Flow Control in Java: A Complete Guide

Java Functions And Methods

Java Foundation

Java Flow Control

Java Inner Classes

Java 8 Features

Java File I/o

Java Multithreading

Java Arrays And Strings

Java Exception Handling

Java Classes

Java OOP's

Java Collections Framework

Flow Control in Java

Flow Control refers to the order in which individual statements, instructions, or function calls are executed in a programming language. Java provides several structures to control the flow of a program. These include decision-making constructs, loops, and branching statements that enable programmers to control how the code executes based on various conditions.

We'll cover each flow control concept, from basic to advanced, with examples.

Sequential Flow (Basic)

In the sequential flow, the program executes statements one by one, in the order in which they appear. This is the most basic form of flow control, where the execution flows sequentially from top to bottom.

Code Example

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public class SequentialExample {    public static void main(String[] args) {        int x = 10; // Step 1        System.out.println("Value of x: " + x); // Step 2        x = x + 5; // Step 3        System.out.println("Updated value of x: " + x); // Step 4    }}

Output

Value of x: 10
Updated value of x: 15

Here, each line executes in sequence, with no branching or loops.

Decision-Making Statements

Decision-making statements in programming are constructs that allow a program to execute different sets of instructions based on certain conditions. Here's a concise definition:

Decision-making statements are programming constructs that enable conditional execution of code based on the evaluation of specified criteria. They allow programs to make choices and follow different paths of execution depending on whether certain conditions are true or false.

The most common types of decision-making statements include:

If statements
If-else statements
if-else-if Ladder
Switch statements (in some languages)

if Statement

The if statement allows the program to make a decision based on a condition. If the condition is true, the code inside the if block is executed; otherwise, it is skipped.

Syntax:

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

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public class IfExample {    public static void main(String[] args) {        int number = 10;        if (number > 5) {            System.out.println("Number is greater than 5");        }    }}

Output

Number is greater than 5

if-else Statement

The if-else statement provides an alternative path if the condition in the if statement is false.

Syntax:

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

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public class IfElseExample {    public static void main(String[] args) {        int number = 3;        if (number > 5) {            System.out.println("Number is greater than 5");        } else {            System.out.println("Number is not greater than 5");        }    }}

Output

Number is not greater than 5

if-else if Ladder

The if-else if ladder is used when there are multiple conditions to check, one after the other.

Syntax:

if (condition1) {
    // Code to execute if condition1 is true
} else if (condition2) {
    // Code to execute if condition2 is true
} else {
    // Code to execute if none of the conditions are true
}

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public class IfElseIfExample {    public static void main(String[] args) {        int number = 10;        if (number < 5) {            System.out.println("Number is less than 5");        } else if (number == 10) {            System.out.println("Number is equal to 10");        } else {            System.out.println("Number is greater than 5 and not equal to 10");        }    }}

Output

Number is equal to 10

switch Statement

The switch statement allows you to execute different code blocks based on the value of a variable or expression. It is often used as a more readable alternative to multiple if-else if statements.

Syntax:

switch (expression) {
    case value1:
        // Code to execute if expression == value1
        break;
    case value2:
        // Code to execute if expression == value2
        break;
    default:
        // Code to execute if none of the cases match
}

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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");        }    }}

Output

Wednesday

The switch statement checks the value of the day variable and matches it to the appropriate case. If no case matches, the default block is executed.

Flow Control in Java

Sequential Flow (Basic)

Decision-Making Statements

Java Tutorial

Python Tutorial