throw and throws in java

In Java, “throw” and “throws” are both related to exception handling, but they serve different purposes.

1. throw: The “throw” keyword is used to explicitly throw an exception within a method or block of code. It is followed by an instance of an exception class or a subclass of the Exception class. When a throw statement is encountered, the normal flow of the program is disrupted, and the exception is thrown. The program then looks for an appropriate exception handler to catch and handle the thrown exception.

Here’s an example of how to use “throw” to throw an exception:

public void divide(int dividend, int divisor) {
    if (divisor == 0) {
        throw new ArithmeticException("Cannot divide by zero");
    }
    int result = dividend / divisor;
    System.out.println("Result: " + result);
}

In the above code, if the divisor is zero, the throw statement will throw an ArithmeticException with a corresponding error message.

2. throws: The “throws” keyword is used in a method signature to declare the exceptions that may be thrown by that method. It indicates that the method might generate an exception and that the caller of the method should be prepared to handle it. Multiple exceptions can be declared using a comma-separated list.

Here’s an example of a method declaration that uses “throws”:

public void readFile(String fileName) throws FileNotFoundException, IOException {
    // Code to read the file
}

In this case, the readFile method is declaring that it might throw a FileNotFoundException or an IOException. Any code calling this method needs to either handle these exceptions using try-catch blocks or declare them to be thrown further up the call stack.

To summarize:

• “throw” is used to throw an exception explicitly within a method or block of code.
• “throws” is used in a method signature to declare the exceptions that might be thrown by that method.

Remember that exceptions are a fundamental part of Java’s error handling mechanism, allowing you to handle and recover from unexpected situations during program execution.