Can we throw an Unchecked Exception from a static block in java?

A static block is a block of code with a static keyword. In general, these are used to initialize the static members. JVM executes static blocks before the main method at the time of class loading.

Example

public class MyClass {
   static{
      System.out.println("Hello this is a static block");
   }
   public static void main(String args[]){
      System.out.println("This is main method");
   }
}

Output

Hello this is a static block
This is main method

Exceptions in static block

Just like any other method in Java when an exception occurs in static block you can handle it using try-catch pair.

Example

import java.io.File;
import java.util.Scanner;
public class ThrowingExceptions{
   static String path = "D://sample.txt";
   static {
      try {
         Scanner sc = new Scanner(new File(path));
         StringBuffer sb = new StringBuffer();
         sb.append(sc.nextLine());
         String data = sb.toString();
         System.out.println(data);
      } catch(Exception ex) {
         System.out.println("");
      }
   }
   public static void main(String args[]) {
   }
}

Output

This is a sample fileThis is main method

Throwing exceptions in static block

Whenever you throw a checked exception you need to handle it in the current method or, you can throw (postpone) it to the calling method.

You cannot use throws keyword with a static block, and more over a static block is invoked at compile time (at the time of class loading) no method invokes it.

Herefore, if you throw an exception using the throw keyword in a static block you must wrap it within try-catch blocks else a compile time error will be generated.

Example

import java.io.FileNotFoundException;
public class ThrowingExceptions{
   static String path = "D://sample.txt";
   static {
      FileNotFoundException ex = new FileNotFoundException();
      throw ex;
   }
   public static void main(String args[]) {
   }
}

Compile time error

ThrowingExceptions.java:4: error: initializer must be able to complete normally
      static {
      ^
ThrowingExceptions.java:6: error: unreported exception FileNotFoundException; must be caught or declared to be thrown
      throw ex;
      ^
2 errors