Control Flow Statements in Java – Loops & Conditional Statements

 

Control Flow Statements in Java – Loops & Conditional Statements

Control flow statements in Java allow you to control the execution of your code based on conditions and loops. In this post, we will explore:

1. Conditional Statements – if, if-else, if-else-if, switch
2. Looping Statements – for, while, do-while
3. Jump Statements – break, continue, return

Let’s break them down with examples.

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1. Conditional Statements in Java

1.1 if Statement

The if statement executes a block of code if a condition is true.

Syntax:

if (condition) {
    // Code to execute if condition is true
}

Example:

public class IfExample {
    public static void main(String[] args) {
        int age = 20;
        if (age >= 18) {
            System.out.println("You are eligible to vote.");
        }
    }
}

1.2 if-else Statement

Executes one block of code if the condition is true, otherwise executes another block.

Example:

public class IfElseExample {
    public static void main(String[] args) {
        int num = 10;
        if (num % 2 == 0) {
            System.out.println("Even number");
        } else {
            System.out.println("Odd number");
        }
    }
}

1.3 if-else-if Ladder

Used to test multiple conditions.

Example:

public class IfElseIfExample {
    public static void main(String[] args) {
        int marks = 85;
        if (marks >= 90) {
            System.out.println("Grade: A");
        } else if (marks >= 75) {
            System.out.println("Grade: B");
        } else if (marks >= 50) {
            System.out.println("Grade: C");
        } else {
            System.out.println("Fail");
        }
    }
}

1.4 switch Statement

Used when multiple conditions depend on a single variable.

Example:

public class SwitchExample {
    public static void main(String[] args) {
        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");
        }
    }
}

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2. Looping Statements in Java

Loops execute a block of code multiple times based on a condition.

2.1 for Loop

Used when the number of iterations is known.

Example:

public class ForLoopExample {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            System.out.println("Iteration: " + i);
        }
    }
}

2.2 while Loop

Executes the block as long as the condition is true.

Example:

public class WhileExample {
    public static void main(String[] args) {
        int i = 1;
        while (i <= 5) {
            System.out.println("Count: " + i);
            i++;
        }
    }
}

2.3 do-while Loop

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

Example:

public class DoWhileExample {
    public static void main(String[] args) {
        int i = 1;
        do {
            System.out.println("Number: " + i);
            i++;
        } while (i <= 5);
    }
}

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3. Jump Statements in Java

3.1 break Statement

Used to exit a loop or switch case.

Example:

public class BreakExample {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            if (i == 3) {
                break;
            }
            System.out.println(i);
        }
    }
}

3.2 continue Statement

Skips the current iteration and continues to the next.

Example:

public class ContinueExample {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            if (i == 3) {
                continue;
            }
            System.out.println(i);
        }
    }
}

3.3 return Statement

Exits from a method and returns a value.

Example:

public class ReturnExample {
    public static void main(String[] args) {
        System.out.println("Sum: " + add(5, 10));
    }

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

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Conclusion

Control flow statements help in making decisions and repeating actions. They are essential for writing efficient Java programs. In the next post, we will discuss Java Methods – Creating & Using Functions.