代码没报错就是运行不出来

在Manifest.xml里检查下Default activity

    <application
        android:name=".Robot"
        android:allowBackup="false"
        android:fullBackupOnly="false"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.BallShot">
        <activity
            android:name=".MainActivity"//默认activity
...