JVM uses several memory areas to store data during program execution. Each memory area has a specific responsibility and plays an important role in managing Java applications efficiently.
Key Points: • Heap Memory stores objects and instance variables. It is shared among all threads and managed by the Garbage Collector. • Stack Memory stores local variables, method calls, and partial results. Each thread has its own stack. • Method Area (Metaspace in Java 8+) stores class metadata, method information, static variables, and runtime constants. • PC (Program Counter) Register stores the address of the currently executing JVM instruction for each thread. • Native Method Stack supports the execution of native methods written in languages such as C or C++.
Example: When a User object is created: • The object is stored in Heap Memory. • The reference variable is stored in Stack Memory. • The User class metadata is stored in Metaspace (Method Area).
Interview Tip: For interviews, remember the JVM memory areas in this order:
1. Heap Memory 2. Stack Memory 3. Method Area (Metaspace) 4. PC Register 5. Native Method Stack
A concise interview answer is:
"JVM memory consists of Heap, Stack, Method Area (Metaspace), PC Register, and Native Method Stack. Heap stores objects, Stack stores method execution data, Method Area stores class metadata, PC Register tracks the current instruction, and Native Method Stack supports native code execution."