Hi everyone in this blog I’m explaining about throw keyword in java. 

Details: 

The java throw keyword is used to explicitly throw an exception. We can throw either checked or unchecked exception in java by throw keyword. The throw keyword is mainly used to throw the custom exception.

How to throw the exception:

Before you can catch an exception, some code somewhere must throw one. Any code can throw an exception: your code, code from a package written by someone else such as the packages that come with the Java platform, or the Java runtime environment. Regardless of what throws the exception, it's always thrown with the throw statement.

As you have probably noticed, the Java platform provides numerous exception classes. All the classes are descendants of the Throwable class, and all allow programs to differentiate among the various types of exceptions that can occur during the execution of a program.

You can also create your own exception classes to represent problems that can occur within the classes you write. In fact, if you are a package developer, you might have to create your own set of exception classes to allow users to differentiate an error that can occur in your package from errors that occur in the Java platform or other packages.

java throw keyword example:

in this example, we have created the validate method that takes integer value as a parameter. If the age is less than 18, we are throwing the ArithmeticException otherwise print a message welcome to vote.

public class TestThrow1

{ 

   static void validate(int age)

   { 

     if(age<18) 

      throw new ArithmeticException("not valid"); 

     else 

      System.out.println("welcome to vote"); 

   } 



   public static void main(String args[])

   { 

     validate(13); 

     System.out.println("rest of the code..."); 

   } 

} 

Output:

Exception in thread main java.lang.ArithmeticException: not valid

check more post on exception handling here