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我是开发android应用程序的新手。我一直在阅读这里和其他网站的提要来学习。当我单击一个名为 Social 的按钮时，我得到了不幸 [appname] 已停止。我正在构建一个应用程序，这就是我所拥有的：

MainActivity.java

Button btnOut = (Button)findViewById(R.id.btnOut);
btnOut.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {      
    final Dialog alertbox = new Dialog(MainActivity.this);
        alertbox.setContentView(R.layout.button);
    alertbox.setTitle("News - Choose One:");
                Button world = (Button) alertbox.findViewById(R.id.world);
                world.setOnClickListener(new View.OnClickListener() {
                @Override
                    public void onClick(View v) {
                        WebView myWebView = (WebView) findViewById(R.id.webview2);
                        myWebView.setWebViewClient(new WebViewClient());
                        setContentView(myWebView);
                        myWebView.loadUrl("http://news.yahoo.com/world");
                    }
                });  
                Button tech = (Button) alertbox.findViewById(R.id.tech);
                tech.setOnClickListener(new View.OnClickListener() {
                @Override
                    public void onClick(View v) {
                        WebView myWebView = (WebView) findViewById(R.id.webview2);
                        myWebView.setWebViewClient(new WebViewClient());
                        setContentView(myWebView);
                        myWebView.loadUrl("http://news.yahoo.com/tech");
                    }
                });  
                Button sport = (Button) alertbox.findViewById(R.id.sport);
                sport.setOnClickListener(new View.OnClickListener() {
                @Override
                    public void onClick(View v) {
                        WebView myWebView = (WebView) findViewById(R.id.webview2);
                        myWebView.setWebViewClient(new WebViewClient());
                        setContentView(myWebView);
                        myWebView.loadUrl("http://sports.yahoo.com");
                    }
                });
                alertbox.show();
            }
        });

WebActivity2.java

<?xml version="1.0" encoding="utf-8"?>

<WebView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:id="@+id/webview2" >

</WebView>

显现：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.nicx.amazing"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="17" />
    <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=".SplashActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
            </intent-filter>
        </activity>

</manifest>

编辑＃2（对不起，我之前放错了logcat）：LOGCAT 

04-09 20:04:40.348: W/dalvikvm(26501): threadid=1: thread exiting with uncaught exception (group=0x40abc210)
04-09 20:04:40.378: E/AndroidRuntime(26501): FATAL EXCEPTION: main
04-09 20:04:40.378: E/AndroidRuntime(26501): java.lang.NullPointerException
04-09 20:04:40.378: E/AndroidRuntime(26501):    at com.nicx.amazing.MainActivity$3$1.onClick(MainActivity.java:127)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at android.view.View.performClick(View.java:3574)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at android.view.View$PerformClick.run(View.java:14293)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at android.os.Handler.handleCallback(Handler.java:605)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at android.os.Handler.dispatchMessage(Handler.java:92)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at android.os.Looper.loop(Looper.java:137)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at android.app.ActivityThread.main(ActivityThread.java:4448)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at java.lang.reflect.Method.invokeNative(Native Method)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at java.lang.reflect.Method.invoke(Method.java:511)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
04-09 20:04:40.378: E/AndroidRuntime(26501):    at dalvik.system.NativeStart.main(Native Method)

任何帮助将不胜感激。谢谢！

4

1 回答 1

0

这是你的罪魁祸首：

04-09 20:04:40.378: E/AndroidRuntime(26501): java.lang.NullPointerException
04-09 20:04:40.378: E/AndroidRuntime(26501):    at com.nicx.amazing.MainActivity$3$1.onClick(MainActivity.java:127)

在 MainActivity.java 的第 127 行中，您得到了null参数值。

于 2013-04-09T12:15:44.693 回答