When Java compiles your code, it doesn’t embed the actual memory addresses of classes, methods, or fields. Instead, it uses symbolic references—basically names and descriptors—that act as placeholders. During the resolution phase of class loading, the JVM translates these symbolic references into direct references (actual pointers or addresses in memory). This means that:
- Symbolic References:
These are the names and type information stored in a class’s constant pool. They describe what class, method, or field is being referred to without knowing its exact memory location. - Direct References:
Once the class is loaded, the JVM locates the actual memory locations of these items and replaces the symbolic references with pointers to these locations. This allows for quick and efficient access during runtime without the overhead of repeated lookups.
In summary, replacing symbolic references with direct ones is a key step that allows Java to convert human-readable names into machine-friendly addresses, thereby speeding up the execution of the program.