Java Conditionals

Conditionals take an expression, which is code that evaluates to determine a value, and checks if it is true or false. If it’s true, we can tell our program to do one thing — we can even account for false to do another.

As we write more complex programs, conditionals allow us to address multiple scenarios and make our programs more robust.

If Statement

An if statement executes a block of code when a specified boolean expression is evaluated as true; otherwise, the block of code will be skipped.

if (berries > 5) {
  System.out.println("More than a handful of berries.");
}

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Else

An else clause can be added to an if statement.

The else statement executes a block of code when the condition inside the if statement is false:

• If the condition evaluates to true, code in the if part is executed.
• If the condition evaluates to false, code in the else part is executed.

The else statement is always the last condition.

if (year == 2022) {
  System.out.println("Print if year is 2022");
}
else {
  System.out.println("Print if year is not 2022");
}

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Else If

else if statements can be chained together to check multiple conditions. Once a condition is true, a code block will be executed and the conditional statement will be exited.

There can be multiple else if statements in a single conditional statement.

int testScore = 76;
char grade;

if (testScore >= 90) {
  grade = 'A';
} else if (testScore >= 80) {
  grade = 'B';
} else if (testScore >= 70) {
  grade = 'C';
} else if (testScore >= 60) {
  grade = 'D';
} else {
  grade = 'F';
}

System.out.println("Grade is " + grade);
// Output: Grade is C

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Nested Conditional Statements

A nested conditional statement is a conditional statement nested inside another conditional statement. The outer conditional statement is evaluated first; if the condition is true, then the nested conditional statement will be evaluated.

boolean studied = true;
boolean wellRested = true;

if (wellRested) {
  System.out.println("Best of luck today!");
  if (studied) {
    System.out.println("You are prepared for your exam!");
  } else {
    System.out.println("Study before your exam!");
  }
}

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The output would be:

Output: Best of luck today!
Output: You are prepared for your exam!

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Ternary Operator

The ternary operator (? :) is a shorthand way to write simple if-else statements. It evaluates a condition and returns one value if the condition is true and another if it is false. It follows the syntax:

condition ? expression_if_true : expression_if_false;

• Condition: An expression that evaluates to true or false.
• Expression if true: The value returned if the condition is true.
• Expression if false: The value returned if the condition is false.

public class Main {
    public static void main(String[] args) {
        int age = 18;
        String message = (age >= 18) ? "You are an adult." : "You are a minor.";
        System.out.println(message);
    }
}

// Output: You are an adult.

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