//f a method does not handle a checked exception, the method must declare it using the throws keyword. The throws keyword appears at the end of a method's signature. 

One can throw an exception, either a newly instantiated one or an exception that you just caught, by using the throw keyword. 

Understand the difference between throws and throw keywords, throws is used to postpone the handling of a checked exception and throw is used to invoke an exception explicitly. 

Example

import java.io.*;

public class className {

​

   public void deposit(double amount) throws RemoteException {

      // Method implementation

      throw new RemoteException();

   }

   // Remainder of class definition

}

throw new java.lang.Error("this is very bad");

throw new java.lang.RuntimeException("this is not quite as bad");

public static void main(String[] args) {

    Scanner kb = new Scanner(System.in);

    System.out.println("Enter a number");

    try {

        double nb1 = kb.nextDouble();

        if(nb1<0)

            throw new ArithmeticException();

        else System.out.println( "result : " + Math.sqrt(nb1) );

    } catch (ArithmeticException e) {

        System.out.println("You tried an impossible sqrt");

    }

}

public class Main {

  static void checkAge(int age) throws ArithmeticException {

    if (age < 18) {

      throw new ArithmeticException("Access denied - You must be at least 18 years old.");

    }

    else {

      System.out.println("Access granted - You are old enough!");

    }

  }

​

  public static void main(String[] args) {

    checkAge(15); // Set age to 15 (which is below 18...)

  }

}

class Main {

  public static void divideByZero() {

​

    // throw an exception

    throw new ArithmeticException("Trying to divide by 0");

  }

​

  public static void main(String[] args) {

    divideByZero();

  }

}

Throws keyword used for handling exceptions. 

  Where do you use it? Methods signature. 

 If you want to handling right away in selenium or Api use “throws” keyword.

Throw is creating an exception. Basically there are doing opposite. 

Where do you use it? We use it with in the block.

import java.io.*;

class Main {

  public static void findFile() throws IOException {

    // code that may produce IOException

    File newFile=new File("test.txt");

    FileInputStream stream=new FileInputStream(newFile);

  }

​

  public static void main(String[] args) {

    try{

      findFile();

    } catch(IOException e){

      System.out.println(e);

    }

  }

}

import java.io.*;

class Main {

  // declareing the type of exception

  public static void findFile() throws IOException {

    // code that may generate IOException

    File newFile = new File("test.txt");

    FileInputStream stream = new FileInputStream(newFile);

  }

​

  public static void main(String[] args) {

    try {

      findFile();

    }

    catch (IOException e) {

      System.out.println(e);

    }

  }

}

class Main {

  public static void divideByZero() {

    throw new ArithmeticException("Trying to divide by 0");

  }

​

  public static void main(String[] args) {

    divideByZero();

  }

}

accessModifier returnType methodName() throws ExceptionType1, ExceptionType2 … {

  // code

}