Java 在内部存储器中本地创建json文件时出错

我想在服务器内部存储json文件。为此，我使用下面的方法。但我犯了个错误。请帮忙

             try { 

                 final String TESTSTRING =jsonBranchArray.toString();


                   FileOutputStream fOut = openFileOutput("samplefile.json",
                                                                        MODE_WORLD_READABLE);
                   OutputStreamWriter osw = new OutputStreamWriter(fOut); 


                   osw.write(TESTSTRING);
                   osw.flush();
                   osw.close();

                    FileInputStream fIn = openFileInput("samplefile.json");
                    InputStreamReader isr = new InputStreamReader(fIn);

                    char[] inputBuffer = new char[TESTSTRING.length()];

                    isr.read(inputBuffer);

                    String readString = new String(inputBuffer);

                    boolean isTheSame = TESTSTRING.equals(readString);

                    Log.i("File Reading stuff", "success = " + isTheSame);


        } catch (IOException ioe) {
                ioe.printStackTrace();
        }

错误是。。08-02 12:26:13.449:W/dalvikvm（23547）：threadid=1:线程以未捕获异常退出（组=0x40015560） 08-02 12:26:13.459:E/AndroidRuntime（23547）：致命异常：主 08-02 12:26:13.459:E/AndroidRuntime（23547）：java.lang.NullPointerException 08-02 12:26:13.459:E/AndroidRuntime（23547）：位于com.example.MainActivity.WriteToFile（MainActivity.java:224） 08-02 12:26:13.459:E/AndroidRuntime（23547）：位于com.example.MainActivity.onClick（MainActivity.java:90） 08-02 12:26:13.459:E/AndroidRuntime（23547）：在android.view.view.performClick（view.java:2485） 08-02 12:26:13.459:E/AndroidRuntime（23547）：在android.view.view$PerformClick.run（view.java:9080） 08-02 12:26:13.459:E/AndroidRuntime（23547）：在android.os.Handler.handleCallback（Handler.java:587） 08-02 12:26:13.459:E/AndroidRuntime（23547）：在android.os.Handler.dispatchMessage（Handler.java:92）上 08-02 12:26:13.459:E/AndroidRuntime（23547）：在android.os.Looper.loop（Looper.java:123） 08-02 12:26:13.459:E/AndroidRuntime（23547）：位于android.app.ActivityThread.main（ActivityThread.java:3683） 08-02 12:26:13.459:E/AndroidRuntime（23547）：位于java.lang.reflect.Method.Invokenactive（本机方法） 08-02 12:26:13.459:E/AndroidRuntime（23547）：位于java.lang.reflect.Method.invoke（Method.java:507） 08-02 12:26:13.459:E/AndroidRuntime（23547）：在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run（ZygoteInit.java:839） 08-02 12:26:13.459:E/AndroidRuntime（23547）：位于com.android.internal.os.ZygoteInit.main（ZygoteInit.java:597） 08-02 12:26:13.459:E/AndroidRuntime（23547）：在dalvik.system.NativeStart.main（本机方法）

示例json是

    {
      "Title" : "........Name....",
  "Logo" : "http://test/1.jpg",
"ID" : "1015",
"Contact":{
   "Title" : " something ",
   "Image" : "http://test/1.jpg",
"ID" : "1016",
   "Full Address" : " something   something   something  something  something ",
   "Contact No" : ".....Post Date with Time....",
   "Mail ID" : ".....Start Date with Time....",
   "SiteLink" : "...wwww.abc.com......",
   "LandLine No" : ".....End Date with Time...."
},
"Activities" : {"News":[
{
   "Image" : "http://test/1.jpg",
"ID" : "1017",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Date" : ".....Post Date...."
},{
   "Image" : "http://test/2.jpg",
"ID" : "1018",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Date" : ".....Post Date...."

},{
   "Image" : "http://test/3.jpg",
"ID" : "1019",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Date" : ".....Post Date...."


},{
   "Image" : "http://test/4.jpg",
"ID" : "1020",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Date" : ".....Post Date...."

},{
   "Image" : "http://test/5.jpg",
"ID" : "1021",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Date" : ".....Post Date...."

},{
   "Image" : "http://test/6.jpg",
"ID" : "1022",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Date" : ".....Post Date...."

},{
   "Image" : "http://test/7.jpg",
"ID" : "1023",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Date" : ".....Post Date...."

}
],
"Events":[
{
   "Image" : "http://test/7.jpg",
"ID" : "1024",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Location" : "......Event Loc......",
   "Start Date" : ".....Start Date with Time....",
   "End Date" : ".....End Date with Time...."
},{
   "Image" : "http://test/3.jpg",
"ID" : "1025",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Location" : "......Event Loc......",
   "Start Date" : ".....Start Date with Time....",
   "End Date" : ".....End Date with Time...."

},{
   "Image" : "http://test/4.jpg",
"ID" : "1026",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Location" : "......Event Loc......",
   "Start Date" : ".....Start Date with Time....",
   "End Date" : ".....End Date with Time...."

},{
   "Image" : "http://test/1.jpg",
"ID" : "1027",
   "Title" : " something ",
   "Description" : " something   something   something  something  something ",
   "Location" : "......Event Loc......",
   "Start Date" : ".....Start Date with Time....",
   "End Date" : ".....End Date with Time...."

}
]...as so on

从错误中我可以看到，您并没有使用异步任务并生成网络请求，请添加一个异步任务并在单独的线程中执行网络请求！

class GetContacts扩展异步任务{
@凌驾
受保护的void onPreExecute（）{
super.onPreExecute（）；
}
@凌驾
受保护的Void doInBackground（Void…参数）{
DefaultHttpClient httpclient=新的DefaultHttpClient（）；
试一试{
HttpGet HttpGet=新HttpGet(
“网址”）；
HttpResponse response=httpclient.execute（httpget）；
字符串jsonResp=EntityUtils.toString（response.getEntity（））；
Log.d（“HTTP”，“Rsponse:+jsonResp”）；
JSONObject JSONObject=新的JSONObject（jsonResp）；
///在此处添加您的代码----------------------------------------->
}捕获（例外e）{
e、 printStackTrace（）；
}
返回null；
}
@凌驾
受保护的void onPostExecute（void结果）{
super.onPostExecute（结果）；
}
}

1）使用

source

标记发布堆栈跟踪，以便于阅读。2） 在代码中突出显示这一行，异常源自

com.example.MainActivity.WriteFile（MainActivity.java:224）

MainActivity.java的第224行是什么？（在com.example.MainActivity.WriteToFile（MainActivity.java:224））我不得不说，这是我见过的最好的过度管理的例子。这么多的文本只说这么少。final String TESTSTRING=jsonBranchArray.toString（）--第224行@user387910。。。。是否正在更新

onPostExecute

中与UI相关的值？否。。我试图从url获取数据并将其保存在内存中。@user387910。。。。在

doInBackground

中尝试

从url

获取数据，并在

onPostExecute

中将其保存在内存中！嗯。。我也这么做了。。但最终字符串TESTSTRING=jsonBranchArray.toString（）中出现错误；--这条线。。

       class GetContacts extends AsyncTask<Void, String, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();


        }

        @Override
        protected Void doInBackground(Void... params) {
            DefaultHttpClient httpclient = new DefaultHttpClient();
            try {
                HttpGet httpget = new HttpGet(
                        "url");
                HttpResponse response = httpclient.execute(httpget);
                String jsonResp = EntityUtils.toString(response.getEntity());
                Log.d("HTTP","Rsponse : "+ jsonResp);

                JSONObject jsonObject = new JSONObject(jsonResp);

                /// ADD YOUR CODE HERE------------------------------------------------------------->


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

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);

        }
    }