Introduction

In the previous lesson, we explored expressions in Java and how they form the foundation for evaluating and processing data. Now, we move on to control flow statements, which allow developers to dictate the execution path of a program based on conditions and loops. Java provides several control flow statements, including decision-making statements, looping statements, and branching statements.

Decision-Making Statements

These statements allow a program to execute specific code based on given conditions.

if Statement

The if statement executes a block of code only if a specified condition evaluates to true.

int num = 10;

if (num > 0) {
    System.out.println("Positive number");
}

/**
* Output:
* Positive number
*/

if-else Statement

The if-else statement provides an alternative execution path when the condition evaluates to false.

int num = -5;

if (num > 0) {
    System.out.println("Positive number");
} else {
    System.out.println("Non-positive number");
}

/**
* Output:
* Non-positive number
*/

if-else-if Ladder

The if-else-if-ladder is used when multiple conditions need to be checked sequentially.

int num = 0;

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

/**
* Output:
* Zero
*/

switch Statement

The switch statement simplifies multiple if-else-if conditions when comparing a variable against multiple values.

int day = 3;

switch (day) {
    case 1: System.out.println("Monday"); break;
    case 2: System.out.println("Tuesday"); break;
    case 3: System.out.println("Wednesday"); break;
    default: System.out.println("Invalid day");
}

/**
* Output:
* Wednesday
*/

Looping Statements

Loops execute a block of code multiple times until a condition is met.

for Loop

Executes a block of code for a fixed number of iterations.

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

/**
* Output
* Iteration: 1
* Iteration: 2
* Iteration: 3
* Iteration: 4
* Iteration: 5
*/

while Loop

Repeats execution while a condition remains true.

int i = 1;

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

/**
* Output
* Iteration: 1
* Iteration: 2
* Iteration: 3
* Iteration: 4
* Iteration: 5
*/

do-while Loop

Executes the loop body at least once, even if the condition is false.

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

/**
* Output
* Iteration: 1
* Iteration: 2
* Iteration: 3
* Iteration: 4
* Iteration: 5
*/

Branching Statements

Branching statements alter the normal flow of loops and switch statements. They are also known as Jump Statements.

break Statement

Exits a loop or switch statement immediately.

for (int i = 1; i <= 5; i++) {
    if (i == 3) {
        break;
    }

    System.out.println("Iteration: " + i);
}

/**
* Output:
* Iteration: 1
* Iteration: 2
*/

continue Statement

Skips the current iteration and proceeds with the next one.

for (int i = 1; i <= 5; i++) {
    if (i == 3) {
        continue;
    }

    System.out.println("Iteration: " + i);
}

/**
* Output:
* Iteration: 1
* Iteration: 2
* Iteration: 4
* Iteration: 5
*/

return Statement

Exits from a method and returns a value.

public static int sum(int a, int b) {
    return a + b;
}

Conclusion

Control flow statements are essential for managing the execution flow of a Java program. They enable decision-making, iteration, and flow control, ensuring efficiency and readability. By mastering these concepts, you'll gain greater control over program logic and execution paths, setting a strong foundation for advanced programming topics.

Stay tuned for the next topic in Java Short Notes! 🚀