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Exception – try catch

When an error occurs, Java will normally stop and generate an error message

The techinal term for this is : Java will throw an exception

try and catch

try statement

• allows you to define a code block to be tested for errors while is being executed

catch statement

• allows you to define a code block to be executed, if an error occurs in the try block

try and catch keywords come in pairs

finally statement

• lets you execute code, after try-catch, regardless of the result

public class Main {
	public static void main(String[] args){
		try {
			int[] myNumbers = {1,2,3};
			System.out.println(myNumbers[10]);
		} catch (Exception e) {
			System.out.println(“Something went wrong.”);
		} finally {
			System.out.println(“The \‘try catch\’ is finished.”);
		}
	}
}

The output will be

Something went wrong.
The ‘try catch’ is finished.

throw

Allows you to create a custom error

Is used together with an exception type

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!”);
		}
	}

if you call checkAge(15); in main method, the output will be

Exception in thread “main” java.lang.ArithmeticException : Access denied – You must be at least 18 years old.