Else If

If you have an if nested in an else branch, you can simplify that by using else if.

boolean cool = true; // 🕶️
int age = 30; // 🙎‍♀️
if (age < 25) {
    System.out.println("You cannot rent a car!");
}
else {
    if (!cool) {
        System.out.println("You failed the vibe check.");
    }
    else {
        System.out.println("You are rad enough to rent a car.");
    }
}

So the following will work the same as the code above.

boolean cool = true; // 🕶️
int age = 30; // 🙎‍♀️

if (age < 25) {
    System.out.println("You cannot rent a car!");
}
else if (!cool) {
    System.out.println("You failed the vibe check.");
}
else {
    System.out.println("You are rad enough to rent a car.");
}

You can have as many else ifs as you need. Each one will only run if all the previous conditions evaluate to false.

boolean cool = true; // 🕶️
int age = 100; // 👴

if (age < 25) {
    System.out.println("You cannot rent a car!");
}
else if (!cool) {
    System.out.println("You failed the vibe check.");
}
else if (age > 99) {
    System.out.println("You are too old to safely drive a car!");
}
else if (age > 450) {
    System.out.println("There can only be one! ⚔️🏴󠁧󠁢󠁳󠁣󠁴󠁿");
}
else {
    System.out.println("You are rad enough to rent a car.");
}