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RuntimeException

RuntimeExceptions do not require try/catch blocks in the code. They can usually be avoided with proper care when coding. However, when mistakes are not detected and the RuntimeException is uncaught, it will cause the application to fail and display issue information that the user may not always understand. In this exercise, you will see what happens when you don't catch a possible RuntimeException and what happens when you do try/catch them.

Este exercício faz parte do curso

Data Types and Exceptions in Java

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Instruções do exercício

  • Examine the withoutTryCatch() and withTryCatch methods in this application and note difference between them.
  • Run the application without changes - which results in the withoutTryCatch() method to execute that causes a RuntimeException.
  • Comment out line 5 and uncomment line 7, and then rerun the application - which results in the withTryCatch() method executing which this time handles the RuntimeException.

Exercício interativo prático

Experimente este exercício completando este código de exemplo.

public class RuntimeExceptionHandling {

	public static void main(String[] args) {
		// Comment out this line
		withoutTryCatch();
		// Uncomment this line
		// withTryCatch();
	}

	public static void withoutTryCatch() {
		String[] mounts = { "Everest", "K2", "Kangchenjunga", "Lhotse" };
		String selectedMount = mounts[4];
		System.out.println("Selected item is: " + selectedMount);
	}

	public static void withTryCatch() {
		try {
			String[] mounts = { "Everest", "K2", "Kangchenjunga", "Lhotse" };
			String selectedMount = mounts[4];
			System.out.println("Selected item is: " + selectedMount);
		} catch (ArrayIndexOutOfBoundsException e) {
			System.out.println("Oops - made a mistake accessing the mounts array with a bad index.");
		}
	}
}
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