Question

我正在开发一个使用JavascriptInterface与我的网站javascript通信的WebView应用程序，我尝试启动MapsActivity并在地图上标记一些点。

我添加到我的项目文件 - ＆gt;新 - ＆gt; Google - ＆gt; Google地图活动

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    context = getApplicationContext();
    ...
    mWebView.addJavascriptInterface(new WebAppInterface(this, activity, regIdFirebase, mWebView, mGoogleApiClient), "WEB2Android");
    ....

WebAppInterface类有许多正常工作的方法，但有一个例外： markPointsOnMap

public class WebAppInterface extends MainActivity {
Context context;
Activity activity;
String regIdFirebase;
WebView mWebView;
Object casaMarcat = null;
GoogleApiClient mGoogleApiClient;

public WebAppInterface(Context c, Activity a, String r, WebView w, GoogleApiClient p) {
    context = c;
    activity = a;
    regIdFirebase = r;
    mWebView = w;
    mGoogleApiClient = p;
}

@JavascriptInterface
public void showToast(String toast) {
    Toast.makeText(context, toast, Toast.LENGTH_SHORT).show();
}
...
@JavascriptInterface
public void markPointsOnMap(String points) {
    Log.d("markPointsOnMap", context.toString());

    Intent i = new Intent(getApplicationContext(), MapsActivity.class);
    i.putExtra("markPoints", points);
    startActivity(i);
}

在Web服务器端，我有一些像这样的简单代码

<p>
    <input type="button" value="Mark Points On Map" onClick="markPointsOnMap('47.179142,27.480926,KokoShannel;47.646331,26.254062,NaturelPiata;47.243562,26.716604,Jatakana;47.211149,27.014350,Placeholder')" />
</p>
<script type="text/javascript">
function markPointsOnMap(points) {
    WEB2Android.markPointsOnMap(points);
}
</script>

我有这个错误：

 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:112)
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at ro.nexuserp.apps.utils.WebAppInterface$override.markPointsOnMap(WebAppInterface.java:116)
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at ro.nexuserp.apps.utils.WebAppInterface$override.access$dispatch(WebAppInterface.java)
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at ro.nexuserp.apps.utils.WebAppInterface.markPointsOnMap(WebAppInterface.java:0)
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at org.chromium.base.SystemMessageHandler.nativeDoRunLoopOnce(Native Method)
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at org.chromium.base.SystemMessageHandler.handleMessage(SystemMessageHandler.java:41)
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at android.os.Looper.loop(Looper.java:158)
 12-14 13:20:01.771 27100-28063/ro.nexuserp.apps W/System.err:     at android.os.HandlerThread.run(HandlerThread.java:61)

我试过这个变种，但结果相同。

Intent i = new Intent(context, MapsActivity.class);

Answer 1

活动必须从上下文对象

开始

@JavascriptInterface
public void markPointsOnMap(String points) {
   Intent i = new Intent(context, MapsActivity.class);
   i.putExtra("markPoints", points);
   >> context.startActivity(i); <<
}

嗯！我失去了几个小时，我得到了-1票：）

从扩展MainActivity

1 个答案: