A collection of helper methods for dealing with exceptions in Java 8.
The scope of Fishbowl is divided into four sections.
There are two options if a statement inside of a method (may) throw a
checked exception that cannot be handled reasonably. The exception can be
rethrown and the caller of the current method has to handle it or it can
be wrapped with a RuntimeException. Use Fishbowl's method
wrapCheckedException for doing this with a single line of
code.
public void doSomething(InputStream is) {
//originally both lines can throw an IOException
int nextByte = wrapCheckedException(() -> is.read());
wrapCheckedException(() -> is.close());
}Sometimes exceptions are best handled by returning a default
value. This can be done by a single line of code with
defaultIfException.
public void doSomething() {
long value = defaultIfException(() -> parseLong("NaN"),
NumberFormatException.class, 0L);
//value is 0
}Sometimes it is appropriate to continue if a void method fails. This can be easily done with ignoreException.
public void doSomething() {
MyWorker worker = new MyWorker();
ignoreException(() -> worker.doSomethingThatThrowsAnException());
//the following statement is executed even if worker throws an
//exception.
doSomethingElse();
}Fishbowl makes it possible to use the AAA (Arrange-Act-Assert) pattern for writing tests for code that throws an exception. For that purpose it exposes the exception so that it can be checked by any assertion library.
@Test
public void anExceptionIsThrown() {
String noString = null;
Throwable exception = exceptionThrownBy(() -> noString.trim());
assertEquals(NullPointerException.class, exception.getClass());
}