json-parsing errors NullPointerException

Question

Код ниже прост и единственная цель - получить данные json. и я помещаю json в строку и получаю конкретные данные, тогда это дает мне исключение из null-указателя, я искал решение для этого в google, и я действительно не понимаю, что я делаю неправильно ... пожалуйста, помогите меня я новый пчела на андроид развития

это MainActivity Класс

public class MainActivity extends Activity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    TextView tv = (TextView)findViewById(R.id.Text); 

    String strJson="{\n"+ 
      " \"Template\": {\n"+ 
      "  \"id\": \"32229\",\n"+ 
      "  \"Sheet\": {\n"+ 
      "   \"id\": \"T1\",\n"+ 
      "   \"Layout\": {\n"+ 
      "    \"id\": \"L1\",\n"+ 
      "    \"name\": \"AndroidLayout1\",\n"+ 
      "    \"type\": \"RelativeLayout\",\n"+ 
      "    \"width\": \"1022\",\n"+ 
      "    \"height\": \"300\",\n"+ 
      "    \"background-color\": \"none\",\n"+ 
      "    \"border-top\": \"none\",\n"+ 
      "    \"border-right\": \"none\",\n"+ 
      "    \"border-bottom\": \"none\",\n"+ 
      "    \"border-left\": \"none\",\n"+ 
      "    \"Control\": [\n"+ 
      "     {\n"+ 
      "      \"id\": \"C1\",\n"+ 
      "      \"name\": \"TextBox2\",\n"+ 
      "      \"type\": \"TextBox\",\n"+ 
      "      \"left\": \"300\",\n"+ 
      "      \"top\": \"69\",\n"+ 
      "      \"width\": \"200\",\n"+ 
      "      \"height\": \"40\",\n"+ 
      "      \"background-color\": \"rgb(102, 255, 255)\",\n"+ 
      "      \"border-width\": \"2px\",\n"+ 
      "      \"border-color\": \"rgb(204, 0, 0)\"\n"+ 
      "     },\n"+ 
      "     {\n"+ 
      "      \"id\": \"C3\",\n"+ 
      "      \"name\": \"ButtonBox4\",\n"+ 
      "      \"type\": \"ButtonBox\",\n"+ 
      "      \"left\": \"437\",\n"+ 
      "      \"top\": \"199\",\n"+ 
      "      \"width\": \"140\",\n"+ 
      "      \"height\": \"40\",\n"+ 
      "      \"background-color\": \"none\",\n"+ 
      "      \"border-top\": \"none\",\n"+ 
      "      \"border-right\": \"none\",\n"+ 
      "      \"border-bottom\": \"none\",\n"+ 
      "      \"border-left\": \"none\"\n"+ 
      "     },\n"+ 
      "     {\n"+ 
      "      \"id\": \"C5\",\n"+ 
      "      \"name\": \"Calendar6\",\n"+ 
      "      \"type\": \"Calendar\",\n"+ 
      "      \"left\": \"656\",\n"+ 
      "      \"top\": \"169\",\n"+ 
      "      \"width\": \"120\",\n"+ 
      "      \"height\": \"40\"\n"+ 
      "     }\n"+ 
      "    ]\n"+ 
      "   }\n"+ 
      "  }\n"+ 
      " }\n"+ 
      "}"; 

    String data = ""; 
    try { 
     // Create the root JSONObject from the JSON string. 
    JSONObject jsonRootObject = new JSONObject(strJson); 

    //Get the instance of JSONArray that contains JSONObjects 
     JSONArray jsonArray = jsonRootObject.optJSONArray("Layout"); 

     //Iterate the jsonArray and print the info of JSONObjects 
     for(int i=0; i < jsonArray.length(); i++){ 
      JSONObject jsonObject = jsonArray.getJSONObject(i); 

      int id = Integer.parseInt(jsonObject.optString("id").toString()); 
      String name = jsonObject.optString("name").toString(); 
      float type = Float.parseFloat(jsonObject.optString("type").toString()); 

      data += "Node"+i+" : \n id= "+ id +" \n Name= "+ name +" \n Type= "+ type +" \n "; 
     } 

     tv.setText(data); 

    }catch (JSONException e) {e.printStackTrace();} 
} 
} 

это файл манифеста

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="com.example.dynamicparse" 
android:versionCode="1" 
android:versionName="1.0" > 

<uses-sdk 
    android:minSdkVersion="8" 
    android:targetSdkVersion="21" /> 

<application 
    android:allowBackup="true" 
    android:icon="@drawable/ic_launcher" 
    android:label="@string/app_name" 
    android:theme="@style/AppTheme" > 
    <activity 
     android:name="com.example.dynamicparse.MainActivity" 
     android:label="@string/app_name" > 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
</application> 

</manifest> 

это ошибка LogCat

11-15 08:54:11.412: E/AndroidRuntime(1478): FATAL EXCEPTION: main 
11-15 08:54:11.412: E/AndroidRuntime(1478): Process: com.example.dynamicparse, PID: 1478 
11-15 08:54:11.412: E/AndroidRuntime(1478): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.dynamicparse/com.example.dynamicparse.MainActivity}: java.lang.NullPointerException 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.app.ActivityThread.access$800(ActivityThread.java:135) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.os.Handler.dispatchMessage(Handler.java:102) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.os.Looper.loop(Looper.java:136) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.app.ActivityThread.main(ActivityThread.java:5017) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at java.lang.reflect.Method.invokeNative(Native Method) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at java.lang.reflect.Method.invoke(Method.java:515) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at dalvik.system.NativeStart.main(Native Method) 
11-15 08:54:11.412: E/AndroidRuntime(1478): Caused by: java.lang.NullPointerException 
11-15 08:54:11.412: E/AndroidRuntime(1478): at com.example.dynamicparse.MainActivity.onCreate(MainActivity.java:87) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.app.Activity.performCreate(Activity.java:5231) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159) 
11-15 08:54:11.412: E/AndroidRuntime(1478):  ... 11 more 

Answer 1

Делайте это, но он не проверен.

try { 
     JSONObject jsonRootObject=new JSONObject(str); 

     JSONObject templateObj=jsonRootObject.getJSONObject("Template"); 
     JSONObject sheetObj=templateObj.getJSONObject("Sheet"); 
     JSONObject layoutObj=sheetObj.getJSONObject("Layout"); 
     String layoutId=layoutObj.getString("id"); 
     String layoutName=layoutObj.getString("name"); 



     JSONArray controArr=layoutObj.getJSONArray("Control"); 
     for(int i=0;i<controArr.length();i++){ 
      JSONObject controlObj=controArr.getJSONObject(i); 
      String controlId=controlObj.getString("id"); 
      String controlName=controlObj.getString("name"); 




     } 



    } catch (Exception e) { 
     e.printStackTrace(); 
    }