无法识别启动活动

Question

have had this problem for a while I just installed android studio and I have been having this problem:

Could not identify launch activity: Default Activity not found Error while Launching activity

... I have this problem with existing projects MyApp I tried to make new project but the same error still

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.android.app.myapplication">

        <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/ic_launcher_round"
            android:supportsRtl="true"
            android:theme="@style/AppTheme">
            <activity android:name=".MainActivity">
                <intent-filter>
                    <action android:name="android.intent.action.MAIN"/>
                    <category android:name="android.intent.category.LAUNCHER"/>
                </intent-filter>
            </activity>
        </application>

    </manifest>

Answer 1

文件->使缓存无效/重新启动...