Dart Programming Examples

Dart Programming - Typedef

dart

typedef ManyOperation(int firstNo , int secondNo); //function signature  
Add(int firstNo,int second){ 
   print("Add result is ${firstNo+second}"); 
} 
Subtract(int firstNo,int second){ 
   print("Subtract result is ${firstNo-second}"); 
}
Divide(int firstNo,int second){ 
   print("Divide result is ${firstNo/second}"); 
}  
Calculator(int a, int b, ManyOperation oper){ 
   print("Inside calculator"); 
   oper(a,b); 
}  
void main(){ 
   ManyOperation oper = Add; 
   oper(10,20); 
   oper = Subtract; 
   oper(30,20); 
   oper = Divide; 
   oper(50,5); 
}

Dart Programming - Adding a Breakpoint

dart

void main() { 
   int a = 10, b = 20, c = 5; 
   c = c * c * c; 
   print("$a + $b = ${a+b}"); 
   print("$a%$b = ${a%b}");  // Add a break point here 
   print("$a*$b = ${a*b}"); 
   print("$a/$b = ${a/b}"); 
   print(c); 
}

Dart Programming - Custom Exceptions

dart

class AmtException implements Exception { 
   String errMsg() => 'Amount should be greater than zero'; 
}  
void main() { 
   try { 
      withdraw_amt(-1); 
   } 
   catch(e) { 
      print(e.errMsg()); 
   }  
finally { 
      print('Ending requested operation.....'); 
   } 
}  
void withdraw_amt(int amt) { 
   if (amt <= 0) { 
      throw new AmtException(); 
   } 
}

Dart Programming - Throwing an Exception

dart

main() { 
   try { 
      test_age(-2); 
   } 
   
   catch(e) { 
      print('Age cannot be negative'); 
   } 
}  
void test_age(int age) { 
   if(age<0) { 
      throw new FormatException(); 
   } 
}

Dart Programming - Finally Block

dart

main() { 
   int x = 12; 
   int y = 0; 
   int res;  
   try { 
      res = x ~/ y; 
   } 
   on IntegerDivisionByZeroException { 
      print('Cannot divide by zero'); 
   } 
   finally { 
      print('Finally block executed'); 
   } 
}

Dart Programming - on…catch

dart

main() { 
   int x = 12; 
   int y = 0; 
   int res;  
   try { 
      res = x ~/ y; 
   }  
   on IntegerDivisionByZeroException catch(e) { 
      print(e); 
   } 
}

Dart Programming - Using the catch Block

dart

main() { 
   int x = 12; 
   int y = 0; 
   int res;  
   try {  
      res = x ~/ y; 
   }  
   catch(e) { 
      print(e); 
   } 
}

Dart Programming - Using the ON Block

dart

main() { 
   int x = 12; 
   int y = 0; 
   int res;  
   try {
      res = x ~/ y; 
   } 
   on IntegerDivisionByZeroException { 
      print('Cannot divide by zero'); 
   } 
}

Dart Programming - Generic Map

dart

void main() { 
   Map <String,String>m={'name':'Tom','Id':'E1001'}; 
   print('Map :${m}'); 
 }

Dart Programming - Generic Queue

dart

import 'dart:collection'; 
void main() { 
   Queue<int> queue = new Queue<int>(); 
   print("Default implementation ${queue.runtimeType}");  
   queue.addLast(10); 
   queue.addLast(20); 
   queue.addLast(30); 
   queue.addLast(40); 
   queue.removeFirst();  
   for(int no in queue){ 
      print(no); 
   } 
}

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