How to use the on keyword in Dart

The on keyword

In Dart, the on keyword is used with the try block when we have a certain type of exception to catch.

Syntax

try {
// some code here
}
on exception_type {
// some code here
}

Code

The following code shows how to use the on keyword in Dart:

void main() {
  try {
    // declare variable x and y
    int x = 5, y;
    y = x ~/ 0;
  }
  on IntegerDivisionByZeroException {
    print("Error: Zero division");
  }
}

Explanation

  • Lines 1–12: We create the main() function.
  • Line 2: We wrap the code within a try block to catch any error.
  • Line 4: In main(), we declare two variables of int type, x = 5 and y.
  • Line 5: We assign the result from the computation (x~/0) to y.
  • Line 8: We use on to specify the exception type that occurs.

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