android studio使用requestWindowFeature(Window.FEATURE_PROGRESS);点开程序直接报错崩溃

使用的Android Studio

class：

com.example.myprogressbar;

android.support.v7.app.AppCompatActivity;
android.os.Bundle;
android.view.Window;

MainActivity AppCompatActivity {

    onCreate(Bundle savedInstanceState) {
        .onCreate(savedInstanceState);
        requestWindowFeature(Window.);
        requestWindowFeature(Window.);
        setContentView(R.layout.);
    }
}

logcat：

01-29 20:22:43.004 1190-1190/? E/AndroidRuntime: FATAL EXCEPTION: main

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myprogressbar/com.example.myprogressbar.MainActivity}: android.util.AndroidRuntimeException: requestFeature() must be called before adding content

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)

at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)

at android.app.ActivityThread.access$600(ActivityThread.java:141)

at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)

at android.os.Handler.dispatchMessage(Handler.java:99)

at android.os.Looper.loop(Looper.java:137)

at android.app.ActivityThread.main(ActivityThread.java:5103)

at java.lang.reflect.Method.invokeNative(Native Method)

at java.lang.reflect.Method.invoke(Method.java:525)

at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)

at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)

at dalvik.system.NativeStart.main(Native Method)

Caused by: android.util.AndroidRuntimeException: requestFeature() must be called before adding content

at com.android.internal.policy.impl.PhoneWindow.requestFeature(PhoneWindow.java:226)

at android.app.Activity.requestWindowFeature(Activity.java:3264)

at com.example.myprogressbar.MainActivity.onCreate(MainActivity.java:12)

at android.app.Activity.performCreate(Activity.java:5133)

at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)