learning java 4th edition

This article mainly summarizes the knowledge points in Java containers, including the container hierarchy, class graph structure, and collection Interface Details, and a collection sub-interface list Interface related knowledge point summary. It involves learning and summarizing the underlying data structures, implementation mechanisms, and usage of some classes such as arraylist, javaslist, vector, stack,

employeenull If the hashCode() method is correctly overwritten, you will see the second line first employee instead of null , because the two objects are the same as the result of the equals() method comparison, according to rule 2 above: If two objects are the same as the results of the equals() method comparison, Then the two object calls hashCode() should return the same integer value.Q: How to properly overwrite hashCode() ?Answer: Joshua Bloch's "Effective

Before learning the new features of Java8, we briefly looked at the new features of the previous editions from Java5, which were summed up by others.New features of Java5, Java6, Java7, Java8http://blog.csdn.net/samjustin1/article/details/52268004Where Java 7 4th introduced System.getjavaiotempdir () .... These methods are no longer available, with system.getprop

referenced by external, then the key can be GC recycling, hum, know "garbage collection mechanism" of the bad bar.4, TreeMapIf you want to traverse the map by nature or by your own sort, find treemap, because the element you add to the SortedMap implementation class must implement the comparable interface, otherwise you must give its constructor an implementation of the comparator interface. The TreeMap class is the only implementation of SORTEDMAP. Here with a small section of code to let ever

superclass will be executed.Because the end method chain does not execute automatically, we need to ensure this manually.Method One: Use the TRY–FINALIZE code structure@Overrideprotected void Finalize () throws Throwable {try{.....//finalize Subclass State} finally {Super.finalize ();}}Method Two: Use Finalizer Guardian (end method Guardian)Class A {End GuardianPrivate Final Object Finalizerguardian = new Object () {@OverrideThe end method of the end Guardian will be executedprotected void Fina

A. A-round target Review the basics of network programming, focus on learning the TCP three handshake four waves, and possible anomalies. Recalling Socket programming, for many years did not write (Chao) over the relevant code. Re-learning NIO, previously learned the basic forgotten, after all, has never been used in the project. Learn Netty, learn basic usage, write a simple project pr

cross-platform development and can run on various platforms supported by Java. Of course, it is only for study and use, and cannot be used as a commercial purpose. Based on the Linux (Ubuntu 12.04) system, the author uses IDE NetBeans for development and contributes to various programmers in the form of open source code, it currently implements basic functions such as login and chat, and is currently in the stage of Interface Optimization and perform

, ActiveX now has the ability to use across platforms. In fact, ActiveX means "If your program is connected to its working environment, it can go to the Web page and run in an ActiveX-enabled browser" (IE solidifies support for ActiveX, and Netscape needs a plugin). So, ActiveX does not restrict our use of a particular language. For example, let's say we're already an experienced Windows programmer who can skillfully use languages like C + +, Visual Basic, or Borlanddelphi to create ActiveX almo

Java study note 12 --- parent class Object Reference pointing to Child class object, learning Note 12 --- What happens when the object reference of the parent class does not point to the object of the parent class, but to the object of the subclass? Assume that the parent class is Person and the subclass is Student. The following two rows are defined: Student sTest = new Student (); Person pTest = sTest; PT

About ServletA servlet is a small program that runs on a web container. This program is implemented using the Java programming language. On servers with large traffic, the advantage of Servlets is that they execute faster than CGI programs, and individual user requests are activated as one thread in a single program without creating a separate process, which means that the overhead of server-side processing requests is significantly reduced.Servlet li

client{public static void Main (string[] args) throws Exception {Socket socket = new socket ("localhost", 9999);Sending information to the serverOutputStream OS = Socket.getoutputstream ();PrintStream PS = new PrintStream (OS);PS.PRINTLN ("Client-side services");Read the information sent by the serverInputStream is = Socket.getinputstream ();BufferedReader br = new BufferedReader (new InputStreamReader (IS));String str = br.readline ();System.out.println (str);Br.close ();Is.close ();Socket.clo

; } public void setT(T t) { this.t = t; }}Type parameter naming conventions by convention, the name of the type parameter is made up of an uppercase letter. E-element element (used extensively by the Java collections Framework)K-key KeyN-number valueT-type typeV-value valueS,u,v etc.-2nd, 3rd, 4th types Second, third, fourth type Invoking and instantiating generic classesTo obtain a reference

Recently began to learn Java, work to read often sleepy, sometimes think of a very important point of knowledge to remember where and afraid to forget, then suddenly thought of the blog park, so this morning decided to remember in the yard, First write 8 is because already saw the eighth chapter (read Java Programming thought Fourth edition Complete Chinese, also

JDK API Documentation Java SE 8 API documentation:Http://www.oracle.com/technetwork/java/javase/documentation/jdk8-doc-downloads-2133158.htmlJdk-8-apidocs Online version:Http://docs.oracle.com/javase/8/docs/api/index.htmlJava SE 7 API documentation:Http://www.oracle.com/technetwork/java/javase/documentation/java-

, removes the last element from the container in the method body and joins the consumer. Examples of use are: carcontainerIf you have another setThe method Pop (setOur idea is that the pop receives the parameter application is "E of some kind of superclass set", through the "and Super keyword combined use just can achieve this purpose, namely setThird edition public void pop (setAfter the modification, setWith the use of the extends or Super

in collections, because elements are stored in the collection) T-type (Java Class) K-key (Key) V-value (value) N-number (numeric type) S, U, v-2nd, 3rd, 4th types 3. when using this class, we can write:1 New Box(); 2 b.setobj ("AAA"); 3 // // Compile error 4 String s = b.getobj ();4. use multiple type parameters:As we should have noticed when using map, Map uses generics to set t

example, If you read three bytes from a channel into a buffer, the Buffer's position will be set to 3, pointing to the 4th element in the Array. conversely, when you get data from a buffer to write a channel, it indicates that the next data is from the Array'sWhich Element. For example, When you write 5 bytes from a buffer into a channel, the Buffer's position is set to 5, which points to the sixth element of the Array. Mark a temporary storage locat

length 4 4 // Access array elements by subscript 4 5 6}The error message that is indicated in the run result is an array out-of-bounds exception arrayindexoutofboundsexception, the reason for this exception is that the length of the array is 4 and its index range is 0~ 3, while the 4th line of code in the preceding code uses the index 4来 to access the element beyond the array's index range.2. Two-dimensional arrayMultidimensional arrays ca

property in addition to the Set/set keyword at the time of definition. You can also add properties dynamically through the Object.defineproperty () function at run time, and provide finer control.The code is as follows (none of the following code is experimental):var o = {};Object.defineproperty (o, ' propname ', {The value of the value:1,//property can also be set by means of get:function () {Retun x;}Whether the writeable:true,//can be o.propname = newvalue; method to set the value of the pro

garbage value of each region, that is, the amount of space and time it takes to reclaim the region, and then maintains a priority queue, recovering one of the most valuable region per time, based on the allowable collection times.To avoid the garbage collection problems caused by the cross-referencing of each region, each region of G1 has a remembered Set that stores references to other region's objects in this region. When a memory is reclaimed, this part is also added when enumerating GC root