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

【问题标题】：cant access textview or getLayoutInflater() outside oncreate android无法在 oncreate android 之外访问 textview 或 getLayoutInflater()
【发布时间】：2014-04-13 12:42:51
【问题描述】：

我在尝试访问 Enterdata() 中的 textview 时遇到空指针异常； * 该站点正在运行并返回一个 jsonobject * 我在activity_main.xml 中创建了id 通知 * 我可以在 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（顺便说一句，谢谢 4 如此快速的响应）

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;
}

}

日志猫

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

【问题讨论】：

  • 当您在 EnterData 方法中膨胀 R.layout.activity_main 时，您不会访问获取对您的 Activity 的内容视图的引用 - 您只是在创建一个新的（单独的）实例看法。 Hariharan 的回答应该可以为您解决问题。

标签： android oncreate


【解决方案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();
}
}

编辑

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

编辑

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;
}

}
}

【讨论】：

  • 04-13 09:04:59.656: E/AndroidRuntime(2148): at com.example.test.MainActivity.Enterdata(MainActivity.java:41)
  • 第 41 行是：notice.setText(" "+success+" ");
  • @user3528845 第 41 行是什么？
  • 第 41 行是 notice.settext();
  • @user3528845 是否优先考虑成功值？
【解决方案2】：

尝试在Enterdata(JSONObject jsonob) : 39中的代码中进行以下更改

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

【讨论】：

  • 谢谢你的回答，但我使用了两个不同的类，这就是为什么它不起作用得到了解决方案
  • 这并不能解决问题，基本上只是做 OP 正在做的事情。
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