Java

When inheriting the method of implementing an interface, if the generic interface directly specifies the type without subsequent casts, this directly represents the type, and the parameter is the type Set the upper bound of a generic object to

ARead the example carefully : Enumtest.java , run it, analyze the running results? What conclusions can you get? Have you mastered the basic usage of enum types? Conclusion : The enumeration does not belong to the original data type, and each of its

This is the first piece of advice effective Java 2nd proposed: Consider replacing constructors with static factory methods The static factory method here is not a design pattern, mainly refers to static methods of statically modified,

1. Requirements: ArrayList remove duplicate values of strings in the collection (the contents of the string are the same)Requirement: Cannot create a new collection, just do it on the previous collection.2. code example:1 Packagecn.itcast_04;2 3

1. Vector- specific features :(1) Add functionpublic void addelement (Object obj)--add ()(2) Get functionPublic Object elementat (int index)--get ()Public enumeration elements ()--iterator Iterator ()Enumeration (Interface):Boolean hasmoreelements ()

1. Overview and features of Set setCollection|--listSequential (same storage order and fetch order), repeatable|--setUnordered (Inconsistent storage order and fetch order), uniqueHashSet: It does not guarantee the set iteration order, especially it

In real-world development, it is often necessary to open some physical resources in the program, such as database connection, network connection, disk file, etc., after opening these physical resources must be explicitly closed, otherwise it will

Identification of memory leaksIt is necessary to check if there is a memory leak before you deploy the program to the production environment. A preliminary judgment can be made by the garbage collector's indicator.If memory usage continues to rise

Sometimes I think I do nothing, write the program can not do, and then the simple operation will also have problems and so on. Through the "Boulevard to Jane" Reading and the teacher's explanation I know that is a lack of self-confidence, is the

Http://www.jfox.info/40-ge-java-ji-he-lei-mian-shi-ti-he-da-anOrganize from the above link;The Java Collection framework is the foundation of the Java programming language and is an important knowledge point in the Java interview. Here, I've listed

GBK of two bytes. Convert the stream. You can specify a code table when using a transform stream. InputStreamReader in = new InputStreamReader (New FileInputStream ("Abc.txt"), "Utf-8");// Read the text file in utf-8 form outstreamwrtier out = new

Byte stream two base class Inputstreamoutputstream character stream two base class Readerwriter these four abstract classes derive from subclasses whose parent class is the subclass suffix.character Stream:WriterThe action file is primarily a

Zendstudio when connecting to the remote server, the following error is suddenly reportedcaused connection Abort:socket write error 'From last night, have been inquiring to the present. In the link log, the following error is suddenly queried.215

Exception classes in Java are inherited from the Throwable class. An object of the Throwable class can be thrown (throw).Throwable objects can be divided into two groups. One group is unchecked exceptions, and exception handling mechanisms are often

There is no space, connection number, or bottom line link between the words (for example, Camel case, camel-case, or camel_case form). There are two kinds of formats: 1, Small Hump-type nomenclature (lower camel case): The first word starts with a

Java multithreaded programming Summary one – First knowledge multithreadingThe concept of process, multi-process, thread, multithreadingprocess: The execution path of the CPU. The popular word is the program that is running in the system. For

1 What is the difference between collection and collections?Java.util.Collection is a collection interface. It provides a common interface method for basic manipulation of collection objects.The collection interface has many specific implementations

1. Find FilesFind/-name filename.txtfind the Filename.txt file under the name/directory. 2. See if a program is runningPs–ef|grep TomcatSee all processes related to Tomcat3. Terminating a threadkill-9 19979thread that terminates thread number bit 199

Understanding the IO stream of JavaStream concept: A bridge between program and data sourcesClassification of StreamsIn the direction of the stream (from the memory point where the program resides): Input stream: Reads the external input

First, the basic concept1 maxactiveThe maximum number of database connections for the connection pool. Set to 0 means no limit, the maxactive is generally configured as a possible concurrency.2 MaxidleMaximum number of idle connections3