Difference between import and package in Java

1. Introduction

In Java, package and import are two keywords that organize and access Java classes. A package is a namespace that organizes classes and interfaces by functionality and helps to avoid name clashes. The import statement is used to bring certain classes or the entire package into visibility, so you don't have to use the fully qualified name of a class, which includes its package.

2. Key Points

1. package defines a namespace under which classes are stored.

2. import is used to declare classes from other packages to be used in the code.

3. The package statement must be the first line in a Java source file (excluding comments).

4. The import statements must come after the package and before class declarations.

5. Using package, you can create a group of related classes, whereas import allows you to use classes from other packages.

3. Differences

package	import
Used to make Java classes from other packages accessible in the current file without using their fully qualified names.	Used to specify a namespace for the current file, organizing it into a specific package.
Helps to avoid collision by allowing access to classes with the same name from different packages.	Helps in organizing classes into structured directories, enhancing maintainability and avoiding class name conflicts across the application.
Can import a single class, multiple classes, or all classes within a package using the asterisk (*) wildcard.	A file can belong to only one package, and the package statement must be the first line of code in a Java source file (excluding comments).
Optional if the required classes are within the same package or you're using fully qualified class names.	Optional only for default package usage, which is not recommended for anything beyond simple examples or learning exercises.
No direct impact on access level; access still depends on the access modifiers of the classes and members.	Defines the scope at the package level for package-private access, influencing encapsulation and visibility within the application.

4. Example

// File Name: com/example/util/Utility.java
package com.example.util;

public class Utility {
    // utility methods
}

// File Name: com/example/main/MainClass.java
package com.example.main;

import com.example.util.Utility; // Importing a single class

public class MainClass {
    public static void main(String[] args) {
        // Since we imported Utility, we don't need to use com.example.util.Utility
        Utility util = new Utility();
    }
}

// Another way using a wildcard to import all classes in a package
// import com.example.util.*;

Output:

// No output in this case, these are just declarations and imports

Explanation:

1. In Utility.java, the package statement declares that Utility belongs to com.example.util.

2. In MainClass.java, import is used to bring Utility class from com.example.util into visibility.

3. Because of the import statement, you can instantiate Utility using its simple name rather than its fully qualified name.

5. When to use?

- Use the package keyword to organize your classes and control the namespace of your Java applications.

- Use the import keyword to access classes from different packages, making your code cleaner and easier to read.