Conditionals

Conditionals in Java are used to make decisions based on certain conditions. They allow the program to execute different blocks of code based on whether a condition is true or false. In this tutorial, we will learn about conditionals in Java.

if Statement

The if statement is used to execute a block of code only if a specified condition is true. If the condition is false, the code block is skipped. The basic syntax of the if statement is as follows:

if (condition) {
    // code block to be executed if the condition is true
}

Here is an example of using the if statement:

int x = 10;

if (x > 5) {
    System.out.println("x is greater than 5");
}

// Output: x is greater than 5

In the above example, the code block inside the if statement is executed because the condition x > 5 is true.

if-else Statement

The if-else statement is used to execute one block of code if a specified condition is true and another block of code if the condition is false. The basic syntax of the if-else statement is as follows:

if (condition) {
    // code block to be executed if the condition is true
} else {
    // code block to be executed if the condition is false
}

Here is an example of using the if-else statement:

int x = 3;

if (x > 5) {
    System.out.println("x is greater than 5");
} else {
    System.out.println("x is less than or equal to 5");
}

// Output: x is less than or equal to 5

In the above example, the code block inside the if statement is skipped because the condition x > 5 is false, and the code block inside the else statement is executed.

if-else if-else Statement

The if-else if-else statement is used to execute one block of code if a specified condition is true, another block of code if a different condition is true, and a default block of code if none of the conditions are true. The basic syntax of the if-else if-else statement is as follows:

if (condition1) {
    // code block to be executed if condition1 is true
} else if (condition2) {
    // code block to be executed if condition2 is true
} else {
    // code block to be executed if none of the conditions are true
}

Here is an example of using the if-else if-else statement:

int x = 3;

if (x > 5) {
    System.out.println("x is greater than 5");
} else if (x < 5) {
    System.out.println("x is less than 5");
} else {
    System.out.println("x is equal to 5");
}

In the above example, the code block inside the else if statement is executed because the condition x < 5 is true.

Nested if Statements

Nested if statements are if statements inside another if statement. They are used to test multiple conditions in sequence. The inner if statement is executed only if the outer if statement’s condition is true. Here is an example of nested if statements:

int x = 10;
int y = 20;

if (x == 10) {
    if (y == 20) {
        System.out.println("x is 10 and y is 20");
    }
}

In the above example, the code block inside the inner if statement is executed only if both conditions x == 10 and y == 20 are true.

Ternary Operator

The ternary operator ? : is a shorthand way of writing an if-else statement. It is used to assign a value to a variable based on a condition. The basic syntax of the ternary operator is as follows:

variable = (condition) ? value1 : value2;

Here is an example of using the ternary operator:

int x = 10;
int result = (x > 5) ? 1 : 0;

System.out.println(result);

// Output: 1

In the above example, the value of result is assigned 1 if the condition x > 5 is true, and 0 otherwise.

Switch Statement

The switch statement is used to execute different blocks of code based on the value of an expression. It is an alternative to using multiple if-else if-else statements. The basic syntax of the switch statement is as follows:

switch (expression) {
    case value1:
        // code block to be executed if expression equals value1
        break;
    case value2:
        // code block to be executed if expression equals value2
        break;
    ...
    default:
        // code block to be executed if none of the values match
}

Here is an example of using the switch statement:

int day = 3;
String dayName;

switch (day) {
    case 1:
        dayName = "Monday";
        break;
    case 2:
        dayName = "Tuesday";
        break;
    case 3:
        dayName = "Wednesday";
        break;
    default:
        dayName = "Invalid day";
}

System.out.println("Day: " + dayName);

// Output: Day: Wednesday

In the above example, the value of dayName is assigned based on the value of the day variable using the switch statement.