Java development of the necessary technical points __java

essential Technical points for Java development2016-08-09 Java Technology

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1. Java Run (Prerequisites)

This may look very simple, Java program to run who will not? But very often, we simply execute Java programs through the IDE, and how does the underlying IDE execute Java programs? A lot of people don't understand.

This knowledge point is the most basic Java developers need to master, beginners Java, the first is certainly taught you how to execute Java programs on the command line, but many people once the Java finished, the IDE used, forget this. Why emphasize to know this, know the Java most pure startup way, you can start when the problem, to analyze how many directories started, how to execute naming, parameters, whether there are missing. This will help you to really develop and solve the strange and environment-related problems.

The knowledge that needs to be mastered here is:

Javac compiling Java files as class files

Use of Java commands, how Java classes with package are started on the command line

The various paths that Java programs involve (Classpath, Java. Library Path, Java running home directory, etc.)

　　2. Data type

This is not much to say, nothing more than the basic types of Java and the mastery of object types. You can learn more about how to automate the conversion of the JDK, including the boxed unboxing, and to avoid the same type of judgment after boxing

Main Knowledge Points:

Basic type: int, long, float, double, Boolean, ...

Corresponding object type: Integer and other types to the basic type of conversion, boxing and unboxing

Object type: Equals, hashcode

Character of String type

3. Access Control

This is also a basis for Java encapsulation features, which need to be mastered:

Public protected default private for class, method, field cosmetic effect

4. Process Control

The basics of Java process Control, although some grammars are not necessarily very common, need to be understood and used in the right place.

What you need to know is: If, switch, loop, for, while the process control syntax

5. The concept of object-oriented programming

This is a core concept of Java that requires mastery by any Java developer. Many of the features in Java, or knowledge points, are related to Java object-oriented Programming concepts. In my understanding, a good developer not only needs to understand these features (knowledge points) themselves, but also need to know how these objects in the Java object-oriented Programming concept is reflected, so that more useful for developers to master the Java Development language, as well as other object-oriented programming language. Here is a brief list of the main points of knowledge include:

Object-oriented three main characteristics: encapsulation, inheritance, polymorphism; Individual definition concepts, what are the features embodied, the respective use of the scene

The concept of static multiple dispatch and dynamic single dispatch

The concept and use of overloading

Inheritance: Interface multiple implementations, base class single inheritance

Abstract, abstract class, interface

Polymorphism: The concept of method coverage and its use

Interface callback

6. Objects and instances, creation of objects

In this context, developers need to understand the concepts of class and instance and the differences between them, which is a basis for Java object-oriented features. The main knowledge points are:

The concept of class and Instance;

Instance created process: 1. No inheritance: Allocate memory space, initialize variables, call constructors; 2. Have inheritance: Handle static action, allocate memory space, variable defined as initial value, from base class-> subclass, process definition Place initialization, execute construction method;

Points to note: Static properties, such as initialization from the base class-> subclasses, and default parameterless constructor-related attributes.

7. Static

Static properties are also used frequently in Java daily development to understand the usage associated with the static keyword, as well as with other keywords, such as whether it can be used in conjunction with abstract, final, and other keywords.

The main needs to master are:

Definition of static properties, use, and how classes are initialized when loaded

Definition and use of static methods

Definition and use of static classes

Definition and initialization time of static code block

　　8. Basic Knowledge Points

Here is a list of some of the scattered, no system classification of some Java knowledge points. In the daily development of the use of a lot. This piece of content in fact there are a lot of, currently only temporarily summed up these several here:

Includes: Equals, Hashcode, String/stringbuffer, final, finally, finalize

　　

　　9. Collection Framework

This is a part of the need to learn more, do Java development, you can say that there is no need to assemble the framework, which is very important. But the knowledge here is not difficult, but for the collection it is best to understand the internal implementation, because this helps you to choose the appropriate framework in various scenarios to solve the problem, such as a set of 1W elements, often to do contains judgment operations, know the characteristics of the collection or internal implementation, It's easy to make the right choice.

This includes the following (concurrency related is not included):

System of the Set frame: Basic collection, Map

Specific set implementation of the content, List, set, MAP specific implementation, internal structure, special methods, applicable scenarios

Use of collection-related tool class collections, etc.

　　10. Anomaly Framework

Exceptions may not be as important in Java development as they are. Generally encountered anomalies, directly on the throw, or just catch a bit after processing for the overall operation of the program has no big impact. However, in enterprise-level design and development, the exception of the design and treatment of good or bad, often related to the overall robustness of the system. The exception of a good system for developers, processing should be unified to avoid a lot of exception handling logic scattered everywhere; for the system, the exception should be controllable, and is easy to transport, some anomalies, there should be a way to deal with, know how to Operation dimension processing, so although the exception framework is very simple, But for the enterprise-wide application development, exception handling is very important, dealing with the exception needs to understand the exception system in Java.

This part of the need to master the knowledge point is not much, mainly is:

Abnormal system:

Throwable

Exception

RuntimeException

Error

The difference between runtimeexception and general Exception, specific treatment methods, etc.

　　11.Java IO

IO in Java is not only the file read and write so simple, but also includes the socket network reading and writing, and so on all the input and output operations. For example, the content of post in a standard HTTP request is read as a process of output, etc.

For Io,java not only provides basic input, output-related APIs, but also provides some simplified operation of the reader, writer and other APIs, in some development (involving a large number of IO operations) is also important, in general day-to-day development will involve (log, Temporary file reading and writing, etc.).

The main points of knowledge in this are:

Basic IO Systems: Includes InputStream, OutputStream, reader/writer, file reads, various stream reads, etc.

The concept of NIO, the specific use and use of the scene