Flash cards
Review the key moves
What is the main idea behind Java throw Keyword?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
public ___ Main {Put the learning moves in the order that makes the concept easiest to apply.
❮ Java Keywords
Example
public class Main {
static void checkAge(int age) {
if (age < 18) {
throw
new ArithmeticException("Access denied - You must be at least 18 years old.");
}
else {
System.out.println("Access granted - You are old enough!");
}
}
public static void main(String[] args) {
checkAge(15); // Set age to 15 (which is below 18...)
}
}Definition and Usage
The throw keyword is used to create a custom error.
The throw statement is used together with an exception type . There are many exception types available in Java: ArithmeticException , ClassNotFoundException , ArrayIndexOutOfBoundsException , SecurityException , etc.
The exception type is often used together with a custom method , like in the example above.
Differences between throw and throws
| throw | throws |
|---|---|
| Used to throw an exception for a method | Used to indicate what exception type may be thrown by a method |
| Cannot throw multiple exceptions | Can declare multiple exceptions |
| Syntax: throw is followed by an object (new type ) used inside the method | Syntax: throws is followed by a class and used with the method signature |
- throw is followed by an object (new type )
- used inside the method
- throws is followed by a class
- and used with the method signature
Related Pages
Read more about exceptions in our Java Try..Catch Tutorial .
❮ Java Keywords