The Java throws keyword is used to declare the exception information that may occur during the program execution. It gives information about the exception to the programmer. It is better to provide the exception handling code so that the normal flow of program execution can be maintained.
Suppose in your java program you using a library method which throws an Exception
So java provides an option, wherein whenever you are using a risky piece of code in the method definition you declare it throws an exception without implementing try catch.
Consider the same example as above with throws in the method declaration.
import java.io.*;
class file1{
public static void main(String[] args) throws IOException{
FileWriter file = new FileWriter("c:\\Data1.txt");
file.write("gtupapers");
file.close();
}
}
Note: To successfully the above codes, first create an empty text file with name Data1.txt in your C drive. In sum, there are two methods to handle Exceptions.
Put the Exception causing code in try and catch block.
Declare the method to be throwing an Exception
If either of the above two is not done, the compiler gives an error. The idea behind enforcing this rule is that you as a programmer are aware that a certain piece of code could be risky and may throw an exception.
What is the difference between throw and throws?
throw
throws
It is used to create a new Exception object and throw it
It is used in method definition, to declare that a risky method is being called.
Using throw keyword you can declare only one Exception at a time
Using throws keyword you can declare multiple exception at a time.
Example:
throw new IOException("can not open connection");
Example:
throws IOException, ArrayIndexBoundException;
Summary
The “Java throw keyword” is used to declare an exception. For any method that will “throw” an exception, it is mandatory that in the calling method, you use throws to list the exception thrown.
