Introduction to Control Structures in Java

Control structures are fundamental programming constructs that determine the flow and decision-making in a program. They enable you to control the sequence, repetition, and selection of code execution, allowing for dynamic and flexible behavior. In Java, control structures can be categorized into three primary types: conditional, looping, and branching.

1. Conditional Control Structures

Conditional control structures allow programs to execute certain code blocks only if specific conditions are met. The main conditional statements in Java are:

• if Statement: Executes a block of code if a condition is true.
• else Statement: Provides an alternative block to execute if the if condition is false.
• else if Ladder: Allows multiple conditions to be checked sequentially.
• switch Statement: Evaluates a single expression against multiple possible values, executing the corresponding code block. Useful for cases where many conditions depend on the same variable.

Example:

int num = 5;
if (num > 0) {
    System.out.println("Positive number");
} else if (num < 0) {
    System.out.println("Negative number");
} else {
    System.out.println("Zero");
}

2. Looping Control Structures

Looping structures repeat a block of code multiple times, either for a specified number of iterations or while a condition remains true. Java provides several types of loops:

• for Loop: Iterates a block of code a set number of times.
• while Loop: Repeats the code as long as a condition is true.
• do-while Loop: Similar to while, but guarantees that the loop executes at least once, as the condition is checked after the loop body.

Example:

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

3. Branching Control Structures

Branching controls allow for changes in the normal flow of execution by breaking out of loops or skipping iterations. Java’s primary branching statements are:

• break: Exits a loop or switch statement prematurely.
• continue: Skips the current iteration in a loop and proceeds to the next iteration.
• return: Exits a method and optionally returns a value.

Example:

for (int i = 0; i < 5; i++) {
    if (i == 3) {
        continue; // Skips iteration when i is 3
    }
    System.out.println("Value: " + i);
}

Summary

Control structures are essential for building logic and controlling the program’s flow, allowing Java applications to make decisions, iterate, and respond to various inputs and conditions.