static void main(String[] args) {
        // for loop
        for (int i = 0; i < 3; i++) {
            System.out.println("for loop: " + i);
        }
  
        // while loop
        int j = 0;
        while (j < 3) {
            System.out.println("while loop: " + j);
            j++;
        }
  
        // do-while loop
        int k = 0;
        do {
            System.out.println("do-while loop: " + k);
            k++;
        } while (k < 3);
    }
  }
  

  Output:

  for loop: 0
  for loop: 1
  for loop: 2
  while loop: 0
  while loop: 1
  while loop: 2
  do-while loop: 0
  do-while loop: 1
  do-while loop: 2