Nested try blocks

Nested try blocks:

A try block can be placed inside another try block.
If an exception is not caught in the inner try block, it will be propagated to the outer try block.

Exception propagation:
When an exception occurs in the inner block and is not handled by it, it can be caught by the outer block, allowing the program to continue or terminate in a controlled manner.

Example code with nested try:
The following example shows an inner try block that handles division by zero errors, while the outer try block handles access exceptions outside the array boundaries.

Code example:

// Usa um bloco try aninhado.
class NestTrys {
    public static void main(String args[]) {
        // O array numer é mais longo que denom.
        int numer[] = { 4, 8, 16, 32, 64, 128, 256, 512 };
        int denom[] = { 2, 0, 4, 4, 0, 8 };

        try { // Bloco try externo
            for (int i = 0; i < numer.length; i++) {
                try { // Bloco try aninhado
                    // Tenta realizar a divisão
                    System.out.println(numer[i] + " / " + denom[i] + " is " + numer[i] / denom[i]);
                } catch (ArithmeticException exc) {
                    // Captura exceção de divisão por zero
                    System.out.println("Can't divide by Zero!");
                }
            }
        } catch (ArrayIndexOutOfBoundsException exc) {
            // Captura exceção de acesso fora dos limites do array
            System.out.println("No matching element found.");
            System.out.println("Fatal error - program terminated.");
        }
    }
}

Program output:
When division by zero occurs, the exception is caught by the internal try block and the program continues.
When an index error occurs outside the bounds of the array, the outer try block catches the exception and terminates the program.~

Example output:

4 / 2 is 2
Can't divide by Zero!
16 / 4 is 4
32 / 4 is 8
Can't divide by Zero!
128 / 8 is 16
No matching element found.
Fatal error – program terminated.

Practical use:

• Nested try blocks allow different types of errors to be handled separately:
• Lesser errors (such as division by zero) can be handled locally, allowing the program to continue.
• More serious errors (such as access outside the bounds of the array) can be caught by the external block, leading to a more drastic action, such as program termination.

Conclusion:

• Using nested try blocks is useful when different categories of errors need to be handled in different ways.
• This allows greater flexibility in controlling the program's execution flow, allowing you to handle mild exceptions internally and leaving severe exceptions for the external block.

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