Conditional compilation in Java

Source: Conditional Compilation in Java

All the time, I don't know how to implement #ifdef in Java like C + + ... #endif这样的预编译宏, so the Java code has been used if the judgment, just saw the solution, record.

Use #ifdef ... #endif的代码, if the condition is not met, the compiler will not compile this part of the code. But there is no macro definition in Java.

In fact, there are solutions in Java.

There is one in the Java compiler Optimization mechanism: For statements that are always false in a conditional expression, the compiler generates bytecode for code snippets that are not covered by the condition.

For example:

Final Boolean false ;     if (Debug) {      printf ("I ' m in Debug mode!" );    }  

Note that the above conditional debug must be of the final type. The code in this condition is not compiled into bytecode.

Conditional compilation in Java (GO)