native keyword is used for java methods.
A method with native keyword indicates that it is implemented in platform-dependent code, typically written in another programming language such as C, C++.
The Java Native Interface (JNI) enables Java code running in a Java Virtual Machine (JVM) to call, and to be called by, native applications (programs specific to a hardware and operating system platform) and libraries written in other languages such as C, C++ and assembly.
The body of a native method is given as a semicolon only, indicating that the implementation is omitted, instead of a block.
Some the native methods in Runtime Class
- public native int availableProcessors();
- public native long freeMemory();
- public native long totalMemory();
- public native long maxMemory();
- public native void gc();
Some of the native methods in System Class that we use on regular basis.
- public static native long currentTimeMillis();
- public static native long nanoTime();