使用初始化塊初始化實例變量。但是，靜態初始化塊只能初始化靜態實例變量。這些塊僅在加載類時執行一次。一個類中可以有多個靜態初始化塊，按照它們在程序中出現的順序被調用。

下面給出了一個演示 Java 中的靜態初始化塊的程序：

例子

public class Demo {
   static int[] numArray = new int[10];
   static {
      System.out.println("Running static initialization block.");
      for (int i = 0; i < numArray.length; i++) {
         numArray[i] = (int) (100.0 * Math.random());
      }
   }
   void printArray() {
      System.out.println("The initialized values are:");
      for (int i = 0; i < numArray.length; i++) {
         System.out.print(numArray[i] + " ");
      }
      System.out.println();
   }
   public static void main(String[] args) {
      Demo obj1 = new Demo();
      System.out.println("For obj1:");
      obj1.printArray();
      Demo obj2 = new Demo();
      System.out.println("\nFor obj2:");
      obj2.printArray();
   }
}

輸出

Running static initialization block.
For obj1:
The initialized values are:
40 75 88 51 44 50 34 79 22 21
For obj2:
The initialized values are:
40 75 88 51 44 50 34 79 22 21