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

当我尝试启动该应用程序时，出现 NPE。 我不知道是什么原因造成的。该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输入到编辑文本中并将其提交到网页。 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)

感谢您的帮助。

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

You have

public class MainActivity extends ActionBarActivity

您正在使用支持库中的 ActionBar，并且您的活动需要 Theme.AppCompat

为清单文件中的活动应用 AppCompat 主题。

<activity android:theme="@style/Theme.AppCompat

请检查以下链接中的添加操作栏

http://developer.android.com/guide/topics/ui/actionbar.html 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 http://android-developers.blogspot.in/2013/08/actionbarcompat-and-io-2013-app-source.html

Also btgo未初始化，这会导致NullPointerException