Java 网络视图崩溃
我用WebView写了一个网络浏览器,到现在为止一切都很好。我不知道我做了什么,导致应用程序崩溃,每次我打开它。Android Studio没有给我任何代码错误,所以我找不到有什么问题。 这是我的密码: MainActivity.javaJava 网络视图崩溃,java,android,webview,Java,Android,Webview,我用WebView写了一个网络浏览器,到现在为止一切都很好。我不知道我做了什么,导致应用程序崩溃,每次我打开它。Android Studio没有给我任何代码错误,所以我找不到有什么问题。 这是我的密码: MainActivity.java package riveras.kasparsweblser; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.support
package riveras.kasparsweblser;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.KeyEvent;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class MainActivity extends AppCompatActivity {
WebView webview;
private WebView mWebView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
String url = "http://www.google.com";
webview = (WebView) findViewById(R.id.webView);
webview.getSettings().setJavaScriptEnabled(true);
webview.loadUrl(url);
webview.setWebChromeClient(new WebChromeClient());
webview.setWebViewClient(new WebViewClient());
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
mWebView = (WebView) findViewById(R.id.webView);
if (event.getAction() == KeyEvent.ACTION_DOWN) {
switch (keyCode) {
case KeyEvent.KEYCODE_BACK:
if (mWebView.canGoBack()) {
mWebView.goBack();
} else {
finish();
}
return true;
}
}
return super.onKeyDown(keyCode, event);
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:fitsSystemWindows="true"
tools:context=".MainActivity">
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<WebView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/wv"
android:layout_below="@+id/toolbar"
android:layout_alignParentBottom="true" />
<android.support.v7.widget.Toolbar android:id="@+id/toolbar"
android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay"
android:clickable="true"
android:contextClickable="true"
android:elevation="1dp"
android:focusable="false"
android:max="@integer/status_bar_notification_info_maxnum"
android:indeterminate="false"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true"
android:layout_alignParentEnd="true" />
</RelativeLayout>
</android.support.design.widget.CoordinatorLayout>
非常感谢您的帮助,如果您需要更多的代码来查看错误,请告诉我
谢谢
/Rivera您正在调用的
setContentView(R.layout.activity\u main)
,它加载一个布局文件,其中包含一个WebView
和android:id=“@+id/wv
。然后您尝试调用findViewById(R.id.WebView);
。您的小部件id不匹配,它们需要匹配。您正在调用setContentView(R.layout.activity\u main);
,它加载一个布局文件,其中包含一个带有android:id=“@+id/wv
的WebView
。然后尝试调用findviewbyd(R.id.webView)代码>。您的小部件id不匹配,需要匹配。在activity_main.xml中检查您的webview id在activity_main.xml中检查您的webview id
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_main" tools:context=".MainActivity"
android:layout_height="match_parent">
<WebView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/webView"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true" />
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="riveras.kasparsweblser" >
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name"
android:theme="@style/AppTheme.NoActionBar" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
11-23 18:46:56.045 32505-32505/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: riveras.kasparsweblser, PID: 32505
java.lang.RuntimeException: Unable to start activity ComponentInfo{riveras.kasparsweblser/riveras.kasparsweblser.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.webkit.WebSettings android.webkit.WebView.getSettings()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2356)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2418)
at android.app.ActivityThread.access$900(ActivityThread.java:154)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5291)
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:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.webkit.WebSettings android.webkit.WebView.getSettings()' on a null object reference
at riveras.kasparsweblser.MainActivity.onCreate(MainActivity.java:26)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2309)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2418)
at android.app.ActivityThread.access$900(ActivityThread.java:154)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5291)
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:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)