Android web视图不工作

我正在创建一个android webview，但当我执行该程序时，它不会查看网页。我在我的应用程序中创建了一个xml webview，这里是我的主要活动代码。 我的webview是否受java堆限制的影响

//主要活动

private WebView mWebView;

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

    mWebView = (WebView) findViewById(R.id.webview);
    mWebView.getSettings().setJavaScriptEnabled(true);
    mWebView.loadUrl("http://www.google.com");
    mWebView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
    mWebView.setWebViewClient(new HelloWebViewClient());

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }
}

 private class HelloWebViewClient extends WebViewClient {
 @Override
 public boolean shouldOverrideUrlLoading(WebView webview, String url){
 webview.loadUrl(url);
 return true;
 }
 }


@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
        mWebView.goBack();
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

原木猫

05-02 03:31:43.270: D/AndroidRuntime(1722): Shutting down VM
05-02 03:31:43.280: W/dalvikvm(1722): threadid=1: thread exiting with uncaught exception (group=0xb3a19ba8)
05-02 03:31:43.410: E/AndroidRuntime(1722): FATAL EXCEPTION: main
05-02 03:31:43.410: E/AndroidRuntime(1722): Process: com.example.mywebview, PID: 1722
05-02 03:31:43.410: E/AndroidRuntime(1722): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mywebview/com.example.mywebview.MainActivity}: java.lang.NullPointerException
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.os.Handler.dispatchMessage(Handler.java:102)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.os.Looper.loop(Looper.java:136)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.app.ActivityThread.main(ActivityThread.java:5017)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at java.lang.reflect.Method.invokeNative(Native Method)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at java.lang.reflect.Method.invoke(Method.java:515)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at dalvik.system.NativeStart.main(Native Method)
05-02 03:31:43.410: E/AndroidRuntime(1722): Caused by: java.lang.NullPointerException
05-02 03:31:43.410: E/AndroidRuntime(1722):     at com.example.mywebview.MainActivity.onCreate(MainActivity.java:30)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.app.Activity.performCreate(Activity.java:5231)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
05-02 03:31:43.410: E/AndroidRuntime(1722):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
05-02 03:31:43.410: E/AndroidRuntime(1722):     ... 11 more

fragment_main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.shopsystem.anything.FirstActivity"
tools:ignore="MergeRootFrame" >

<WebView
    android:id="@+id/webview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" 
enter code here
/>

这是我的第30张 line.mWebView.getSettings.setJavaScriptEnabledtrue

这表示mWebView为空。WebView位于fragment_main.xml中。所以您需要在片段中初始化WebView

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android.permission.INTERNET权限如何？你的占位符片段的宽度和高度是多少？附加片段后，网络视图是否可见？@Raghunandan:是的。应用程序崩溃了。@AndrewT。是的，我授予了internet权限。@udi看起来webview属于fragment\u first.xml后的片段布局

public static  class PlaceHolderFragment extends Fragment{

WebView mWebView;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

     View rootView = inflater.inflate(R.layout.fragment_main, container, false);
     mWebView = (WebView) rootView.findViewById(R.id.webview);
     mWebView.getSettings().setJavaScriptEnabled(true);
     mWebView.loadUrl("http://www.google.com");
     mWebView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
     mWebView.setWebViewClient(new HelloWebViewClient());
     return rootView;
}