What is the function of the " | " operator within the catch?

Question

I read that || (OR) is for boolean operations and | (Bitwise Operation) for bit operations. What is your function within a catch with multiple exceptions, then? I mean, I know it eliminates duplicate code but I’ve always considered it as a boolean OR.

Example

catch (IOException|SQLException ex) {
    logger.log(ex);
    throw ex;
}

If there is any IOException OR SQLException the loop is executed.

Answer 1

This is a Feature that was introduced from Java 7. You can use it to remove possible duplicate catch snippets. Ex:

catch (IOException ex) {
     logger.log(ex);
     throw ex;
} catch (SQLException ex) {
     logger.log(ex);
     throw ex;
}

for:

catch (IOException | SQLException ex) {
    logger.log(ex);
    throw ex;
}

You can see a full explanation on this link

Answer 2

In java SE 7 or higher a single block of catch can handle more than one type of exception, for this you must specify the types of exception you want to capture and separate them by a pipe |, example:

try {
    ...
}
catch (IOException|SQLException ex) {
    logger.log(ex);
    throw ex;
}

In this case the pipe is not a logical operator but a syntax of the resource.

In previous versions of Java we had to treat the exceptions individually or use a more comprehensive class (Exception, for example) to capture launches of all possible exceptions, with this feature we can transform, for example:

This code

try {
    System.out.println(10 / 0);
} catch (ArithmeticException e) {
    System.out.println("Erro: " + e.getMessage());
} catch (IllegalArgumentException e) {
    System.out.println("Erro: " + e.getMessage());
} catch (ArrayIndexOutOfBoundsException e) {
    System.out.println("Erro: " + e.getMessage());
}

In this

try {
    System.out.println(10 / 0);
} catch (ArithmeticException | IllegalArgumentException | ArrayIndexOutOfBoundsException e) {
    System.out.println("Erro: " + e.getMessage());
}

OBS: The variable declared in catch is always final, that is, we cannot assign any value to it.

Source: Oracle

Answer 3

The symbol serves exactly for what you have guessed, it is like an "OR". It serves for you to capture multiple exceptions in a single block catch, instead of making a catch for every exception. For example, this:

try {
  // Código a executar
} catch (ExceptionType1 name) {
  // Código a executar quando uma exceção do tipo "ExceptionType1" for disparada
} catch (ExceptionType2 name) {
  // Código a executar quando uma exceção do tipo "ExceptionType2" for disparada
}

Can be reduced to this:

try {
  // Código a executar
} catch (ExceptionType1|ExceptionType2 name) {
  // Código a executar quando uma exceção do tipo "ExceptionType1" ou "ExceptionType2" for disparada
}

But why not use the "||"?

If we analyze, the | and the || has the same function: to check multiple conditions at once ("if condição1 for X or condição2 for Y or condição3 for Z", etc). But there is a small difference. The || is a logical operator, as has already been said, we check various conditions in a conditional structure. But the code within the catch nay is a condition, therefore, the || does not take the role of "or conditional".

Reference

• https://docs.oracle.com/javase/tutorial/essential/exceptions/catch.html
• https://docs.oracle.com/javase/8/docs/technotes/guides/language/catch-multiple.html

Answer 4

Good afternoon, I don’t have much experience, but I think you could put two catch... in SQL what do you want to do? It would be the connection?

catch (IOException ex1) {
    logger.log(ex);
    throw ex;
}
catch (SQLException e) {
    System.out.println("Erro ao Conectar ", e.getMessage());
}