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A comment (by user soc) on an answer to a question about tail call optimisation mentioned that Java 7 has a new feature called "suppressed exceptions", because of "the addition of ARM" (support for ARM CPUs?).
What is a "suppressed exception" in this context? In other contexts a "suppressed exception" would be an exception that was caught and then ignored (rarely a good idea); this is clearly something different.
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Programmers often suppress checked exceptions by catching exceptions with an empty or trivial catch block. Each catch block must ensure that the program continues only with valid invariants.
To ignore an exception in Java, you need to add the try... catch block to the code that can throw an exception, but you don't need to write anything inside the catch block.
The Throwable class is the superclass of all errors and exceptions in the Java language. Only objects that are instances of this class (or one of its subclasses) are thrown by the Java Virtual Machine or can be thrown by the Java throw statement.
To clarify the quote in Jon's answer, only one exception can be thrown by a method (per execution) but it is possible, in the case of a try-with-resources, for multiple exceptions to be thrown. For instance one might be thrown in the block and another might be thrown from the implicit finally provided by the try-with-resources.
The compiler has to determine which of these to "really" throw. It chooses to throw the exception raised in the explicit code (the code in the try block) rather than the one thrown by the implicit code (the finally block). Therefore the exception(s) thrown in the implicit block are suppressed (ignored). This only occurs in the case of multiple exceptions.
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