我的Android应用程序中由Theme.AppCompat引起的IllegalStateException

当我尝试启动应用程序时，我得到了一个N​​PE。 我不知道是什么原因造成的。 应用程序应在网站上显示地图。 然后，用户可以轻松地将他的位置键入edittext并将其提交到网页。 这是我的代码：

package com.timbremer.iimv; import android.content.Context; import android.support.v7.app.ActionBarActivity; import android.support.v7.app.ActionBar; import android.support.v4.app.Fragment; import android.os.Bundle; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.os.Build; import android.view.inputmethod.InputMethodManager; import android.webkit.CookieManager; import android.webkit.WebView; import android.webkit.WebViewClient; import android.widget.Button; import android.widget.EditText; public class MainActivity extends ActionBarActivity { private WebView wv; private EditText etlocation; private Button btclose; private Button btgo; private boolean send; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); send = false; etlocation = (EditText) findViewById(R.id.etlocation); btgo.setOnClickListener(new View.OnClickListener() { private String location; @Override public void onClick(View v) { location = etlocation.getText().toString(); WebView wv = (WebView) findViewById(R.id.wv); wv.getSettings().setBuiltInZoomControls(true); CookieManager.getInstance().setAcceptCookie(true); wv.getSettings().setJavaScriptEnabled(true); wv.getSettings().setLoadWithOverviewMode(true); wv.getSettings().setUseWideViewPort(true); wv.loadUrl("http://www.ingress.com/intel"); wv.setWebViewClient(new WebViewClient() { @Override public boolean shouldOverrideUrlLoading(WebView view, String url) { view.loadUrl(url); return true; } @Override public void onPageFinished(WebView view, String url) { if(!send) { view.loadUrl("javascript:{" + "document.getElementById('adress').value='" + location + "';" + "var form = document.getElementsByName('login');" + "form[0].submit();};" ); send = true; } } }); } }); } } 

这是我的LogCat：

 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.timbremer.iimv/com.timbremer.iimv.MainActivity}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity. at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2215) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2265) at android.app.ActivityThread.access$800(ActivityThread.java:145) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1206) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5081) 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:781) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity. at android.support.v7.app.ActionBarActivityDelegate.onCreate(ActionBarActivityDelegate.java:111) at android.support.v7.app.ActionBarActivityDelegateICS.onCreate(ActionBarActivityDelegateICS.java:58) at android.support.v7.app.ActionBarActivity.onCreate(ActionBarActivity.java:98) at com.timbremer.iimv.MainActivity.onCreate(MainActivity.java:36) 

谢谢你的帮助。

Answer 1

 You need to use a Theme.AppCompat theme (or descendant) with this activity. 

你有

 public class MainActivity extends ActionBarActivity 

您正在使用支持库中的ActionBar，您需要为您的活动安装Theme.AppCompat

为清单文件中的活动应用AppCompat主题。

 http://developer.android.com/guide/topics/ui/actionbar.html 

 另请查看此博客 
  http://android-developers.blogspot.in/2013/08/actionbarcompat-and-io-2013-app-source.html 
 此外， btgo未初始化，这将导致NullPointerException