通过Android Studio创建webview

Question

我创建Android应用程序的第一天,我被卡住了.我已经按照android studi o 的步骤创建了webview.然而,经过无数个小时,我仍然无法创建webview应用程序.应用程序甚至在加载之前停止在模拟器中显示错误:"不幸的是,应用程序已停止".

任何帮助将不胜感激.我的文件如下:

AndroidManifest.xml中

 <?xml version="1.0" encoding="utf-8"?>        
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="myApp2.com.example.myapplication2.myapp2">
<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="myApp2.com.example.myapplication2.myapp2.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>
<uses-permission android:name="android.permission.INTERNET" />

activity_main.xml中

<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"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="myApp2.com.example.myapplication2.myapp2.MainActivity">

<WebView
    android:id="@+id/activity_main_webview"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

MainActivity.java:

package myApp2.com.example.myapplication2.myapp2;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.webkit.WebSettings;
import android.webkit.WebView;


public class MainActivity extends ActionBarActivity {
    private WebView mWebView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        mWebView = (WebView) findViewById(R.id.activity_main_webview);
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mWebView.loadUrl("http://beta.html5test.com/");
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

}

logcat的:

03-15 13:44:56.652    1995-1995/myApp2.com.example.myapplication2.myapp2 D/dalvikvm? Not late-enabling CheckJNI (already on)
03-15 13:45:01.042    1995-1995/myApp2.com.example.myapplication2.myapp2 W/ActivityThread? Application myApp2.com.example.myapplication2.myapp2 is waiting for the debugger on port 8100...
03-15 13:45:01.112    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? Sending WAIT chunk
03-15 13:45:01.162    1995-2001/myApp2.com.example.myapplication2.myapp2 I/dalvikvm? Debugger is active
03-15 13:45:01.322    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? Debugger has connected
03-15 13:45:01.332    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:01.572    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:01.772    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:01.982    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:02.202    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:02.522    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:02.762    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:02.992    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:03.212    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:03.402    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:03.622    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:03.832    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:04.062    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:04.292    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:04.532    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:04.742    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:04.992    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:05.192    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? waiting for debugger to settle...
03-15 13:45:05.532    1995-1995/myApp2.com.example.myapplication2.myapp2 I/System.out? debugger has settled (1509)
03-15 13:45:12.782    1995-1995/myApp2.com.example.myapplication2.myapp2 D/AndroidRuntime? Shutting down VM
03-15 13:45:12.862    1995-1995/myApp2.com.example.myapplication2.myapp2 W/dalvikvm? threadid=1: thread exiting with uncaught exception (group=0xb3aa7ba8)
03-15 13:45:14.102    1995-1995/myApp2.com.example.myapplication2.myapp2 E/AndroidRuntime? FATAL EXCEPTION: main
    Process: myApp2.com.example.myapplication2.myapp2, PID: 1995
    java.lang.RuntimeException: Unable to start activity ComponentInfo{myApp2.com.example.myapplication2.myapp2/myApp2.com.example.myapplication2.myapp2.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at myApp2.com.example.myapplication2.myapp2.MainActivity.onCreate(MainActivity.java:15)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

嘿,我已经设法让它工作.只需重新安排您的代码,如下onCreate(): -

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

    mWebView = (WebView) findViewById(R.id.activity_main_webview);
    WebSettings webSettings = mWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    mWebView.loadUrl("http://beta.html5test.com/");
}

Android清单文件: - 之前写下您的许可 <application>

<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
    android:name="myApp2.com.example.myapplication2.myapp2.MainActivity"
    android:label="@string/app_name" >
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>