What is the difference between using throw and throws in Java, and what are their main functions?

In Java, throw and throws are different constructs related to exception handling:

• throw is an operator used to actually throw (generate) an exception in the code. For example:

throw new IllegalArgumentException("Invalid argument");

• throws is a keyword used in a method declaration to specify that this method may throw certain exceptions, and that the calling code should be prepared to handle or propagate them. For example:

public void readFile() throws IOException {
    // code that may throw IOException
}

In summary:

• throw is for throwing an exception within the method body.
• throws is for declaring potential exceptions in the method signature.