Java class library core framework basic tutorial
Java class library core framework basic tutorial
The Java class library is a set of predefined classes and interfaces for developers in Java programming language.These classes and interfaces are organized in various core frameworks to provide various functions and services.This tutorial will introduce the basic knowledge of the core framework of the Java library and provide some example code to help readers better understand.
1. Overview of the core framework of Java library
The core framework of the Java class library is the basis for the development of Java, which provides many important classes and interfaces to achieve various functions.Some of these core frameworks include:
1. Java collection framework (java.util package): It provides the operation and management of the collection object, including lists (List), collection (set), mapping (MAP), etc.These collection classes provide convenient methods to process and operate data.
2. Java input output framework (java.io package): used to handle input and output operations, including file operation, network operation and streaming operations.The input stream is used to read data, and the output stream is used to write data.
3. Java multi -threaded framework (Java.lang package): It is used to achieve multi -threaded programming, allowing programs to perform multiple tasks at the same time.Multi -threading can improve the efficiency and response of programs, and can better utilize multi -core processors.
4. Java graphics user interface framework (Javax.swing package): It is used to create graphical user interface (GUI), providing various UI components and layout managers.Through these components, developers can easily create user -friendly applications.
2. Basic knowledge of the core framework of Java library
1. Import class library: Before using the class library in the Java program, you need to import the required bag first.You can use Import keywords to import the entire package, or use Import Static keywords to import specific class/interface/static members.
Example code:
import java.util.ArrayList;
import java.io.File;
2. Use class library class: Once the class library is imported, the class and interfaces defined in it can be used.The attributes and methods of the class library can be used by creating objects.
Example code:
ArrayList<String> list = new ArrayList<>();
list.add("Hello");
list.add("World");
System.out.println(list.get(0));
3. Define your own library class: In addition to using the existing class library, developers can also write their own class library classes.You need to use keywords PUBLIC and CLASS to define classes, and then compile attributes and methods in them.
Example code:
public class MyUtils {
public static int add(int a, int b) {
return a + b;
}
}
4. Use the custom class library class: After writing your own class library class, you can use it in other Java programs.It is necessary to compile the class library class into byte code file (.cLASS file), and then use it in other programs by importing packages.
Example code:
import com.myutils.MyUtils;
int result = MyUtils.add(5, 3);
System.out.println(result);
3. Summary
This tutorial briefly introduces the basic knowledge of the core framework of the Java library, covering the Java collection framework, input and output framework, multi -threaded framework, and graphic user interface framework.It also demonstrates how to introduce libraries, uses library classes, and write its own library class.By learning these basic knowledge, readers can better understand and use the core framework of the Java class library to develop powerful applications.
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