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| Beide Seiten der vorigen Revision Vorhergehende Überarbeitung Nächste Überarbeitung | Vorhergehende Überarbeitung | ||
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becki:linux:java [2009-04-28 10:10] becki |
becki:linux:java [2010-10-19 12:50] (aktuell) becki |
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| ====== Java == | ====== Java == | ||
| - | ===== Links == | + | ===== Related Pages == |
| - | [[sunkurs]] | [[comparison table]] | + | <pagelist> |
| + | * [[java plumbing]] | ||
| + | * [[java web programming]] | ||
| + | * [[apache click]] | ||
| + | * [[apache tomcat]] | ||
| + | * [[jrunscript]] | ||
| + | </pagelist> | ||
| ===== Java Versions and Compatibility == | ===== Java Versions and Compatibility == | ||
| Zeile 78: | Zeile 84: | ||
| </code> | </code> | ||
| - | ===== Applets == | + | ===== Rich Internet Applications == |
| - | ==== Requirements == | + | |
| + | FIXME Whole secton is obsoete. See [[java plumbing]] instead! | ||
| + | |||
| + | ==== Java Web Start == | ||
| + | |||
| + | This might help: http://www.developer.com/java/web/article.php/3828811 | ||
| + | |||
| + | ==== Applets == | ||
| + | === Embedding in HTML == | ||
| + | |||
| + | Easiest is to use the [[javatut>uiswing/components/applet.html#plugin|applet tag]] | ||
| + | |||
| + | See also: | ||
| + | |||
| + | * [[http://www.developer.com/java/article.php/3841566/|Java ARchive (JAR) Files]] tutorial | ||
| + | * [[javaref>technotes/guides/plugin/developer_guide/using_tags.html|Using applet, object and embed Tags]] | ||
| + | * [[http://java.sun.com/products/plugin/versions.html|Encountering OBJECT, EMBED, and APPLET Tags With Different Plug-in Versions and Browsers]] | ||
| + | * The CODEBASE-attribute of the applet-tag has a different meaning of the CODEBASE-attribute of the object-tag! | ||
| + | * [[javaref>technotes/guides/plugin/developer_guide/java_js.html|Java-to-Javascript Communication]] (needs plugin.jar) | ||
| + | |||
| + | === Code Template == | ||
| + | |||
| + | It is [[javatut>deployment/applet/|recommended]] to use ''JAppled'' instead of ''Applet''. Therefore the rest of this section is obsolete. An example for the use of ''JAppled'' is provided [[java#deploy_both_as_applet_and_jws|below]]. | ||
| <code java> | <code java> | ||
| Zeile 95: | Zeile 123: | ||
| - inherited from java.awt.Container | - inherited from java.awt.Container | ||
| see also Java Tutorial Sun: Lesson: Overview of Applets | see also Java Tutorial Sun: Lesson: Overview of Applets | ||
| - | |||
| - | ==== Embedding in HTML == | ||
| - | |||
| - | see: | ||
| - | * [[javatut>uiswing/components/applet.html#plugin|Sun Java Tutorial -> Swing -> Applets]] and continuative links | ||
| - | * [[javaref>technotes/guides/plugin/developer_guide/using_tags.html|Using applet, object and embed Tags]] | ||
| - | * [[http://java.sun.com/products/plugin/versions.html|Encountering OBJECT, EMBED, and APPLET Tags With Different Plug-in Versions and Browsers]] | ||
| - | * The CODEBASE-attribute of the applet-tag has a different meaning of the CODEBASE-attribute of the object-tag! | ||
| - | * [[javaref>technotes/guides/plugin/developer_guide/java_js.html|Java-to-Javascript Communication]] (needs plugin.jar) | ||
| ===== Events == | ===== Events == | ||
| Zeile 166: | Zeile 185: | ||
| String s= ""+ 4711; | String s= ""+ 4711; | ||
| String s= new Integer(4711).toString(); | String s= new Integer(4711).toString(); | ||
| + | String s= String.valueOf(4711); | ||
| </code> | </code> | ||
| Zeile 265: | Zeile 285: | ||
| </code> | </code> | ||
| - | ===== Threads ====== | + | ===== Collections == |
| - | ==== Thread States ====== | + | ==== Overview == |
| + | |||
| + | [[javatut>reallybigindex.html#collections|Chapter in the Java tutorial]] | ||
| + | |||
| + | | //[[javaref>api/java/util/Collection.html|Collection]]// |||| //[[javaref>api/java/util/Map.html|Map]]// || | ||
| + | | //[[javaref>api/java/util/Set.html|Set]]// || //[[javaref>api/java/util/List.html|List]]// | //[[javaref>api/java/util/Queue.html|Queue]]// | || | ||
| + | | | //[[javaref>api/java/util/SortedSet.html|SortedSet]]// | | | | //[[javaref>api/java/util/SortedMap.html|SortedMap]]// | | ||
| + | | HashSet LinkedHashSet | TreeSet | LinkedList Vector ArrayList | LinkedList, PriorityQueue | HashTable LinkedHashMap HashMap | TreeMap | | ||
| + | |||
| + | ==== Implementations == | ||
| + | |||
| + | * [[javatut>collections/implementations/|Overview]] | ||
| + | * [[http://www.developer.com/java/article.php/3829891|Selecting the Best Java Collection Class for Your Application]] | ||
| + | * [[javatut>collections/implementations/map.html|General purpose map implementations]] | ||
| + | |||
| + | ==== Methods == | ||
| + | |||
| + | <code java> | ||
| + | // important methods of List: | ||
| + | boolean add(E e) | ||
| + | void add(int index, E element) | ||
| + | boolean contains(Object o) | ||
| + | E get(int index) | ||
| + | int indexOf(Object o) | ||
| + | Iterator<E> iterator() | ||
| + | E remove(int index) | ||
| + | boolean remove(Object o) // Removes the first occurrence | ||
| + | Object[] toArray() | ||
| + | <T> T[] toArray(T[] a) | ||
| + | |||
| + | // important methods of Map | ||
| + | boolean containsKey(Object key) | ||
| + | boolean containsValue(Object value) | ||
| + | V get(Object key) | ||
| + | Set<K> keySet() // Returns a set of the keys | ||
| + | V put(K key, V value) // there is no add! | ||
| + | V remove(Object key) | ||
| + | |||
| + | // important methods of Queue: | ||
| + | boolean offer(E o) // Inserts the specified element at the end; also add() possible | ||
| + | E peek() // Retrieves, but does not remove, | ||
| + | E poll() // Retrieves and removes from the beginning; remove() also possible | ||
| + | </code> | ||
| + | |||
| + | * Set: has no special order and no duplicates are permitted, not indexed; methods ar a subset of List (no index operations) | ||
| + | * List: ordered, duplicates are permitted, indexed | ||
| + | * Map does not implement the collection interface | ||
| + | * 'Sorted' is a subset of 'Ordered' | ||
| + | * Ordering: | ||
| + | * //Lists// are always ordered by index | ||
| + | * //Linked// collections are always ordered by insertion or last access | ||
| + | * //Tree// collections are always sorted | ||
| + | * List can made thread-save by Collections.synchronizedList() | ||
| + | * Tutorial: Vector is a legacy class; API: Vector is a normal class; Hashtable is similar; Vector also implements List | ||
| + | * HashSet & LinkedHashSet: Overwrite hashCode() so that equal objects provide the same hashcode | ||
| + | * LinkedList implements //List// and //Queue// | ||
| + | * //Queue// has Fifo (not stack) behaviour! | ||
| + | * All Interfaces have a size() method | ||
| + | * PriorityQueue sorts Elements by natural order using Comparable | ||
| + | * Elements for SortedSet/TreeSet, SortedMap/TreeMap | ||
| + | |||
| + | PriorityQueue must implement the Comparable interface! | ||
| + | * String implements interface Comparable<String> and Integer implements Comparable<Integer> -> Trying to add both Types to any untyped (old style) Tree-Container results in a ClassCastException | ||
| + | * Whereas adding only the same Type (eg Strings) works but gives a compiler warning. (I assume the type is detected at run time by reflection and the Object to compare is casted to String before compareTo() is called.) | ||
| + | |||
| + | ==== Sorting and Searching == | ||
| + | === Sorting with the Comparable Interface == | ||
| + | |||
| + | To sort a //List// (eg ArrayList) or an array use: | ||
| + | <code java> | ||
| + | static void Collections.sort(List<T> list); | ||
| + | static void Arrays.sort(allPrimitivesAndObject[] a); | ||
| + | </code> | ||
| + | The List interface has no sort method! All elements in the List or array must implement the Comparable interface: | ||
| + | |||
| + | <code java> | ||
| + | Interface Comparable<T> { | ||
| + | int compareTo(T o); | ||
| + | } | ||
| + | </code> | ||
| + | Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object. Keep in mind that compareTo accepts Type T (the generic of the List) wheras equals always only accepts type Object! | ||
| + | |||
| + | === Sorting with the Comparator Interface == | ||
| + | |||
| + | <code java> | ||
| + | static void Collections.sort(List<T> list, Comparator<? super T> c); | ||
| + | static void Arrays.sort(T[] a, Comparator<? super T> c); // T is an Object, no primitives! | ||
| + | |||
| + | Interface Comparator<T> { | ||
| + | int compare(T o1, T o2); | ||
| + | } | ||
| + | </code> | ||
| + | |||
| + | === Searching == | ||
| + | |||
| + | <code java> | ||
| + | static int Collections.binarySearch(List<T> list, T key[, Comparator<? super T> c]); | ||
| + | static int Arrays.binarySearch(allPrimitivesAndObject[] a, allPrimitivesAndObject key); | ||
| + | static int Arrays.binarySearch(T[] a, T key, Comparator<? super T> c); | ||
| + | </code> | ||
| + | Call binarySearch() with the array or List as first param, the key as second, and, if not all items implement the Comparable interface, provide a Comparator as 3rd parameter. List or array has to be sorted before binarySearch can be called, otherwise the result is not predictable! If the element is not found, binarySearch returns -length-1 | ||
| + | |||
| + | ===== Threads == | ||
| + | ==== Basics == | ||
| + | |||
| + | A thread owns the locks on one or more objects. The lock of an object can only have one thread as owner. | ||
| + | |||
| + | Only one thread can access the code in a syncronized method or code block at one time. ''syncronized'' refers always to an object, not to code; the lock is acquired per object. | ||
| + | |||
| + | ==== Thread States == | ||
| <code> | <code> | ||
| Zeile 275: | Zeile 404: | ||
| Verify: As a rule of thumb, only the current thread can bring itself from state Running to another state, other threads can't. | Verify: As a rule of thumb, only the current thread can bring itself from state Running to another state, other threads can't. | ||
| - | ==== Creating a Thread ====== | + | ==== Creating a Thread == |
| Two techniques for providing a run method for a thread: | Two techniques for providing a run method for a thread: | ||
| Zeile 376: | Zeile 505: | ||
| Got exception in HelloThread! | Got exception in HelloThread! | ||
| Good bye from SlaveThread! | Good bye from SlaveThread! | ||
| - | </code> | ||
| - | |||
| - | === Open ==== | ||
| - | |||
| - | <code java> | ||
| - | ThreadGroup getThreadGroup() // ? Returns the thread group to which this thread belongs. | ||
| - | isAlive() | ||
| </code> | </code> | ||
| Zeile 474: | Zeile 596: | ||
| ==== Misc == | ==== Misc == | ||
| + | * Possibly useful: [[ibm>java/library/j-javadev2-7.html|Kilim]] //actors// instead of threads for concurrent programming | ||
| * [[http://www.developer.com/design/article.php/3680701|Thread local static variables]] (Threads Versus The Singleton Pattern) | * [[http://www.developer.com/design/article.php/3680701|Thread local static variables]] (Threads Versus The Singleton Pattern) | ||
| * Possibly useful: Simple thread control with [[http://www.developer.com/java/article.php/3713031|CountDownLatch]] | * Possibly useful: Simple thread control with [[http://www.developer.com/java/article.php/3713031|CountDownLatch]] | ||
| Zeile 677: | Zeile 800: | ||
| t1.state= Tribool.State.FALSE; t0.state= Tribool.State.FALSE; | t1.state= Tribool.State.FALSE; t0.state= Tribool.State.FALSE; | ||
| System.out.println((t0.and(t1)).toString()); | System.out.println((t0.and(t1)).toString()); | ||
| - | |||
| } | } | ||
| } | } | ||
| </code> | </code> | ||
| - | ===== open questions / todo ====== | + | ===== Further Reading / 2do == |
| + | * Intro to the [[ibm>java/library/j-5things9.html|Java Scripting API]] with [[jrunscript]] | ||
| + | * Doc general Java strategy: Use [[Apache Pivot]] for the GUI, [[JUnit]] for testing, [[Apache Ant]] for building, JWS for distribution and [[Groovy]] for coding | ||
| + | * [[http://www.linux-magazin.de/Heft-Abo/Ausgaben/2008/08/Reiches-Angebot|Webentwicklung mit Java]]: An Overview (german) | ||
| + | * [[http://www.ibm.com/developerworks/opensource/library/os-lombok/|Eliminate Java verbosity with Lombok]] | ||
| + | * REST (with AJAX): | ||
| + | * Wink is a framework for building RESTful Web services | ||
| + | * [[ibm>web/library/wa-aj-jackson/|Wink with Jackson]], a [[http://jackson.codehaus.org/|Java JSON-processor]] | ||
| + | * [[ibm>web/library/wa-aj-richjava/|Build rich Java Web applications with Apache Wink and Ajax]] | ||
| + | * [[ibm>web/library/wa-apachewink1/|RESTful Web services with Apache Wink]] | ||
| + | * [[http://www.developer.com/article.php/3843846|JAX-RS]]: The Java API for RESTful Web Services | ||
| + | * [[http://www.developer.com/article.php/3841046|Real World REST]] using Jersey, AJAX and JSON | ||
| + | * [[http://www.developer.com/java/article.php/3837316/|Non-Blocking I/O Made Possible in Java]] | ||
| * Dick Wall [[http://www.developer.com/java/ent/print.php/10933_3813031_1|recommends]] to create a reusable genericized ''Pair'' (and ''Triple'') class (like in the C++ Standard Library) for the main purpose of being able to conveniently and typsave return more values at once from a method. | * Dick Wall [[http://www.developer.com/java/ent/print.php/10933_3813031_1|recommends]] to create a reusable genericized ''Pair'' (and ''Triple'') class (like in the C++ Standard Library) for the main purpose of being able to conveniently and typsave return more values at once from a method. | ||
| - | * Do I have to make classes final to optimize? see [[http://www.ibiblio.org/javafaq/javafaq.html#xtocid1902957]] | + | * [[http://www.developer.com/java/ent/print.php/3623781|Internationalization in Java]] using string resource referencesis better than ResourceBundle's (?) |
| + | * Do we have to make classes final to optimize? see [[http://www.ibiblio.org/javafaq/javafaq.html#xtocid1902957]] | ||
becki/linux/java.1240913445.txt.gz · Zuletzt geändert: 2009-04-28 10:10 von becki
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