1. What is the primary purpose of a package in Java?
a) To provide a library of executable methods
b) To group related classes and interfaces
c) To enhance the performance of Java applications
d) To compile Java programs
Answer:
b) To group related classes and interfaces
Explanation:
Packages in Java are used to group related classes and interfaces, making the code easier to manage and avoiding name conflicts​“【oaicite:10】“​.
2. What are built-in packages in Java?
a) Packages created by the user
b) Packages from the Java API
c) Default packages used by the Java compiler
d) Packages that come with the Java Development Environment
Answer:
b) Packages from the Java API
Explanation:
Built-in packages, also known as packages from the Java API, are prewritten classes that are included in the Java Development Environment​“【oaicite:9】“​.
3. How do you import a single class from a package in Java?
a) import package.name.*;
b) package import class.name;
c) import package.name.Class;
d) import class.name.package;
Answer:
c) import package.name.Class;
Explanation:
To import a single class from a package, the syntax 'import package.name.Class;' is used​“【oaicite:8】“​.
4. How can you import all the classes from a package in Java?
a) import package.name.*;
b) import all.package.name;
c) package.name.import.*;
d) import *.package.name;
Answer:
a) import package.name.*;
Explanation:
To import all classes from a package, the syntax 'import package.name.*;' is used​“【oaicite:7】“​.
5. What is a user-defined package in Java?
a) A package that comes pre-installed with Java
b) A package defined and created by the Java developer
c) A special type of built-in package
d) An automatically generated package by the Java compiler
Answer:
b) A package defined and created by the Java developer
Explanation:
User-defined packages are those that are created by the Java developer for organizing classes and interfaces​“【oaicite:6】“​.
6. What keyword is used to create a package in Java?
a) package
b) import
c) class
d) public
Answer:
a) package
Explanation:
The 'package' keyword is used to create a package in Java​“【oaicite:5】“​.
7. Where are user-defined packages typically stored in Java?
a) In a separate Java Development Environment
b) In the main method of the Java application
c) In a file system directory, similar to folders on a computer
d) Within the Java API
Answer:
c) In a file system directory, similar to folders on a computer
Explanation:
User-defined packages are stored in a file system directory, much like folders on a computer​“【oaicite:4】“​.
8. Why are packages important in Java?
a) They increase the execution speed of programs
b) They are required for the application to run
c) They help in avoiding name conflicts and organizing code
d) They define the main method of the application
Answer:
c) They help in avoiding name conflicts and organizing code
Explanation:
Packages are important in Java for avoiding name conflicts and for better management and organization of code​“【oaicite:3】“​.
9. What does the 'import' keyword do in Java?
a) It compiles the Java classes
b) It creates a new package
c) It allows the use of classes from different packages
d) It exports Java classes to external environments
Answer:
c) It allows the use of classes from different packages
Explanation:
The 'import' keyword in Java is used to bring certain classes or entire packages into visibility, allowing their usage in the program​“【oaicite:2】“​.
10. What is the result of not using the 'import' statement for a class in another package?
a) The class can still be used without any issues
b) A runtime error occurs
c) The class must be redefined in the current package
d) The class from the other package cannot be used directly
Answer:
d) The class from the other package cannot be used directly
Explanation:
Without using the 'import' statement, classes from other packages cannot be used directly in the program​“【oaicite:1】“​.
11. How do you access a class from a package that is not imported?
a) By redefining the class in the current package
b) By using the fully qualified name of the class
c) By creating an alias for the package
d) It is not possible to access a class from a non-imported package
Answer:
b) By using the fully qualified name of the class
Explanation:
If a package is not imported, a class can still be accessed by using its fully qualified name, which includes the package name​“【oaicite:0】“​.
12. What is the primary benefit of importing specific classes instead of entire packages?
a) It enhances the performance of the program
b) It makes the program easier to read
c) It reduces memory usage
d) It prevents naming conflicts and reduces potential ambiguity
Answer:
d) It prevents naming conflicts and reduces potential ambiguity
Explanation:
Importing specific classes rather than entire packages helps in avoiding naming conflicts and reduces potential ambiguity, as it clearly specifies which classes are being used in the program​“【oaicite:1】“​.