簡単なGroovyテスト:
public class Instance {
List<String> runningThreads = new ArrayList<String>()
void test(boolean returnInFinally) {
println "\ntest(returnInFinally: $returnInFinally)"
println "--------------------------------------------------------------------------"
println "before execute"
String result = execute(returnInFinally, false)
println "after execute -> result: " + result
println "--------------------------------------------------------------------------"
println "before execute"
try {
result = execute(returnInFinally, true)
println "after execute -> result: " + result
} catch (Exception ex) {
println "execute threw exception: " + ex.getMessage()
}
println "--------------------------------------------------------------------------\n"
}
String execute(boolean returnInFinally, boolean throwError) {
String thread = Thread.currentThread().getName()
println "...execute(returnInFinally: $returnInFinally, throwError: $throwError) - thread: $thread"
runningThreads.add(thread)
try {
if (throwError) {
println "...error in execute, throw exception"
throw new Exception("as you liked :-)")
}
println "...return 'OK' from execute"
return "OK"
} finally {
println "...pass finally block"
if (returnInFinally) return "return value from FINALLY ^^"
// runningThreads.remove(thread)
}
}
}
Instance instance = new Instance()
instance.test(false)
instance.test(true)
出力:
test(returnInFinally: false)
-----------------------------------------------------------------------------
before execute
...execute(returnInFinally: false, throwError: false) - thread: Thread-116
...return 'OK' from execute
...pass finally block
after execute -> result: OK
-----------------------------------------------------------------------------
before execute
...execute(returnInFinally: false, throwError: true) - thread: Thread-116
...error in execute, throw exception
...pass finally block
execute threw exception: as you liked :-)
-----------------------------------------------------------------------------
test(returnInFinally: true)
-----------------------------------------------------------------------------
before execute
...execute(returnInFinally: true, throwError: false) - thread: Thread-116
...return 'OK' from execute
...pass finally block
after execute -> result: return value from FINALLY ^^
-----------------------------------------------------------------------------
before execute
...execute(returnInFinally: true, throwError: true) - thread: Thread-116
...error in execute, throw exception
...pass finally block
after execute -> result: return value from FINALLY ^^
-----------------------------------------------------------------------------
質問:
私にとって興味深い点の1つは、Groovyが暗黙のリターンを処理する方法を確認することでした。Groovyでは、メソッドから値を「返す」ことができます(戻り値なしで)値を最後に残すだけです。finallyステートメントのrunningThreads.remove(..)行のコメントを外すとどうなると思いますか?これは通常の戻り値( "OK")を上書きして例外をカバーしますか?!