Question

我在尝试访问Enterdata（）中的textview时遇到空指针异常; *该网站正在运行并返回一个jsonobject *我在activity_main.xml中创建了id通知 *我能够在oncreate方法中编辑和访问它请帮忙

package com.example.test;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity {

    int success = 56;
   // String requestUrl = "http://hitesh.comeze.com/minor/index.phphttp://hitesh.comeze.com/minor/index.php";
    @SuppressLint("NewApi") @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy); 
        setContentView(R.layout.activity_main);

        new jsop().execute("");
    }

public void Enterdata(JSONObject jsonob) {
    try {
        View myTestView = getLayoutInflater().inflate(R.layout.activity_main, null);
        TextView  notice = (TextView) myTestView.findViewById(R.id.notice);
        success = jsonob.getInt("success");
        Log.d("hi", " "+success);
        System.out.print(success);
        notice.append(" "+success+" ");
    } catch (JSONException e) {
        e.printStackTrace();
    }
}
}
class jsop extends AsyncTask<String,String,JSONObject>
{
    static InputStream is = null;
    static JSONObject jObj = null;
    static String json="";
    @Override
    protected JSONObject doInBackground(String... params) {
        return getJSONFromUrl("http://hitesh.comeze.com/minor/index.php");
    }
    protected void onPostExecute(JSONObject jsonob) {
    new MainActivity().Enterdata(jsonob);
    }
    public JSONObject getJSONFromUrl(String url) {

        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            if(httpResponse!=null)
            {HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();
            }
            else
            {
                System.out.print("htttpresponse");
            }
        } 
        catch (Exception e) {
        e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
        String line = null;
        if(reader!=null)
        {
        while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
        }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

   // try parse the string to a JSON object
    try {
        jObj = new JSONObject(json);
 } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }

    // return JSON String
        return jObj;
}

}

这是日志文件

04-13 08:33:03.046: D/gralloc_goldfish(1917): Emulator without GPU emulation detected.
04-13 08:33:04.506: D/AndroidRuntime(1917): Shutting down VM
04-13 08:33:04.506: W/dalvikvm(1917): threadid=1: thread exiting with uncaught exception (group=0xb2a75ba8)
04-13 08:33:04.536: E/AndroidRuntime(1917): FATAL EXCEPTION: main
04-13 08:33:04.536: E/AndroidRuntime(1917): Process: com.example.test, PID: 1917
04-13 08:33:04.536: E/AndroidRuntime(1917): java.lang.NullPointerException
04-13 08:33:04.536: E/AndroidRuntime(1917):     at android.app.Activity.getLayoutInflater(Activity.java:3338)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at com.example.test.MainActivity.Enterdata(MainActivity.java:39)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at com.example.test.jsop.onPostExecute(MainActivity.java:60)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at com.example.test.jsop.onPostExecute(MainActivity.java:1)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at android.os.AsyncTask.finish(AsyncTask.java:632)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at android.os.AsyncTask.access$600(AsyncTask.java:177)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at android.os.Looper.loop(Looper.java:136)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at java.lang.reflect.Method.invokeNative(Native Method)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at java.lang.reflect.Method.invoke(Method.java:515)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-13 08:33:04.536: E/AndroidRuntime(1917):     at dalvik.system.NativeStart.main(Native Method)
04-13 08:38:04.626: I/Process(1917): Sending signal. PID: 1917 SIG: 9

应用hariharan的建议后的代码和日志（顺便说一下，这样快速的反应）

package com.example.test;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity {

    int success = 56;
    TextView notice;
   // String requestUrl = "http://hitesh.comeze.com/minor/index.phphttp://hitesh.comeze.com/minor/index.php";
    @SuppressLint("NewApi") @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy); 
        setContentView(R.layout.activity_main);
        notice = (TextView) findViewById(R.id.notice);
        new jsop().execute("");
    }

public void Enterdata(JSONObject jsonob) {
    try {
        success = jsonob.getInt("success");
        notice.setText(" "+success+" ");
    } catch (JSONException e) {
        e.printStackTrace();
    }
}
}
class jsop extends AsyncTask<String,String,JSONObject>
{
    static InputStream is = null;
    static JSONObject jObj = null;
    static String json="";
    @Override
    protected JSONObject doInBackground(String... params) {
        return getJSONFromUrl("http://hitesh.comeze.com/minor/index.php");
    }
    protected void onPostExecute(JSONObject jsonob) {
    new MainActivity().Enterdata(jsonob);
    }
    public JSONObject getJSONFromUrl(String url) {

        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            if(httpResponse!=null)
            {HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();
            }
            else
            {
                System.out.print("htttpresponse");
            }
        } 
        catch (Exception e) {
        e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
        String line = null;
        if(reader!=null)
        {
        while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
        }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

   // try parse the string to a JSON object
    try {
        jObj = new JSONObject(json);
 } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }

    // return JSON String
        return jObj;
}

}

logcat的

04-13 09:04:58.086: D/gralloc_goldfish(2148): Emulator without GPU emulation detected.
04-13 09:04:59.626: D/AndroidRuntime(2148): Shutting down VM
04-13 09:04:59.626: W/dalvikvm(2148): threadid=1: thread exiting with uncaught exception (group=0xb2a75ba8)
04-13 09:04:59.656: E/AndroidRuntime(2148): FATAL EXCEPTION: main
04-13 09:04:59.656: E/AndroidRuntime(2148): Process: com.example.test, PID: 2148
04-13 09:04:59.656: E/AndroidRuntime(2148): java.lang.NullPointerException
04-13 09:04:59.656: E/AndroidRuntime(2148):     at com.example.test.MainActivity.Enterdata(MainActivity.java:41)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at com.example.test.jsop.onPostExecute(MainActivity.java:57)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at com.example.test.jsop.onPostExecute(MainActivity.java:1)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at android.os.AsyncTask.finish(AsyncTask.java:632)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at android.os.AsyncTask.access$600(AsyncTask.java:177)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at android.os.Looper.loop(Looper.java:136)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at java.lang.reflect.Method.invokeNative(Native Method)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at java.lang.reflect.Method.invoke(Method.java:515)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-13 09:04:59.656: E/AndroidRuntime(2148):     at dalvik.system.NativeStart.main(Native Method)
04-13 09:09:59.796: I/Process(2148): Sending signal. PID: 2148 SIG: 9

Answer 1

试试这个..

使用notice.setText(" "+success+" ");

TextView  notice;
@SuppressLint("NewApi") @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy); 
    setContentView(R.layout.activity_main);
    notice = (TextView) findViewById(R.id.notice);
    new jsop().execute("");
}

public void Enterdata(JSONObject jsonob) {
try {        
    success = jsonob.getInt("success");
    Log.d("hi", " "+success);
    System.out.print(success);
    notice.setText(" "+success+" ");
} catch (JSONException e) {
    e.printStackTrace();
}
}

修改

protected void onPostExecute(JSONObject jsonob) { Enterdata(jsonob); }

修改

package com.example.test; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONException; import org.json.JSONObject; import android.annotation.SuppressLint; import android.app.Activity; import android.os.AsyncTask; import android.os.Bundle; import android.os.StrictMode; import android.util.Log; import android.view.View; import android.widget.TextView; public class MainActivity extends Activity { int success = 56; TextView notice; // String requestUrl = "http://hitesh.comeze.com/minor/index.phphttp://hitesh.comeze.com/minor/index.php"; @SuppressLint("NewApi") @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); StrictMode.setThreadPolicy(policy); setContentView(R.layout.activity_main); notice = (TextView) findViewById(R.id.notice); new jsop().execute(""); } public void Enterdata(JSONObject jsonob) { try { success = jsonob.getInt("success"); notice.setText(" "+success+" "); } catch (JSONException e) { e.printStackTrace(); } } class jsop extends AsyncTask<String,String,JSONObject> { static InputStream is = null; static JSONObject jObj = null; static String json=""; @Override protected JSONObject doInBackground(String... params) { return getJSONFromUrl("http://hitesh.comeze.com/minor/index.php"); } protected void onPostExecute(JSONObject jsonob) { new MainActivity().Enterdata(jsonob); } public JSONObject getJSONFromUrl(String url) { // Making HTTP request try { // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); HttpResponse httpResponse = httpClient.execute(httpPost); if(httpResponse!=null) {HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } else { System.out.print("htttpresponse"); } } catch (Exception e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; if(reader!=null) { while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } }

Answer 2

尝试在Enterdata(JSONObject jsonob) : 39

中对代码进行以下更改

 myTextView = ((LayoutInflater) MainActivity.this.getSystemService("layout_inflater"))
             .inflate(R.layout.activity_main, null);

无法在oncreate android之外访问textview或getLayoutInflater（）

2 个答案: