Exception Handling in Dart Programming

18_exception_handling.dart

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+
+// OBJECTIVE: Exception Handling
+// 1. ON Clause
+// 2. Catch Clause with Exception Object
+// 3. Catch Clause with Exception Object and StackTrace Object
+// 4. Finally Clause
+// 5. Create our own Custom Exception
+
+void main() {
+
+	print("CASE 1");
+	// CASE 1: When you know the exception to be thrown, use ON Clause
+	try {
+		int result = 12 ~/ 0;
+		print("The result is $result");
+	} on IntegerDivisionByZeroException {
+		print("Cannot divide by Zero");
+	}
+
+	print(""); print("CASE 2");
+	// CASE 2: When you do not know the exception use CATCH Clause
+	try {
+		int result = 12 ~/ 0;
+		print("The result is $result");
+	} catch (e) {
+		print("The exception thrown is $e");
+	}
+
+	print(""); print("CASE 3");
+	// CASE 3: Using STACK TRACE to know the events occurred before Exception was thrown
+	try {
+		int result = 12 ~/ 0;
+		print("The result is $result");
+	} catch (e, s) {
+		print("The exception thrown is $e");
+		print("STACK TRACE \n $s");
+	}
+
+	print(""); print("CASE 4");
+	// CASE 4: Whether there is an Exception or not, FINALLY Clause is always Executed
+	try {
+		int result = 12 ~/ 3;
+		print("The result is $result");
+	} catch (e) {
+		print("The exception thrown is $e");
+	} finally {
+		print("This is FINALLY Clause and is always executed.");
+	}
+
+	print(""); print("CASE 5");
+	// CASE 5: Custom Exception
+	try {
+		depositMoney(-200);
+	} catch (e) {
+		print(e.errorMessage());
+	} finally {
+		// Code
+	}
+}
+
+class DepositException implements Exception {
+	String errorMessage() {
+		return "You cannot enter amount less than 0";
+	}
+}
+
+void depositMoney(int amount) {
+	if (amount < 0) {
+		throw new DepositException();
+	}
+}