For dropdown
In Listing 1 I am using ng-app, ng-controller, ng-model, ng-options, ng-change AngularJS directives.
HTML control div consists Select dropdown which is populated from JSON array countryList using ng-options.
In the scope of Angular controller "drpCountryController" ng-model " selectedCountry " is set with 2 like $scope.selectedCountry = 2;
Sample Code
 
- <script>  
-     var app = angular.module('App', []);  
-     app.controller('drpCountryController',function($scope)  
-     {  
-          $scope.selectedCountry = 2;  
-             $scope.countryList = [{ " Name ": "India", "Id": 1 },   
-         { "Name": "Nepal", "Id": 2 },   
-         { " Name ": "Pakistan", "Id": 3 }]           
-     $scope.drpChange= function()  
-             {$scope.SelectedItemDetails = $scope.selectedCountry; }      
- });  
- </script>  
 
HTML
- <body ng-app="App">  
-     <div ng-controller="drpCountryController">  
-          Employee List<select ng-model="selectedCountry" ng-options="country.Id as   country.Name for country in countryList" ng-change="drpChange()"></select>  
-         <br /><br />  
-         <span>{{SelectedItemDetails}}</span>  
-     </div>  
- </body>  
 
The output looks like Figure 1.
Figure 1 
For Radio button list
In Listing 2 I am using ng-app, ng-controller, ng-model, data-ng-repeat, ng-checked AngularJS directives.
Html control div consists level and radio type input HTML control which is populated from JSON array countryList using data-ng-repeat.
In the scope of Angular controller "rdiobuttonlist" ng-checked is set with 2 like
ng-checked= "{{country.value==2}}".
Listing 2
- <script>  
-     var app = angular.module('App', []);  
-      app.controller('rdiobuttonlist', function ($scope) {  
-             $scope.countryList = [{ " Name ": "India", "Id": 1 },   
-         { "Name": "Nepal", "Id": 2 },   
-         { " Name ": "Pakistan", "Id": 3 }]  
-     });  
- </script>  
 
Html 
- <body ng-app="App">  
- <div ng-controller="rdiobuttonlist" style="background-color:lightgray;padding-left:50px">  
-    <label data-ng-repeat="country in countryList">  
-        <input type="radio" name="radio2" ng-checked="{{country.Id==2}}"  style="margin:0px 5px 0px 10px;"    value="{{country.Id}}"/>{{country.Name}}  
-    </label>  
-  </div></body>  
  
 
 The output looks like Figure 2
Figure 2 
Summary
In this article, I discussed how to set default selected item in the drop-down and how to set the default selected item in radio button list using Angular.