throw and throws
Exception: throw and throws
In Java, Exception, throw, and throws are related, but they mean different things.
Exception: An Exception is an abnormal situation/error that occurs while a program is runnign. Example
int a = 10 ; int b = 0; int c = a / b; arithmeticException
Java generates an exception because division by zero is not allows. We can handle it using try-catch.
int age = 15;
if (age < 24){
throw new ArithmeticException("Not eligible to choose person");
}
Here, throw = I am throwing an exception right here.
Syntax: throw new ExceptionType("message");
Example: throw new IOException("File Not found");
throws is used in a method declaration to tell the caller that the method may throw an exception.
void readFile() throws IOException{
//code that may cause IOException
}
Think: throws: This method might throw this exception;
whoever calls me should handle it.
For example:
void readFile() throws IOException{
FileReader f = new FileReader("abx.txt");
}
Then the caller can handle it:
try{
readFile();
}catch(IOException e){
System.out.println("File error!");
}
throw vs throws
| throw | throws |
|---|---|
| Used to actually throw an exception | Used to declare possible exceptions |
| Used inside method/block | Used in method declaration |
| Throws one exception at a time | Can declare multiple exceptions |
| Followed by an exception object | Followed by exception class names |
void test() throws IOException{
if(soemthingWrong){
throw new IOException("Something went wrong!");
}
}
Easy way to memeber
- throw -> THROW the exception
- throws -> TELL that the method THROWS an exception
* Remember that throw and throws are keywords, while Exception is a class hierarchy (Throwable -> Exception ->...) rather than a keyword.