Programming and Java Fundamentals

Break, Continue, and Loop Control

ReadingPreview

You are viewing a free preview lesson.

Lesson Overview

Loop সাধারণত condition false না হওয়া পর্যন্ত চলতে থাকে।

কিন্তু কিছু situation-এ আমাদের প্রয়োজন হতে পারে:

Expected result পাওয়ার সঙ্গে সঙ্গে loop বন্ধ করা
একটি invalid value skip করে পরবর্তী iteration-এ যাওয়া
User exit option select করলে menu loop শেষ করা
একটি String-এর মধ্যে target character পাওয়া গেলে search বন্ধ করা
Nested loop-এর outer loop থেকে বের হওয়া

Java loop-এর execution control করার জন্য প্রধানত দুটি statement দেয়:

break
continue

এই lesson-এ আমরা শিখব:

break কীভাবে loop বন্ধ করে
continue কীভাবে current iteration skip করে
Search loop
Sentinel এবং menu exit
Input filtering
break এবং continue in for, while, and do-while
Nested loop control
Labeled break
Labeled continue
Early exit এবং readable loop design
Common control-flow mistakes

Learning Objectives

এই lesson শেষ করার পর আপনি পারবেন:

break ব্যবহার করে loop early terminate করতে
continue ব্যবহার করে current iteration skip করতে
Search result পাওয়া গেলে loop বন্ধ করতে
Invalid data skip করতে
Infinite menu loop safely exit করতে
Nested loop-এর execution control করতে
Labeled break এবং labeled continue বুঝতে
break ও continue-এর difference explain করতে
Common loop-control bugs শনাক্ত করতে
Cleaner এবং readable loop লিখতে

What Is Loop Control?

Loop control হলো loop-এর normal execution flow পরিবর্তন করা।

Normal loop:

for (int number = 1; number <= 5; number++) {
    System.out.println(number);
}

Output:

break ব্যবহার করলে loop আগেই শেষ হতে পারে।

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

    System.out.println(number);
}

Output:

1
2

continue ব্যবহার করলে একটি iteration skip হতে পারে।

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

    System.out.println(number);
}

Output:

The `break` Statement

break nearest loop বা switch statement immediately শেষ করে।

Syntax:

break;

Loop-এর মধ্যে:

for (...) {
    if (condition) {
        break;
    }
}

Basic Break Example

for (int number = 1; number <= 10; number++) {
    if (number == 5) {
        break;
    }

    System.out.println(number);
}

Output:

যখন:

number == 5

true হয়েছে, break loop বন্ধ করেছে।

5 print হয়নি, কারণ break print statement-এর আগে ছিল।

Code After the Loop

for (int number = 1; number <= 10; number++) {
    if (number == 5) {
        break;
    }

    System.out.println(number);
}

System.out.println("Loop finished");

Output:

1
2
3
4
Loop finished

break শুধু loop শেষ করে। পুরো method বা program শেষ করে না।

Break Position Matters

Break Before Printing

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

    System.out.println(number);
}

Output:

1
2

Break After Printing

for (int number = 1; number <= 5; number++) {
    System.out.println(number);

    if (number == 3) {
        break;
    }
}

Output:

1
2
3

Statement order result পরিবর্তন করে।

Break in a While Loop

int number = 1;

while (number <= 10) {
    if (number == 5) {
        break;
    }

    System.out.println(number);

    number++;
}

Output:

Break in a Do-While Loop

int number = 1;

do {
    if (number == 5) {
        break;
    }

    System.out.println(number);

    number++;
} while (number <= 10);

Output:

Searching with Break

ধরা যাক একটি String-এর মধ্যে target character খুঁজতে হবে।

String text = "Java Foundation";
char target = 'F';
int foundIndex = -1;

for (
        int index = 0;
        index < text.length();
        index++
) {
    if (text.charAt(index) == target) {
        foundIndex = index;

        break;
    }
}

System.out.println(
        "Found index: " + foundIndex
);

Output:

Found index: 5

Target পাওয়া গেলে remaining characters check করার প্রয়োজন নেই।

Why Break Helps Search Performance

Without break:

for (
        int index = 0;
        index < text.length();
        index++
) {
    if (text.charAt(index) == target) {
        foundIndex = index;
    }
}

Loop পুরো String process করবে।

With break:

if (text.charAt(index) == target) {
    foundIndex = index;
    break;
}

First match পাওয়ার সঙ্গে সঙ্গে loop শেষ হবে।

Finding Whether a Value Exists

String text = "Learn Java";
char target = 'J';
boolean found = false;

for (
        int index = 0;
        index < text.length();
        index++
) {
    if (text.charAt(index) == target) {
        found = true;

        break;
    }
}

System.out.println(
        "Found: " + found
);

Output:

Found: true

Break in an Infinite Loop

Intentional infinite loop থেকে condition অনুযায়ী বের হতে break ব্যবহার করা যায়।

int number = 1;

while (true) {
    System.out.println(number);

    if (number == 5) {
        break;
    }

    number++;
}

Output:

while (true) নিজে শেষ হয় না। break exit condition দেয়।

Menu Loop with Break

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner =
                new Scanner(System.in);

        while (true) {
            System.out.println();
            System.out.println("1. View courses");
            System.out.println("2. Create course");
            System.out.println("3. Exit");

            System.out.print(
                    "Choose an option: "
            );

            int option =
                    Integer.parseInt(
                            scanner
                                    .nextLine()
                                    .strip()
                    );

            if (option == 3) {
                System.out.println("Goodbye");

                break;
            }

            switch (option) {
                case 1 ->
                        System.out.println(
                                "Loading courses"
                        );

                case 2 ->
                        System.out.println(
                                "Opening course form"
                        );

                default ->
                        System.out.println(
                                "Invalid option"
                        );
            }
        }

        scanner.close();
    }
}

Break and Sentinel Values

Sentinel loop:

int total = 0;

while (true) {
    System.out.print(
            "Enter a number or -1 to stop: "
    );

    int number =
            Integer.parseInt(
                    scanner
                            .nextLine()
                            .strip()
            );

    if (number == -1) {
        break;
    }

    total += number;
}

Sentinel input process হওয়ার আগে break করা হয়েছে।

তাই -1 total-এর মধ্যে যোগ হবে না।

Limited Password Attempts

import java.util.Scanner;

public class Main {

    static final String CORRECT_PASSWORD =
            "java123";

    static final int MAXIMUM_ATTEMPTS = 3;

    public static void main(String[] args) {
        Scanner scanner =
                new Scanner(System.in);

        boolean authenticated = false;

        for (
                int attempt = 1;
                attempt <= MAXIMUM_ATTEMPTS;
                attempt++
        ) {
            System.out.print(
                    "Enter password: "
            );

            String password =
                    scanner.nextLine();

            if (
                    CORRECT_PASSWORD.equals(
                            password
                    )
            ) {
                authenticated = true;

                break;
            }

            System.out.println(
                    "Incorrect password"
            );
        }

        if (authenticated) {
            System.out.println(
                    "Access granted"
            );
        } else {
            System.out.println(
                    "Account locked"
            );
        }

        scanner.close();
    }
}

Correct password পাওয়া গেলে remaining attempts unnecessary, তাই break।

What Is Continue?

continue current iteration-এর remaining statements skip করে পরবর্তী iteration-এ যায়।

Syntax:

continue;

Example:

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

    System.out.println(number);
}

Output:

Loop শেষ হয়নি। শুধু number == 3 iteration-এর remaining code skip হয়েছে।

How Continue Works in a For Loop

for (initialization; condition; update) {
    if (skipCondition) {
        continue;
    }

    // Remaining body
}

continue হলে:

Current body-এর remaining statements skip হয়
for loop-এর update expression execute হয়
Condition আবার check হয়
Next iteration শুরু হয়

Continue Example with Even Numbers

for (int number = 1; number <= 10; number++) {
    if (number % 2 != 0) {
        continue;
    }

    System.out.println(number);
}

Output:

Odd number হলে current iteration skip হয়েছে।

Continue Example with Odd Numbers

for (int number = 1; number <= 10; number++) {
    if (number % 2 == 0) {
        continue;
    }

    System.out.println(number);
}

Output:

Filtering Invalid Values

int total = 0;

for (int number = -3; number <= 5; number++) {
    if (number < 0) {
        continue;
    }

    total += number;
}

System.out.println(total);

Processed values:

Output:

Negative values skip হয়েছে।

Skipping Invalid Marks

int[] marks = {
        80,
        -10,
        90,
        120,
        70
};

int validTotal = 0;
int validCount = 0;

for (int mark : marks) {
    if (mark < 0 || mark > 100) {
        continue;
    }

    validTotal += mark;
    validCount++;
}

Enhanced for loop এবং arrays future lesson-এ বিস্তারিত শেখানো হবে।

Core idea:

Invalid value skip করুন, valid value process করুন।

Continue in a While Loop

while loop-এ continue ব্যবহার করার সময় update carefully handle করতে হয়।

Correct:

int number = 0;

while (number < 5) {
    number++;

    if (number == 3) {
        continue;
    }

    System.out.println(number);
}

Output:

Update continue-এর আগে হয়েছে।

Continue Causing an Infinite While Loop

Wrong:

int number = 1;

while (number <= 5) {
    if (number == 3) {
        continue;
    }

    System.out.println(number);

    number++;
}

Execution:

number = 3
condition true
continue
number++ skipped
number remains 3

Loop infinite হয়ে যায়।

Fixing Continue in While

Option 1: update first।

int number = 0;

while (number < 5) {
    number++;

    if (number == 3) {
        continue;
    }

    System.out.println(number);
}

Option 2: update before continue।

int number = 1;

while (number <= 5) {
    if (number == 3) {
        number++;

        continue;
    }

    System.out.println(number);

    number++;
}

প্রথম version সাধারণত cleaner।

Continue in Do-While

int number = 0;

do {
    number++;

    if (number == 3) {
        continue;
    }

    System.out.println(number);
} while (number < 5);

Output:

continue হলে do-while condition check হয়, তারপর next iteration শুরু হয়।

Break vs Continue

Statement	Effect
`break`	পুরো nearest loop শেষ করে
`continue`	শুধু current iteration skip করে
`return`	পুরো method শেষ করে

Break Example

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

    System.out.println(number);
}

Output:

1
2

Continue Example

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

    System.out.println(number);
}

Output:

Return Is Different

static void displayNumbers() {
    for (int number = 1; number <= 5; number++) {
        if (number == 3) {
            return;
        }

        System.out.println(number);
    }

    System.out.println("Method completed");
}

Output:

1
2

return method শেষ করেছে।

তাই:

Method completed

print হয়নি।

Continue for Input Filtering

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner =
                new Scanner(System.in);

        int total = 0;
        int validCount = 0;

        for (int inputNumber = 1; inputNumber <= 5; inputNumber++) {
            System.out.print(
                    "Enter mark "
                    + inputNumber
                    + ": "
            );

            int mark =
                    Integer.parseInt(
                            scanner
                                    .nextLine()
                                    .strip()
                    );

            if (mark < 0 || mark > 100) {
                System.out.println(
                        "Invalid mark skipped"
                );

                continue;
            }

            total += mark;
            validCount++;
        }

        System.out.println(
                "Valid total: " + total
        );

        System.out.println(
                "Valid marks: " + validCount
        );

        scanner.close();
    }
}

এখানে invalid input-এর replacement নেওয়া হচ্ছে না। এটি শুধু skip করা হচ্ছে।

Avoiding Deep Nesting with Continue

Without continue:

for (int mark : marks) {
    if (mark >= 0 && mark <= 100) {
        total += mark;
        count++;

        if (mark >= 40) {
            passedCount++;
        }
    }
}

With continue:

for (int mark : marks) {
    if (mark < 0 || mark > 100) {
        continue;
    }

    total += mark;
    count++;

    if (mark >= 40) {
        passedCount++;
    }
}

Invalid case আগে skip করায় main logic less nested।

Continue as a Guard

for (int number = 1; number <= 10; number++) {
    if (number % 2 != 0) {
        continue;
    }

    int square =
            number * number;

    System.out.println(
            number + " → " + square
    );
}

Output:

Nested Loops and Break

Normal break শুধু nearest loop শেষ করে।

for (int row = 1; row <= 3; row++) {
    for (int column = 1; column <= 3; column++) {
        if (column == 2) {
            break;
        }

        System.out.println(
                "Row "
                + row
                + ", Column "
                + column
        );
    }
}

Output:

Row 1, Column 1
Row 2, Column 1
Row 3, Column 1

break inner loop শেষ করেছে।

Outer loop continue করেছে।

Nested Loops and Continue

for (int row = 1; row <= 3; row++) {
    for (int column = 1; column <= 3; column++) {
        if (column == 2) {
            continue;
        }

        System.out.println(
                "Row "
                + row
                + ", Column "
                + column
        );
    }
}

Output:

Row 1, Column 1
Row 1, Column 3
Row 2, Column 1
Row 2, Column 3
Row 3, Column 1
Row 3, Column 3

Inner loop-এর column 2 iteration skip হয়েছে।

Searching a Grid

int targetRow = 2;
int targetColumn = 3;
boolean found = false;

for (int row = 1; row <= 3; row++) {
    for (int column = 1; column <= 3; column++) {
        if (
                row == targetRow
                && column == targetColumn
        ) {
            found = true;

            break;
        }
    }

    if (found) {
        break;
    }
}

System.out.println(
        "Found: " + found
);

Inner break শুধু inner loop বন্ধ করে।

তারপর outer loop বন্ধ করতে second break প্রয়োজন হয়েছে।

Labeled Break

Label ব্যবহার করে নির্দিষ্ট outer loop থেকে সরাসরি বের হওয়া যায়।

Syntax:

labelName:
for (...) {
    for (...) {
        break labelName;
    }
}

Example:

search:
for (int row = 1; row <= 3; row++) {
    for (int column = 1; column <= 3; column++) {
        if (row == 2 && column == 3) {
            System.out.println(
                    "Target found"
            );

            break search;
        }

        System.out.println(
                "Checking "
                + row
                + ", "
                + column
        );
    }
}

Output:

Checking 1, 1
Checking 1, 2
Checking 1, 3
Checking 2, 1
Checking 2, 2
Target found

break search; labeled outer loop শেষ করেছে।

Label Syntax

outerLoop:
for (...) {
}

Label:

outerLoop

তারপর:

break outerLoop;

Label identifier naming rule follow করে।

Labeled Continue

Labeled continue outer loop-এর next iteration-এ যেতে পারে।

outer:
for (int row = 1; row <= 3; row++) {
    for (int column = 1; column <= 3; column++) {
        if (column == 2) {
            continue outer;
        }

        System.out.println(
                "Row "
                + row
                + ", Column "
                + column
        );
    }
}

Output:

Row 1, Column 1
Row 2, Column 1
Row 3, Column 1

যখন column 2, current outer iteration-এর remaining inner work skip হয়ে next row শুরু হয়েছে।

Use Labels Carefully

Labeled control flow powerful, কিন্তু overuse করলে code বুঝতে কঠিন হয়।

Prefer করতে পারেন:

Helper method
Boolean flag
Early return
Clear search abstraction

Labels mainly useful যখন nested loop থেকে controlled exit প্রয়োজন এবং alternative আরও complex।

Breaking from a Search Method

Method-এর মধ্যে result পাওয়া গেলে return অনেক সময় labeled break-এর চেয়ে cleaner।

static boolean containsCharacter(
        String text,
        char target
) {
    for (
            int index = 0;
            index < text.length();
            index++
    ) {
        if (text.charAt(index) == target) {
            return true;
        }
    }

    return false;
}

Methods পরবর্তী module-এ বিস্তারিত শেখানো হবে।

Search for the First Divisible Number

int foundNumber = -1;

for (int number = 10; number <= 100; number++) {
    if (
            number % 7 == 0
            && number % 5 == 0
    ) {
        foundNumber = number;

        break;
    }
}

System.out.println(
        "First match: " + foundNumber
);

Output:

First match: 35

Search for the First Uppercase Letter

String text = "java Foundation";
char uppercaseLetter = '\0';

for (
        int index = 0;
        index < text.length();
        index++
) {
    char character =
            text.charAt(index);

    if (Character.isUpperCase(character)) {
        uppercaseLetter = character;

        break;
    }
}

if (uppercaseLetter != '\0') {
    System.out.println(
            "First uppercase: "
            + uppercaseLetter
    );
} else {
    System.out.println(
            "No uppercase letter found"
    );
}

Skipping Whitespace

String text = "Java Foundation";

for (
        int index = 0;
        index < text.length();
        index++
) {
    char character =
            text.charAt(index);

    if (Character.isWhitespace(character)) {
        continue;
    }

    System.out.println(character);
}

Output:

J
a
v
a
F
o
u
n
d
a
t
i
o
n

Space skip হয়েছে।

Counting Only Letters

String text = "Java 21!";
int letterCount = 0;

for (
        int index = 0;
        index < text.length();
        index++
) {
    char character =
            text.charAt(index);

    if (!Character.isLetter(character)) {
        continue;
    }

    letterCount++;
}

System.out.println(
        "Letters: " + letterCount
);

Output:

Letters: 4

Processing Positive Numbers Only

int[] numbers = {
        10,
        -5,
        20,
        0,
        -2,
        8
};

int total = 0;

for (int number : numbers) {
    if (number <= 0) {
        continue;
    }

    total += number;
}

System.out.println(total);

Output:

Processed:

10 + 20 + 8

Practical Example: First Passing Mark

int[] marks = {
        20,
        35,
        42,
        80
};

int firstPassingMark = -1;

for (int mark : marks) {
    if (mark >= 40) {
        firstPassingMark = mark;

        break;
    }
}

System.out.println(
        "First passing mark: "
        + firstPassingMark
);

Output:

First passing mark: 42

Practical Example: Valid Mark Statistics

int[] marks = {
        80,
        -5,
        90,
        110,
        30,
        75
};

int total = 0;
int validCount = 0;
int passedCount = 0;

for (int mark : marks) {
    if (mark < 0 || mark > 100) {
        continue;
    }

    total += mark;
    validCount++;

    if (mark >= 40) {
        passedCount++;
    }
}

System.out.println(
        "Valid marks: " + validCount
);

System.out.println(
        "Passed: " + passedCount
);

if (validCount > 0) {
    double average =
            total / (double) validCount;

    System.out.println(
            "Average: "
            + "%.2f".formatted(
                    average
            )
    );
}

Practical Example: Command Loop

import java.util.Locale;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner =
                new Scanner(System.in);

        while (true) {
            System.out.print(
                    "Enter a command "
                    + "(help, status, exit): "
            );

            String command =
                    scanner
                            .nextLine()
                            .strip()
                            .toLowerCase(
                                    Locale.ROOT
                            );

            if (command.isBlank()) {
                System.out.println(
                        "Command is required"
                );

                continue;
            }

            if (command.equals("exit")) {
                System.out.println(
                        "Application closed"
                );

                break;
            }

            switch (command) {
                case "help" ->
                        System.out.println(
                                "Available commands: "
                                + "help, status, exit"
                        );

                case "status" ->
                        System.out.println(
                                "Application is running"
                        );

                default ->
                        System.out.println(
                                "Unknown command"
                        );
            }
        }

        scanner.close();
    }
}

Practical Example: Input Until Valid Number

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner =
                new Scanner(System.in);

        int validNumber;

        while (true) {
            System.out.print(
                    "Enter a number between 1 and 10: "
            );

            int number =
                    Integer.parseInt(
                            scanner
                                    .nextLine()
                                    .strip()
                    );

            if (number < 1 || number > 10) {
                System.out.println(
                        "Number is outside the range"
                );

                continue;
            }

            validNumber = number;

            break;
        }

        System.out.println(
                "Accepted number: "
                + validNumber
        );

        scanner.close();
    }
}

When to Use Break

Use break when:

Search result পাওয়া গেছে
Exit option selected
Sentinel পাওয়া গেছে
Correct password entered
Further processing unnecessary
Invalid system state requires loop termination
Infinite loop-এর exit condition reached

When to Use Continue

Use continue when:

Invalid item skip করতে হবে
Current value process করা উচিত নয়
Filter condition fail করেছে
Empty input ignore করতে হবে
Specific number বা character বাদ দিতে হবে
Main processing block-এর nesting কমাতে হবে

When Not to Use Break or Continue

Overuse করলে loop flow difficult to follow হতে পারে।

Hard to read:

for (...) {
    if (...) {
        continue;
    }

    if (...) {
        break;
    }

    if (...) {
        continue;
    }

    if (...) {
        break;
    }
}

Improve by:

Conditions simplify করা
Helper method extract করা
Clear variable names ব্যবহার করা
Main loop responsibility ছোট রাখা

Common Error: Code After Break

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

        System.out.println("Stopped");
    }
}

break-এর পরের statement unreachable।

Compiler error হতে পারে।

Correct:

if (number == 3) {
    System.out.println("Stopped");

    break;
}

Common Error: Code After Continue

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

        System.out.println("Skipped");
    }
}

continue-এর পরের statement unreachable।

Correct:

if (number == 3) {
    System.out.println("Skipped");

    continue;
}

Common Error: Expecting Break to End All Loops

for (int row = 1; row <= 3; row++) {
    for (int column = 1; column <= 3; column++) {
        if (column == 2) {
            break;
        }
    }
}

break শুধু inner loop শেষ করে।

Outer loop চলতে থাকে।

সব loop end করতে:

Flag ব্যবহার করুন
Labeled break
Method থেকে return
Logic refactor করুন

Common Error: Continue Before Update in While

Wrong:

int number = 1;

while (number <= 5) {
    if (number == 3) {
        continue;
    }

    number++;
}

number 3-এ আটকে যায়।

Common Error: Processing Sentinel

Wrong:

while (true) {
    int number =
            Integer.parseInt(
                    scanner.nextLine()
            );

    total += number;

    if (number == -1) {
        break;
    }
}

-1 total-এর মধ্যে যোগ হয়েছে।

Correct:

if (number == -1) {
    break;
}

total += number;

Common Error: Wrong Continue Condition

Requirement:

Only valid marks process করুন।

Wrong:

if (mark >= 0 && mark <= 100) {
    continue;
}

total += mark;

এখানে valid marks skip হচ্ছে।

Correct:

if (mark < 0 || mark > 100) {
    continue;
}

total += mark;

Common Error: Breaking Too Early

for (int number = 1; number <= 10; number++) {
    break;

    System.out.println(number);
}

Loop first iteration-এই শেষ হয়ে যায় এবং print statement unreachable।

Common Error: Continue Hides Important Work

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

    processedCount++;
}

যদি processedCount সব input count করার জন্য হয়, তাহলে 3 incorrectly বাদ পড়ছে।

continue কোন statements skip করছে তা carefully review করুন।

Common Error: Label Overuse

first:
for (...) {
    second:
    for (...) {
        third:
        for (...) {
            // Complex jumps
        }
    }
}

এটি maintain করা কঠিন।

Nested logic method বা separate function-এ ভাগ করা better হতে পারে।

Testing Loop Control

Test করুন:

Break condition first iteration-এ true
Break condition middle iteration-এ true
Break condition কখনো true নয়
Continue condition first value-এ true
Consecutive values skip হয়
সব values skip হয়
কোনো value skip হয় না
Sentinel first input
Sentinel processing-এর আগে check হয়
Nested break কোন loop শেষ করে
While continue-এর আগে update হয় কি না
Search target missing হলে default value সঠিক থাকে কি না

Trace Example: Break

for (int number = 1; number <= 5; number++) {
    if (number == 4) {
        break;
    }

    System.out.println(number);
}

`number`	Condition `number == 4`	Action
1	false	Print `1`
2	false	Print `2`
3	false	Print `3`
4	true	Break

Output:

1
2
3

Trace Example: Continue

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

    System.out.println(number);
}

`number`	Condition `number == 3`	Action
1	false	Print `1`
2	false	Print `2`
3	true	Skip
4	false	Print `4`
5	false	Print `5`

Output:

Practice Exercises

Exercise 1: Stop at Five

1 থেকে 10 পর্যন্ত loop চালান।

5 আসার আগে loop stop করুন।

Expected output:

Exercise 2: Include Five Before Stopping

1 থেকে print করুন এবং 5 print হওয়ার পরে loop stop করুন।

Expected output:

Exercise 3: Skip Five

1 থেকে 10 পর্যন্ত print করুন, কিন্তু 5 বাদ দিন।

Exercise 4: Print Even Numbers with Continue

1 থেকে 20 পর্যন্ত odd values skip করে even values print করুন।

Exercise 5: Print Odd Numbers with Continue

Even values skip করুন।

Exercise 6: Search for a Character

একটি String-এর মধ্যে প্রথম 'a' character-এর index বের করুন।

Match পাওয়া গেলে loop stop করুন।

Exercise 7: Search for a Number

1 থেকে 100-এর মধ্যে প্রথম number খুঁজুন, যা 6 এবং 7 উভয় দিয়ে divisible।

Expected:

Exercise 8: Sentinel Total

User numbers input দেবে।

-1 দিলে loop stop হবে।

Sentinel total-এর মধ্যে যোগ করবেন না।

Exercise 9: Command Menu

Commands:

help
status
exit

Rules:

Blank command হলে continue
exit হলে break
Other commands process করুন

Exercise 10: Skip Invalid Marks

Five marks read করুন।

Range 0–100-এর বাইরে হলে skip করুন।

Calculate:

Valid count
Total
Average

Exercise 11: Password Attempts

Maximum three attempts দিন।

Correct password পেলে immediately loop stop করুন।

Exercise 12: Fix the Infinite Continue Loop

int number = 1;

while (number <= 5) {
    if (number == 3) {
        continue;
    }

    System.out.println(number);

    number++;
}

Exercise 13: Nested Break

একটি 3 × 3 grid iterate করুন।

প্রতিটি row-তে column 2 এলে inner loop stop করুন।

Expected:

1,1
2,1
3,1

Exercise 14: Labeled Break

Nested loop-এর মধ্যে target coordinate পাওয়া গেলে দুই loop থেকেই বের হয়ে যান।

Exercise 15: Labeled Continue

Column 2 এলে current row-এর remaining columns skip করে next row শুরু করুন।

Exercise 16: Skip Whitespace

একটি sentence-এর সব non-whitespace characters নতুন line-এ print করুন।

Exercise 17: Count Letters Only

Input:

Java 21!

Digits, spaces এবং symbols skip করে শুধু letter count করুন।

Expected:

Exercise 18: First Passing Mark

Marks:

20, 35, 42, 80

First passing mark খুঁজে loop stop করুন।

Passing mark:

Exercise 19: Positive Values Only

একটি number list থেকে zero এবং negative values skip করে positive total calculate করুন।

Exercise 20: Explain the Difference

নিজের ভাষায় explain করুন:

break
continue
return

Knowledge Check

Question 1

break কী করে?

Question 2

continue কী করে?

Question 3

break-এর পরে loop-এর বাইরের code execute হয় কি?

Question 4

continue কি পুরো loop শেষ করে?

Question 5

for loop-এ continue-এর পরে কোন part execute হয়?

Question 6

while loop-এ continue কেন infinite loop ঘটাতে পারে?

Question 7

Search loop-এ break কেন useful?

Question 8

Normal break nested loop-এর কোন loop শেষ করে?

Question 9

Labeled break কী করে?

Question 10

Labeled continue কী করে?

Question 11

Sentinel কখন check করা উচিত?

Question 12

break এবং return-এর পার্থক্য কী?

Question 13

Invalid item filter করতে কোন statement useful?

Question 14

Correct password পাওয়া গেলে কোন statement useful?

Question 15

continue-এর পরের statements কি current iteration-এ execute হয়?

Question 16

break-এর পরের statements কি current loop iteration-এ execute হয়?

Question 17

Arrow-style switch-এ break সাধারণত প্রয়োজন হয় কি?

Question 18

Label overuse কেন avoid করা উচিত?

Question 19

while (true) loop কীভাবে safely শেষ করা যায়?

Question 20

Loop control test করার একটি গুরুত্বপূর্ণ boundary case কী?

Knowledge Check Answers

Answer 1

Nearest loop বা switch immediately শেষ করে।

Answer 2

Current iteration-এর remaining statements skip করে next iteration-এ যায়।

Answer 3

হ্যাঁ। break শুধু loop শেষ করে।

Answer 4

না।

Answer 5

Update expression execute হয়, তারপর condition check হয়।

Answer 6

Counter update continue-এর পরে থাকলে update skip হতে পারে এবং condition variable একই value-তে আটকে যেতে পারে।

Answer 7

Target পাওয়া গেলে unnecessary remaining iterations বন্ধ করে।

Answer 8

Nearest বা innermost loop।

Answer 9

Named outer loop পর্যন্ত execution terminate করতে পারে।

Answer 10

Named outer loop-এর next iteration শুরু করে।

Answer 11

Sentinel data process করার আগে।

Answer 12

break loop শেষ করে। return পুরো method শেষ করে।

Answer 13

continue

Answer 14

break

Answer 15

না।

Answer 16

না।

Answer 17

না।

Answer 18

Control flow বুঝতে এবং maintain করতে কঠিন হয়ে যায়।

Answer 19

Clear exit condition এবং break, return বা exception ব্যবহার করে।

Answer 20

Break condition first iteration-এই true হওয়া, অথবা sentinel প্রথম input হিসেবে আসা।

Lesson Summary

এই lesson-এ আমরা শিখেছি:

break nearest loop immediately শেষ করে
continue current iteration-এর remaining code skip করে
break পুরো method শেষ করে না
return method শেষ করে
Search result পাওয়া গেলে break useful
Sentinel process করার আগে check করতে হয়
Infinite menu loop থেকে exit করতে break ব্যবহার করা যায়
Invalid values skip করতে continue useful
continue nesting কমাতে guard হিসেবে কাজ করতে পারে
for loop-এ continue update expression-এর দিকে যায়
while loop-এ continue counter update skip করলে infinite loop হতে পারে
Normal break nested loop-এর শুধু nearest loop শেষ করে
Labeled break outer loop শেষ করতে পারে
Labeled continue outer loop-এর next iteration শুরু করতে পারে
Labels carefully ব্যবহার করা উচিত
Break বা continue-এর পরের statement unreachable হতে পারে
Loop control statement-এর position result পরিবর্তন করে
Overuse করলে control flow difficult to understand হতে পারে
Clear conditions এবং small loop body maintainability improve করে

Next Lesson

পরবর্তী lesson-এ আমরা Module 1-এর practical project তৈরি করব:

Build a Console-Based Grade Calculator

আমরা ব্যবহার করব:

Variables
Primitive data types
Strings
Operators
Type conversion
Scanner
Conditional statements
switch
for loop
while বা do-while
break এবং continue
Input validation
Total, average, grade এবং final result calculation

Lesson Overview

Learning Objectives

What Is Loop Control?

The break Statement

Basic Break Example

Code After the Loop

Break Position Matters

Break Before Printing

Break After Printing

Break in a While Loop

Break in a Do-While Loop

Searching with Break

Why Break Helps Search Performance

Finding Whether a Value Exists

Break in an Infinite Loop

Menu Loop with Break

Break and Sentinel Values

Limited Password Attempts

What Is Continue?

How Continue Works in a For Loop

Continue Example with Even Numbers

Continue Example with Odd Numbers

Filtering Invalid Values

Skipping Invalid Marks

Continue in a While Loop

Continue Causing an Infinite While Loop

Fixing Continue in While

Continue in Do-While

Break vs Continue

Break Example

Continue Example

Return Is Different

Continue for Input Filtering

Avoiding Deep Nesting with Continue

Continue as a Guard

Nested Loops and Break

Nested Loops and Continue

Searching a Grid

Labeled Break

Label Syntax

Labeled Continue

Use Labels Carefully

Breaking from a Search Method

Search for the First Divisible Number

Search for the First Uppercase Letter

Skipping Whitespace

Counting Only Letters

Processing Positive Numbers Only

Practical Example: First Passing Mark

Practical Example: Valid Mark Statistics

Practical Example: Command Loop

Practical Example: Input Until Valid Number

When to Use Break

When to Use Continue

When Not to Use Break or Continue

Common Error: Code After Break

Common Error: Code After Continue

Common Error: Expecting Break to End All Loops

Common Error: Continue Before Update in While

Common Error: Processing Sentinel

Common Error: Wrong Continue Condition

Common Error: Breaking Too Early

Common Error: Continue Hides Important Work

Common Error: Label Overuse

Testing Loop Control

Trace Example: Break

Trace Example: Continue

Practice Exercises

Exercise 1: Stop at Five

Exercise 2: Include Five Before Stopping

Exercise 3: Skip Five

Exercise 4: Print Even Numbers with Continue

Exercise 5: Print Odd Numbers with Continue

Exercise 6: Search for a Character

Exercise 7: Search for a Number

Exercise 8: Sentinel Total

Exercise 9: Command Menu

Exercise 10: Skip Invalid Marks

Exercise 11: Password Attempts

Exercise 12: Fix the Infinite Continue Loop

The `break` Statement