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Comparison of Java and Android API
open-in-new
<h2 id="system-properties">System properties</h2> <p>As is the case for the <a href="/facts/Java_SE/1HMPhdsv">Java SE</a> class <a href="https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/lang/System.html">System</a>, the Android <a href="https://developer.android.com/reference/java/lang/System.html">System</a> class allows retrieving system properties. However, some mandatory properties defined with the Java virtual machine have no meaning or a different meaning on Android. For example: </p> <ul><li>java.version property returns 0 because it is not used on Android.</li> <li>java.specification.version invariably returns 0.9 independently of the version of Android used.</li> <li>java.class.version invariably returns 50 independently of the version of Android used.</li> <li>user.dir has a different meaning on Android.</li> <li>user.home and user.name properties do not exist on Android.</li></ul> <h2 id="class-library">Class library</h2> <p>Current versions of Android use the latest Java language and its libraries (but not full <a href="/facts/Graphical_user_interface/wBlQFWDP">graphical user interface</a> (GUI) frameworks), not the <a href="/facts/Apache_Harmony/wNJJJxVT">Apache Harmony</a> Java implementation, that older versions used. <a href="/facts/Java_8/Br6eHSP8">Java 8</a> source code that works in latest version of Android, can be made to work in older versions of Android.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p> <h3>java.lang package</h3> <p>By default, the default output stream <a href="https://developer.android.com/reference/java/lang/System.html#out">System.out</a> and <a href="https://developer.android.com/reference/java/lang/System.html#err">System.err</a> do not output anything,<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> and developers are encouraged to use the <a href="https://developer.android.com/reference/android/util/Log.html">Log</a> class, which logs Strings on the LogCat tool.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> This has changed at least from <a href="/facts/Android_Honeycomb/xIEao15x">HoneyComb</a>, and they now output to the log console also. </p> <h3>Graphics and widget library</h3> <p>Android does not use the <a href="/facts/Abstract_Window_Toolkit/QWTMvGHk">Abstract Window Toolkit</a> nor the <a href="/facts/Swing_(Java)/xFbyDcjS">Swing</a> library. <a href="/facts/User_interface/e9sPEWVD">User interfaces</a> are built using View objects. Android uses a framework similar to Swing, based on <a href="https://developer.android.com/reference/android/view/View.html">View</a>s rather than <a href="https://docs.oracle.com/en/java/javase/19/docs/api/java.desktop/javax/swing/JComponent.html">JComponent</a>s. However, Android widgets are not <a href="/facts/JavaBean/C0HvUnQ5">JavaBeans</a>: the Android application <a href="https://developer.android.com/reference/android/content/Context.html">Context</a> must be provided to the widget at creation. </p> <h4>Look and feel</h4> <p>Android widget library does not support a <a href="/facts/Pluggable_look_and_feel/MRbS5w2V">pluggable look and feel</a> architecture. The look and feel of Android widgets must be embedded in the widgets. However, a limited ability exists to set styles and themes for an application.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h4>Layout manager</h4> <p>Contrary to Swing where <a href="/facts/Layout_manager/QhYTMtcU">layout managers</a> can be applied to any <a href="/facts/Container_(abstract_data_type)/gsC5UcqD">container widget</a>, Android layout behavior is encoded in the containers.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> <h3>java.beans package</h3> <p>Android includes only a small subset of the java.beans package (<a href="https://developer.android.com/reference/java/beans/PropertyChangeEvent.html">PropertyChangeEvent</a> and related classes). </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Android_(operating_system)/nNyHb0xz">Android (operating system)</a></li> <li><a href="/facts/Java_(programming_language)/9ScgFyAL">Java (programming language)</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Rose, John (2008-05-31). "with Android and Dalvik at Google I/O". Archived from the original on 2008-06-04. Retrieved 2008-06-08. <a href="https://web.archive.org/web/20080604070631/http://blogs.sun.com/jrose/entry/with_android_and_dalvik_at" target="_blank">https://web.archive.org/web/20080604070631/http://blogs.sun.com/jrose/entry/with_android_and_dalvik_at</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Fred Chung (2011-07-28). "Custom Class Loading in Dalvik". Google. Archived from the original on 2014-02-18. Retrieved 2011-11-27. <a href="https://web.archive.org/web/20140218204452/http://android-developers.blogspot.com/2011/07/custom-class-loading-in-dalvik.html" target="_blank">https://web.archive.org/web/20140218204452/http://android-developers.blogspot.com/2011/07/custom-class-loading-in-dalvik.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Use Java 8 language features and APIs". Android Developers. Retrieved 2021-01-23. <a href="https://developer.android.com/studio/write/java8-support" target="_blank">https://developer.android.com/studio/write/java8-support</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"Android Debug Bridge". Google. Retrieved 2009-05-31. By default, the Android system sends stdout and stderr (System.out and System.err) output to /dev/null. <a href="https://developer.android.com/guide/developing/tools/adb.html" target="_blank">https://developer.android.com/guide/developing/tools/adb.html</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"Reading and Writing Logs". Google. Archived from the original on 2011-11-22. Retrieved 2011-11-27. <a href="https://web.archive.org/web/20111122031803/http://developer.android.com/guide/developing/debugging/debugging-log.html" target="_blank">https://web.archive.org/web/20111122031803/http://developer.android.com/guide/developing/debugging/debugging-log.html</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"Applying Styles and Themes". Google. Archived from the original on 2014-03-28. Retrieved 2011-09-03. <a href="https://web.archive.org/web/20140328224922/http://developer.android.com/guide/topics/ui/themes.html#ApplyAStyle" target="_blank">https://web.archive.org/web/20140328224922/http://developer.android.com/guide/topics/ui/themes.html#ApplyAStyle</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"Common Layout Objects". Google. Retrieved 2011-09-03. <a href="https://developer.android.com/guide/topics/ui/layout-objects.html" target="_blank">https://developer.android.com/guide/topics/ui/layout-objects.html</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> </ol>