Java Reference
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from being called by passing false to writableStackTrace . Pass false to
writableStackTrace whenyouplantooverridethedefaultstacktraceandwantto
avoidtheunnecessary fillInStackTrace() methodcalls.Similarly,pass false
to enableSuppression whenrepeatedlycatchingandrethrowingthesameexcep-
exceptional circumstances.
You will notice that Throwable(String message, Throwable cause,
boolean enableSuppression, boolean writableStackTrace) issig-
nifiedasa protected constructor.Also,itsJavadocumentationincludesthefollow-
ingsentence:“Subclassesof Throwable shoulddocumentanyconditionsunderwhich
in Chapter 2 .
Moving down the throwable hierarchy, you encounter the
java.lang.Exception and java.lang.Error classes,whichrespectivelyrep-
resent exceptions and errors. Each class offers five constructors that pass their argu-
mentstotheir Throwable counterparts,butprovidesnomethodsapartfromthosethat
are inherited from Throwable .
Exception is itself subclassed by
java.lang.CloneNotSupportedException (discussed in Chapter 2 ) , (discussedin Chapter8 ) ,andotherclasses.Similarly, Er-
ror is itself subclassed by java.lang.AssertionError (discussed later in this
chapter), java.lang.OutOfMemoryError , and other classes.
Caution everinstantiate Throwable , Exception ,or Error .Theresultingob-
jects are meaningless because they are too generic.
Checked Exceptions Versus Runtime Exceptions
A checked exception isanexceptionthatrepresentsaproblemwiththepossibilityofre-
(examines) the code to ensure that the exception is handled in the method where it is
thrown, or is explicitly identified as being handled elsewhere.
Exception and all subclasses except for java.lang.RuntimeException
(and its subclasses) describe checked exceptions. For example, the CloneNotSup-
portedException and IOException classes describe checked exceptions.
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