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java lang nullpointerexception,但仅适用于三星GT-N5110 Note 8

adt android java

timv · 技术社区 · 12 年前

我有一个问题,我无法让我的应用程序处理注释8。
与旧的HTC手机一样,Galaxy S4完美无误。

我得到的错误如下

02-21 09:21:28.352: W/dalvikvm(6130): threadid=1: thread exiting with uncaught exception     (group=0x41bab930)
02-21 09:21:28.357: E/AndroidRuntime(6130): FATAL EXCEPTION: main
02-21 09:21:28.357: E/AndroidRuntime(6130): java.lang.RuntimeException: Unable to start     activity ComponentInfo{com.taskey.me2team/com.taskey.me2team.StartHere}:     java.lang.NullPointerException
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2245)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.app.ActivityThread.access$700(ActivityThread.java:150)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.os.Looper.loop(Looper.java:137)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.app.ActivityThread.main(ActivityThread.java:5279)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at java.lang.reflect.Method.invokeNative(Native Method)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at java.lang.reflect.Method.invoke(Method.java:511)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at dalvik.system.NativeStart.main(Native Method)
02-21 09:21:28.357: E/AndroidRuntime(6130): Caused by: java.lang.NullPointerException
02-21 09:21:28.357: E/AndroidRuntime(6130):     at com.taskey.me2team.StartHere.isOnline(StartHere.java:303)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at com.taskey.me2team.StartHere.onCreate(StartHere.java:124)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.app.Activity.performCreate(Activity.java:5276)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
02-21 09:21:28.357: E/AndroidRuntime(6130):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
02-21 09:21:28.357: E/AndroidRuntime(6130):     ... 11 more

代码如下:

启动活动显示启动屏幕,然后进入主活动

package com.mycompany.myappname;

import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.content.Intent;

public class SplashActivity extends Activity {

    // Splash screen timer
    private static int SPLASH_TIME_OUT = 1600;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);
        //getWindow().getDecorView().getBackground().setDither(true);

        new Handler().postDelayed(new Runnable() {

            /*
             * Showing splash screen with a timer. This will be useful when you
             * want to show case your app logo / company
             */

            @Override
            public void run() {

                Intent i = new Intent(SplashActivity.this, StartHere.class);
                startActivity(i);

                finish();
            }
        }, SPLASH_TIME_OUT);
    }

}

现在我的主要活动如下

package com.mycompany.myappname;


import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
//import android.util.Log;
import android.view.Gravity;
import android.view.Menu;
import android.view.MenuItem;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;

@SuppressLint("SetJavaScriptEnabled")

public class StartHere extends Activity {

    final Activity activity = this;
    MenuItem  menu_LogIn, menu_SignUp, go_Back, go_Forward;

    private SharedPreferences userCredentials;
    private Boolean isLoggedIn;
    private String m2tUser;
    private String webURL;


    WebView webView;

    public MyData getUser;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_start_here);

        getUser = ((MyData)getApplicationContext()); 
        userCredentials = getApplicationContext().getSharedPreferences("me2team", MODE_PRIVATE);
        isLoggedIn = userCredentials.getBoolean("LIStatus", false);
        m2tUser = userCredentials.getString("User", "username");

        if (!isLoggedIn)
        {
            Editor m2tEditor = userCredentials.edit();
            m2tEditor.putBoolean("PUStatus", false);
            m2tEditor.putString("Pswd", "5&GEthtFE5");
            m2tEditor.commit();
            MyData setLoggedOff = ((MyData)getApplicationContext());
            setLoggedOff.setCredentialsUser(m2tUser);
            setLoggedOff.setStateOff();
            setLoggedOff.setPremiumUserOff();

            if (m2tUser.contains("username"))
                webURL = getResources().getString(R.string.welcomeURL);         
            else

                webURL = getResources().getString(R.string.splashURL);
        }
        else
        {
            MyData loggingOn = ((MyData)getApplicationContext());
                loggingOn.setCredentialsUser(m2tUser);
                loggingOn.setCredentialsPwd(userCredentials.getString("Pswd", "89798978"));
                loggingOn.setStateOn();
                boolean puStatus = userCredentials.getBoolean("PUStatus", false);
                if (puStatus)
                    loggingOn.setPremiumUserOff();
                else
                    loggingOn.setPremiumUserOn();

        }


        webView = (WebView) findViewById(R.id.webView1);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setSavePassword(false);
        webView.getSettings().setSupportZoom(true);
        webView.getSettings().setBuiltInZoomControls(false); //as per Janet's request
        webView.getSettings().setUseWideViewPort(true);
        webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
        webView.setScrollbarFadingEnabled(false);
        webView.getSettings().setLoadWithOverviewMode(true);
        webView.setInitialScale(70);

        WebSettings settings = webView.getSettings();
        settings.setDomStorageEnabled(true);

        webView.loadUrl(webURL);

        webView.setWebChromeClient(new WebChromeClient() {
            public void onProgressChanged(WebView view, int progress)
            {
                activity.setTitle("Loading...");
                activity.setProgress(progress * 100);             
                if(progress == 100)
                {
                    activity.setTitle(R.string.app_name);

                }

             }
        });

        webView.setWebViewClient(new WebViewClient() {
            @Override
            public void onReceivedError(WebView view, int errorCode, String description, String failingUrl)
            {
                // Handle the error
            }



        });

        if (!isOnline())
        {
            Toast msg = Toast.makeText(StartHere.this,
                      "You dont seem to be connected to the Internet.", Toast.LENGTH_LONG);
             msg.setGravity(Gravity.CENTER, 0, 0);
             msg.show(); 

        }


        webView.loadUrl(webURL);        

    }

    public void goToTeamPage()
    {

        Intent intent = new Intent(this, TeamPage.class);
        startActivity(intent);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);
        getMenuInflater().inflate(R.menu.start_here, menu);
        menu_LogIn = menu.findItem(R.id.currentlyLoggedOut);
        menu_SignUp = menu.findItem(R.id.signUp);
        go_Back = menu.findItem(R.id.goBack);
        go_Forward = menu.findItem(R.id.goForward);
        return true;
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        super.onPrepareOptionsMenu(menu);


            menu_LogIn.setVisible(true);
            go_Back.setVisible(true);
            go_Forward.setVisible(true);
            menu_SignUp.setVisible(true);


        return true;
    }


    @Override
    public boolean onOptionsItemSelected( MenuItem item )
    {
        super.onOptionsItemSelected(item);

        switch (item.getItemId()) 
        {
        case R.id.currentlyLoggedOut:
        {

            Intent intent = new Intent(this, Me2TeamLogIn.class);
            startActivity(intent);
            return true;
        }

        case R.id.signUp:
        {

            Intent intent = new Intent(this, SignUp.class);
            startActivity(intent);
            return true;
        }

        case R.id.goBack:
        {
            if(webView.canGoBack() == true)
            {
                webView.goBack();
            }


            return true;
        }

        case R.id.goForward:
        {

            if(webView.canGoForward() == true)
            {
            webView.goForward();

            }


            return true;
        }

        default:
        return super.onOptionsItemSelected(item);
        }
    }

    @Override
    protected void onStart()
    {
        //Log.wtf("TimV", "OnStart");
        super.onStart();
    }

    @Override
    protected void onResume()
    {

        //Log.wtf("TimV", "OnResume");
        if (isLoggedIn)
        {
            goToTeamPage();
        }
        super.onResume();
    }

    @Override
    protected void onPause()
    {
        //Log.wtf("TimV", "OnPause");
        super.onPause();
    }


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

    if (!isOnline())
    {
        Toast msg = Toast.makeText(StartHere.this,
                  "You dont seem to be connected to the Internet.", Toast.LENGTH_LONG);
         msg.setGravity(Gravity.CENTER, 0, 0);
         msg.show(); 
    }

        MyData loginData = ((MyData)getApplicationContext());       
        isLoggedIn = loginData.getState();      
        if (isLoggedIn)
        {
        //  Log.wtf("TimV", "going to team page");

            Intent intent = new Intent(this, TeamPage.class);
            startActivity(intent);
        }
        else
            {
        //  Log.wtf("TimV", "going to splash page");
            webURL = getResources().getString(R.string.splashURL);
            webView.loadUrl(webURL);

            }               

    }


    public boolean isOnline() {

        ConnectivityManager connMgr = (ConnectivityManager) 
                getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI); 
        boolean isWifiConn = networkInfo.isConnected();
        networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
        boolean isMobileConn = networkInfo.isConnected();

        if (isWifiConn)
            return true;
        else
        {   
            if (isMobileConn)
                return true;
            else
                return false;
        }
    }

}

这个问题真的让我很困惑,因为所有关于这个问题的谷歌搜索都还没有提供答案。

2 回复 | 直到 12 年前

A J 12 年前

我想你的NPE发生在

boolean isMobileConn = networkInfo.isConnected();

? 这是因为Note 8是一款平板电脑。TYPE_MOBILE可以返回null,因为没有移动连接(也不可能有移动连接)。事实上,我本以为其他平板电脑也会出现类似的崩溃。

来自以下文档: http://developer.android.com/reference/android/net/ConnectivityManager.html#getNetworkInfo(int) :

返回所请求网络类型的NetworkInfo对象,如果设备不支持该类型。

只需将networkInfo(第二个)为空视为没有移动连接。

Community Mohan Dere 8 年前

多亏了《La Dee Dah》,我看到了问题。

我当时正在检查平板电脑上的移动连接,所以我同意,它永远不会工作。

以下是错误的方法:

public boolean isOnline() {

        ConnectivityManager connMgr = (ConnectivityManager) 
                getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI); 

        boolean isWifiConn = networkInfo.isConnected();

        networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);

        boolean isMobileConn = networkInfo.isConnected();

        if (isWifiConn)
            return true;
        else
        {   
            if (isMobileConn)
                return true;
            else
                return false;
        }
    }

这是正确的方法,感谢 bvanvelsen's 答复

public boolean isOnline() {


final ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); 

final NetworkInfo networkInfo = cm.getActiveNetworkInfo();

int type = networkInfo.getType();

String typeName = networkInfo.getTypeName();

boolean connected = networkInfo.isConnected();

if (connected)
    return true;
else
    return false;

}