Java.lang package is the fundamental topic in core Java. Here are some topics I have for you to prepare for before appearing in a Java interview.

The package is one of the most fundamental packages in the Java programming language. It contains classes and exceptions that are automatically imported into every Java program. Familiarity with topics related to this package is crucial for any Java developer, and these topics often come up in interviews. Here are some important interview topics from the package:

1. Object Class: Understanding the class, which is the root class for all Java classes, is essential. Interviewers might ask about the methods provided by this class, such as , , and .

2. String Class: The class is widely used in Java. You should be familiar with its methods, immutability, and the difference between string concatenation and using for better performance.

3. Wrapper Classes: Know the wrapper classes for primitive data types like , , and . Be prepared to discuss autoboxing and unboxing.

4. Exception Handling: Understand the exceptions in the package, such as , , and . Be ready to explain checked and unchecked exceptions.

5. System Class: Familiarize yourself with the class and its methods for standard input, output, and error. This is important for I/O operations.

6. Math Class: Know how to use the class for common mathematical operations and functions like , , and .

7. Runtime Class: Be able to discuss the class and its uses in managing the Java Virtual Machine (JVM).

8. Thread Class: Understand the basics of Java threads and how the class is used for creating and managing threads.

9. Class Object Methods: Be prepared to explain the use of methods like , , and for dynamic class loading and reflection.

10. ClassLoader: Discuss the concept of class loading, classpath, and the role of the classloader in Java.

11. Enum Class: Know how to create and use enums, which are often used for defining a fixed set of constants.

12. Intrinsic Locks and Synchronization: Understand the keyword and how intrinsic locks work in Java.

13. Garbage Collection: Be prepared to discuss how Java manages memory through garbage collection and the method.

14. Interning Strings: Explain the concept of string interning using the method.

15. Memory Management: Know about memory allocation and deallocation, the heap, and the stack.

16. Runtime Environment: Discuss how Java runs on different platforms and the role of the class in this context.

17. SecurityManager: Understand the security manager and how it controls the security policies of a Java application.

These topics cover the essentials of the package, and a solid understanding of them will help you in Java interviews. Depending on the job position and the level of expertise required, you may be asked to delve deeper into specific topics.