如何用 Java 创建包？
Java 中的 Package 是封装一组类、子包和接口的机制。我们所需要做的就是将相关的类放入包中。之后，我们可以简单地从现有的包中编写一个导入类，并在我们的程序中使用它。包是一组相关类的容器，其中一些类是可访问的，被公开，而另一些被保留用于内部目的。我们可以在程序中根据需要多次重用包中的现有类。包名和目录结构密切相关
方式:java 中有两种类型的包:
- User-defined package (create your own package)
- Built-in packages are packages from Java application programming interface and Java API, such as swing, util, net, io, AWT, lang, javax , etc.
在本文中，我们将看到如何用 Java 创建一个包？。包是一组相似类型的类、接口和子包。我们使用包是为了避免名称冲突。
语法:导入包
import package.name.*;
示例:导入包
T5】Java
// Java Program to Import a package
// Importing java utility package
import java.util.*;
// Main Class
class GFG {
// Main driver method
public static void main(String[] args)
{
// Scanner to take input from the user object
Scanner myObj = new Scanner(System.in);
String userName;
// Display message
// Enter Your Name And Press Enter
System.out.println("Enter You Name");
// Reading the integer age entered using
// nextInt() method
userName = myObj.nextLine();
// Print and display
System.out.println("Your Name IS : " + userName);
}
}
输出
Enter You Name
Your Name IS : 0
在上面的程序中，导入了‘Java . util’包，并为一个简单的程序运行。这些被称为内置包。
现在，为了用 java 创建一个包，请按照下面描述的特定步骤操作:
- First, we should choose a name for the package to be created and included. The command is in the first line of java program source code.
- You can further include classes, interfaces, annotation types, etc. required in the package. For example, the following single statement creates a package name named " first package" .
语法:声明要创建的包的名称。package 语句只是定义定义的类属于哪个包。
package FirstPackage ;
实现:要在包内创建类
- First, declare the package name as the first statement of our program.
- Then we can use a class as part of the package.
例 1:
爪哇
// Name of package to be created
package FirstPackage;
// Class in which the above created package belong to
class Welcome {
// main driver method
public static void main(String[] args)
{
// Print statement for the successful
// compilation and execution of the program
System.out.println(
"This Is The First Program Geeks For Geeks..");
}
}
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