Java Language - 5 - Control Flow (if, else, switch, loops)

Java Fundamentals – Control Flow (if, else, switch, loops)

Introduction

Control flow structures are essential in Java to make decisions, control the flow of a program, and execute code repeatedly. In this guide, we’ll explore the use of control flow constructs such as ‘if’ statements, ‘else’ clauses, ‘switch’ statements, and various loops.

Conditional Statements with ‘if’ and ‘else’

The ‘if’ statement is used for conditional execution, allowing you to run code only when a specified condition is true. You can also use ‘else’ to execute alternative code when the condition is false.


int age = 25;

if (age >= 18) {
    System.out.println("You are an adult.");
} else {
    System.out.println("You are not yet an adult.");
}

‘if’ and ‘else’ statements help make decisions in your Java programs based on certain conditions.

‘switch’ Statement for Multiple Choices

The ‘switch’ statement is useful when you have multiple options to choose from based on the value of an expression. It provides a clean way to write branching logic.


int day = 3;
String dayName;

switch (day) {
    case 1:
        dayName = "Monday";
        break;
    case 2:
        dayName = "Tuesday";
        break;
    case 3:
        dayName = "Wednesday";
        break;
    // Handle more cases as needed
    default:
        dayName = "Unknown";
        break;
}

System.out.println("Today is " + dayName);

The ‘switch’ statement simplifies choosing between multiple options based on the value of an expression.

‘for’ Loop for Repetitive Tasks

The ‘for’ loop is ideal for executing a block of code a specified number of times. It provides precise control over loop initialization, condition, and iteration.


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

‘for’ loops are commonly used when you know how many times you need to repeat a task.

‘while’ Loop for Indefinite Repetition

The ‘while’ loop is used when you want to execute a block of code as long as a specified condition is true. It’s ideal for tasks with an unknown number of iterations.


int count = 0;
while (count < 5) {
    System.out.println("Count: " + count);
    count++;
}

‘while’ loops are useful when you need to repeat a task as long as a certain condition holds.

‘do-while’ Loop for Ensuring at Least One Execution

The ‘do-while’ loop is similar to the ‘while’ loop, but it guarantees that the block of code is executed at least once before checking the condition.


int num = 0;
do {
    System.out.println("Number: " + num);
    num++;
} while (num < 3);

‘do-while’ loops are useful when you want to execute a block of code at least once and then repeat it based on a condition.

Nested Control Flow

Java allows you to nest control flow structures, enabling you to create complex logic and handle a variety of scenarios.


int x = 10;
int y = 5;

if (x > 5) {
    if (y < 8) {
        System.out.println("Both conditions are true.");
    } else {
        System.out.println("First condition is true, but not the second.");
    }
} else {
    System.out.println("First condition is false.");
}

Nested control flow can be used to manage intricate situations where multiple conditions need to be checked.

Conclusion

Control flow structures are indispensable in Java programming for decision-making and loop control. By understanding how ‘if’ and ‘else’ statements, ‘switch’ statements, and various loops work, you gain the ability to create dynamic and efficient programs to meet your specific requirements.

Java Language – 5 – Control Flow (if, else, switch, loops)