错误消息：您需要与此活动一起使用Theme.AppCompat主题

Question

This question has been asked so many times, but still i am unable to solve this problem.

I am trying to show Alert windows in my activity. Its giving me following error message

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

This is my code.

public class CartActivity extends AppCompatActivity 

        btnCheckout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(cbApprove.isChecked()){

                    AlertDialog alertDialog = new AlertDialog.Builder(getApplicationContext()).create();
                    alertDialog.setTitle("Thanks");
                    alertDialog.setMessage("Thanks for participating in ticketing flow. The test ends here for the Beta");
                    alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "Ok", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Intent i = new Intent(getApplicationContext(), MainActivity.class);
                            startActivity(i);
                        }
                    });

                    alertDialog.show();

                }
            }
        });

Manifest File

<activity
    android:name=".ticketing.activities.CartActivity"
    android:label="@string/title_activity_cart"
    android:theme="@style/AppTheme"

    ></activity>

Style v21

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>

I have also changed the style of layout to AppComat.NoActionBar from Layout Design .

Error Message

 FATAL EXCEPTION: main
 Process: com.tixsee.mavs, PID: 15867
 java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
 at android.support.v7.app.AppCompatDelegateImplV7.createSubDecor(AppCompatDelegateImplV7.java:340)
 at android.support.v7.app.AppCompatDelegateImplV7.ensureSubDecor(AppCompatDelegateImplV7.java:309)
 at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:273)
 at android.support.v7.app.AppCompatDialog.setContentView(AppCompatDialog.java:80)
 at android.support.v7.app.AlertController.installContent(AlertController.java:214)
 at android.support.v7.app.AlertDialog.onCreate(AlertDialog.java:256)
 at android.app.Dialog.dispatchOnCreate(Dialog.java:463)
 at android.app.Dialog.show(Dialog.java:288)
 at com.tixsee.mavs.ticketing.activities.CartActivity$1.onClick(CartActivity.java:92)
 at android.view.View.performClick(View.java:5156)
 at android.view.View$PerformClick.run(View.java:20755)
 at android.os.Handler.handleCallback(Handler.java:739)
 at android.os.Handler.dispatchMessage(Handler.java:95)
 at android.os.Looper.loop(Looper.java:145)
 at android.app.ActivityThread.main(ActivityThread.java:5832)
 at java.lang.reflect.Method.invoke(Native Method)
 at java.lang.reflect.Method.invoke(Method.java:372)
 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)

Answer 1

I guess the error is caused because of using AlertDialog in your code. You need to pass your activity's context instead of the application context to the alertdialog builder. Get the context in your AlertDialog Builder using getActivity() instead of using getApplicationContext() . Like this:

AlertDialog alertDialog = new AlertDialog.Builder(getActivity()).create();

Answer 2

Use the following theme in your style

<style name="MyAlertDialogStyle" parent="Theme.AppCompat.Light.Dialog.Alert">
    <!-- Used for the buttons -->
    <item name="colorAccent">#FFC107</item>
    <!-- Used for the title and text -->
    <item name="android:textColorPrimary">#FFFFFF</item>
    <!-- Used for the background -->
    <item name="android:background">#4CAF50</item>
</style>

Answer 3

使用此代码

AlertDialog alertDialog = new AlertDialog.Builder(this).create();