【发布时间】：2016-01-08 06:14:33
【问题描述】：
我为简单的网络浏览器编写了代码，但是当我单击按钮时，应用程序停止显示消息“不幸的是，应用程序已停止”。它向我展示了致命的例外。
我已经发布了 logcat、java 代码以及布局。这三个都在同一个部分。
日志猫
--------- beginning of crash
01-08 11:31:04.144 2603-2603/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.dell.firstapp, PID: 2603
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.webkit.WebView.loadUrl(java.lang.String)' on a null object reference
at com.example.dell.firstapp.MyBrowser.onClick(MyBrowser.java:54)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
01-08 11:31:04.175 1242-1935/? W/ActivityManager﹕ Force finishing activity 1 com.example.dell.firstapp/.MyBrowser
01-08 11:31:04.603 1242-2595/? I/OpenGLRenderer﹕ Initialized EGL, version 1.4
01-08 11:31:04.850 1242-2595/? W/EGL_emulation﹕ eglSurfaceAttrib not implemented
01-08 11:31:04.850 1242-2595/? W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0x9f1d71a0, error=EGL_SUCCESS
01-08 11:31:04.975 1242-1260/? I/Choreographer﹕ Skipped 38 frames! The application may be doing too much work on its main thread.
01-08 11:31:06.604 1242-1260/? W/ActivityManager﹕ Activity pause timeout for ActivityRecord{35c22eec u0 com.example.dell.firstapp/.MyBrowser t18 f}
01-08 11:31:06.614 1242-1260/? I/Choreographer﹕ Skipped 98 frames! The application may be doing too much work on its main thread.
01-08 11:31:14.222 1242-1260/? W/ActivityManager﹕ Launch timeout has expired, giving up wake lock!
public class MyBrowser extends Activity implements View.OnClickListener{
EditText url;
WebView ourBrow;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simplebrowser);
WebView ourBrow=(WebView) findViewById(R.id.wvBrowser);
ourBrow.getSettings().setJavaScriptEnabled(true);
ourBrow.getSettings().setLoadWithOverviewMode(true);
ourBrow.getSettings().setUseWideViewPort(true);
ourBrow.setWebViewClient(new ourViewClient());
try {
ourBrow.loadUrl("http://www.google.com");
}catch (Exception e){
e.printStackTrace();
}
Button go=(Button) findViewById(R.id.bGo);
Button back=(Button) findViewById(R.id.bBack);
Button forward=(Button) findViewById(R.id.bFwd);
Button refresh=(Button) findViewById(R.id.bRefresh);
Button clearHistory=(Button) findViewById(R.id.bHistory);
url=(EditText) findViewById(R.id.etURL);
go.setOnClickListener(this);
back.setOnClickListener(this);
forward.setOnClickListener(this);
refresh.setOnClickListener(this);
clearHistory.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.bGo:
String theWebsite=url.getText().toString();
ourBrow.loadUrl(theWebsite);
//Hiding the keyboard after using an EditText
InputMethodManager imm=(InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(url.getWindowToken(),0);
break;
case R.id.bBack:
if(ourBrow.canGoBack())
ourBrow.goBack();
break;
case R.id.bFwd:
if(ourBrow.canGoForward())
ourBrow.goForward();
break;
case R.id.bRefresh:
ourBrow.reload();
break;
case R.id.bHistory:
ourBrow.clearHistory();
break;
}
}
}
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent" android:layout_height="match_parent">
<LinearLayout
android:weightSum="100"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/etURL"
android:layout_weight="20" />
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Go"
android:id="@+id/bGo"
android:layout_weight="80"
android:layout_marginRight="16dp"/>
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:weightSum="8"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/bBack"
android:text="Go back page"
android:layout_weight="2"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/bFwd"
android:text="Go forward"
android:layout_weight="2"
/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/bRefresh"
android:text="Refresh page"
android:layout_weight="2"/>
<Button android:text="clear History"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/bHistory"
android:layout_weight="2"/>
</LinearLayout>
<WebView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/wvBrowser"></WebView>
</LinearLayout>
【问题讨论】：
-
使用
ourBrow=(WebView) findViewById(R.id.wvBrowser);而不是WebView ourBrow=(WebView) findViewById(R.id.wvBrowser);
标签： android fatal-error crash