ex-exception.md

2.6 Handling Exceptions

Example Code:

The indexOf() method throws a RangeError exception when the specified substring is not found. In this case, the substring name[0] is not found at the index name.length - (name.length+2), so the RangeError exception is thrown.

The try block is used to execute code that might cause an exception. The on clause specifies the type of exception that is expected. In this case, the on clause specifies that a RangeError exception is expected.

The catch clause is used to handle the exception. The catch clause prints the exception message to the console.

The finally block is always executed, regardless of whether an exception is thrown.

In this case, the try block executes the code that calls the indexOf() method. The indexOf() method throws a RangeError exception, which is handled by the on clause. The on clause prints the exception message to the console.

The finally block prints the message "Mission completed!" to the console. This message is always printed, regardless of whether an exception is thrown.

void main(){
  String name = "Dart";

  try{
    print ('Name: $name');
    // The following line generates a RangeError
    name.indexOf(name[0], name.length - (name.length+2));
  } on RangeError catch (exception) {
    print ('On Exception: $exception');
  } 
    catch (exception) {
      print ('Catch Exception: $exception');
  } finally {
    print ('Mission completed!');
  }
}

Example Output:

The result of the print statement is shown below:

Name: Dart
On Exception: substring not found
Mission completed!