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% Document Info
\author{Huluvu424242 (FunThomas424242)}
\pdfinfo{
  /Title (java-memory-model.pdf)
  /Creator (Cheatography)
  /Author (Huluvu424242 (FunThomas424242))
  /Subject (Java Memory Model Cheat Sheet)
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    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Java Memory Model Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{Huluvu424242 (FunThomas424242)} via \textcolor{DarkBackground}{\uline{cheatography.com/19991/cs/3927/}}}
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  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}Huluvu424242 (FunThomas424242) \\
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        \uline{\seqsplit{github}.com/Huluvu424242}
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 11th May, 2016.\\
   Page {\thepage} of \pageref{LastPage}.
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  Measure your website readability!\\
  www.readability-score.com
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\begin{document}
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% www.emerson.emory.edu/services/latex/latex_169.html
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\begin{tabularx}{17.67cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{17.67cm}}{\bf\textcolor{white}{Volatile Variablen}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{17.67cm}}{1. Vor jeder Auswertung der Variable (Laden) wird ihr aktueller Wert aus dem Hauptspeicher in den lokalen Thread Speicher geholt (gelesen).} \tn 
% Row Count 3 (+ 3)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{17.67cm}}{2. Nach jeder Zuweisung (Speichern) wird ihr aktueller Wert aus dem lokalen Thread Speicher in den Hauptspeicher geschrieben.} \tn 
% Row Count 6 (+ 3)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{17.67cm}}{3. Volatile Variablen werden in genau der Reihenfolge geschrieben oder gelesen wie vom Thread angefordert.} \tn 
% Row Count 9 (+ 3)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{17.67cm}}{4. Die Lese- und Schreibzugriffe sind immer atomar (auch bei double und long -64 bit Werten- bei denen das sonst nicht so ist).} \tn 
% Row Count 12 (+ 3)
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\par\addvspace{1.3em}

\begin{tabularx}{17.67cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{17.67cm}}{\bf\textcolor{white}{Singleton - unsichere Initialisierung}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{17.67cm}}{Diese Implementierung hat folgende Besonderheiten: \newline {[}1{]} Theoretisch funktioniert sie nicht - in der Praxis taugt sie aber als Signleton (siehe dazu folgende \{\{popup="http://www.bibsonomy.org/bibtex/20c33818a5d629b8f3fd9d4382334219f/funthomas424242"\}\}Diskussion\{\{/popup\}\}) \newline {[}2{]} Man darf sich hier bei Zugriff nicht auf ein korrekt initialisiertes Signleton verlassen, da im konkreten Fall auf Grund des Memory Modelles keine Annahmen darüber zugelassen sind wann die Felder des erzeugten Singleton wirklich alle korrekt befüllt und für jeden Thread konsistent lesbar sind. \newline  \newline public class Resource\{ \newline  private static Resource singleton; \newline public static Resource createInstance()\{ \newline    if(singleton==null)\{                                  //erster Test \newline     synchronized(Resource.class)\{ \newline       if(singleton==null)\{                              //zweiter Test \newline          singleton=new Resource(); \newline       \} //endif \newline      \} // end sync \newline    \}// endif \newline  return singleton;  \newline  \} \newline \}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\mymulticolumn{1}{x{17.67cm}}{Details zum Problem unter: http://www.cs.umd.edu/\textasciitilde{}pugh/java/memoryModel/DoubleCheckedLocking.html}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\par\addvspace{1.3em}

\begin{tabularx}{17.67cm}{X}
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\mymulticolumn{1}{x{17.67cm}}{\bf\textcolor{white}{Singleton - korrekte Intialisierung}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{17.67cm}}{private static volatile Resource resource; \newline private static volatile Resource singleton; \newline public static Resource createInstance()\{ \newline  if(resource==null)\{ \newline   synchronized(Resource.class)\{ \newline    if(singleton==null)\{ \newline        singleton=new Resource(); \newline    \} \newline   \} \newline   resource=singleton; \newline  \} \newline  return resource; \newline \}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{17.67cm}}{Ähnliche L{\"o}sungen werden auch hier diskutiert: \seqsplit{http://www.angelikalanger.com/Articles/EffectiveJava/41.JMM-DoubleCheck/41.JMM-DoubleCheck.html}}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\par\addvspace{1.3em}



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