Static blocks

Definition

A static block is a block of code enclosed in {} and marked with the static keyword.

• It runs once, automatically, when the class is first loaded into memory, even before any constructor or main method is called.

class AppConfig {
    static String version;
 
    static {
        version = "1.0.0";
        System.out.println("AppConfig 초기화 완료");
    }
}

Why?

• When initializing static variables that need logic (not just direct assignment)
• loading native libraries
  • Some Java programs use .dll or .so files via System.loadLibrary(). Static blocks are perfect for loading them once, during class loading
  • static { System.loadLibrary("nativeLib")}
  • debugging