apilevel 19 not find class

[SiMaLaoShi]

Could not find class 'android.app.NotificationChannel', referenced from method net.agasper.unitynotification.UnityNotificationManager.CreateChannel
apilevel -26 normal

[SiMaLaoShi]

10-15 15:00:17.237 830-27915/com.teslacoilsw.launcher E/FA: Failed to send current screen to service
10-15 15:00:17.513 27916-27916/net.agasper.notificationtest E/OpenGLRenderer: Getting MAX_TEXTURE_SIZE from GradienCache
10-15 15:00:17.513 27916-27916/net.agasper.notificationtest E/OpenGLRenderer: MAX_TEXTURE_SIZE: 16384
10-15 15:00:17.517 27916-27916/net.agasper.notificationtest E/OpenGLRenderer: Getting MAX_TEXTURE_SIZE from Caches::initConstraints()
10-15 15:00:17.517 27916-27916/net.agasper.notificationtest E/OpenGLRenderer: MAX_TEXTURE_SIZE: 16384
10-15 15:00:17.769 27916-27949/net.agasper.notificationtest E/EGL_adreno: [getAttribValue] Bad attribute idx
10-15 15:00:17.769 27916-27949/net.agasper.notificationtest E/EGL_adreno: tid 27949: eglGetConfigAttrib(636): error 0x3004 (EGL_BAD_ATTRIBUTE)
10-15 15:00:17.769 27916-27949/net.agasper.notificationtest E/EGL_adreno: [getAttribValue] Bad attribute idx
10-15 15:00:17.769 27916-27949/net.agasper.notificationtest E/EGL_adreno: tid 27949: eglGetConfigAttrib(636): error 0x3004 (EGL_BAD_ATTRIBUTE)
10-15 15:00:17.769 27916-27949/net.agasper.notificationtest E/EGL_adreno: [getAttribValue] Bad attribute idx
10-15 15:00:17.769 27916-27949/net.agasper.notificationtest E/EGL_adreno: tid 27949: eglGetConfigAttrib(636): error 0x3004 (EGL_BAD_ATTRIBUTE)
10-15 15:00:18.341 27916-27949/net.agasper.notificationtest E/dalvikvm: Could not find class 'android.app.NotificationChannel', referenced from method net.agasper.unitynotification.UnityNotificationManager.CreateChannel
10-15 15:00:42.941 27916-27949/net.agasper.notificationtest A/libc: Fatal signal 11 (SIGSEGV) at 0x00000000 (code=128), thread 27949 (UnityMain)
10-15 15:00:43.233 473-504/system_process E/InputDispatcher: channel '52c15dd4 net.agasper.notificationtest/com.unity3d.player.UnityPlayerActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
10-15 15:00:43.341 830-27915/com.teslacoilsw.launcher E/FA: Failed to send current screen to service
10-15 15:00:47.437 830-27915/com.teslacoilsw.launcher E/FA: Failed to send current screen to service
10-15 15:00:47.729 28017-28017/net.agasper.notificationtest E/OpenGLRenderer: Getting MAX_TEXTURE_SIZE from GradienCache
10-15 15:00:47.729 28017-28017/net.agasper.notificationtest E/OpenGLRenderer: MAX_TEXTURE_SIZE: 16384
10-15 15:00:47.729 28017-28017/net.agasper.notificationtest E/OpenGLRenderer: Getting MAX_TEXTURE_SIZE from Caches::initConstraints()
10-15 15:00:47.729 28017-28017/net.agasper.notificationtest E/OpenGLRenderer: MAX_TEXTURE_SIZE: 16384
10-15 15:00:47.921 28017-28050/net.agasper.notificationtest E/EGL_adreno: [getAttribValue] Bad attribute idx
10-15 15:00:47.921 28017-28050/net.agasper.notificationtest E/EGL_adreno: tid 28050: eglGetConfigAttrib(636): error 0x3004 (EGL_BAD_ATTRIBUTE)
10-15 15:00:47.921 28017-28050/net.agasper.notificationtest E/EGL_adreno: [getAttribValue] Bad attribute idx
10-15 15:00:47.921 28017-28050/net.agasper.notificationtest E/EGL_adreno: tid 28050: eglGetConfigAttrib(636): error 0x3004 (EGL_BAD_ATTRIBUTE)
10-15 15:00:47.921 28017-28050/net.agasper.notificationtest E/EGL_adreno: [getAttribValue] Bad attribute idx
10-15 15:00:47.921 28017-28050/net.agasper.notificationtest E/EGL_adreno: tid 28050: eglGetConfigAttrib(636): error 0x3004 (EGL_BAD_ATTRIBUTE)
10-15 15:00:48.437 28017-28050/net.agasper.notificationtest E/dalvikvm: Could not find class 'android.app.NotificationChannel', referenced from method net.agasper.unitynotification.UnityNotificationManager.CreateChannel
10-15 15:01:20.877 28017-28050/net.agasper.notificationtest A/libc: Fatal signal 11 (SIGSEGV) at 0x00000000 (code=128), thread 28050 (UnityMain)
10-15 15:01:21.353 830-28100/com.teslacoilsw.launcher E/FA: Failed to send current screen to service

[SiMaLaoShi]

10-15 22:53:01.190 753-753/com.android.systemui E/EGL_emulation: tid 753: eglSurfaceAttrib(1210): error 0x3009 (EGL_BAD_MATCH)
10-15 22:53:20.830 753-753/com.android.systemui E/EGL_emulation: tid 753: eglSurfaceAttrib(1210): error 0x3009 (EGL_BAD_MATCH)
10-15 22:53:21.810 2732-2746/net.agasper.notificationtest A/libc: Fatal signal 11 (SIGSEGV) at 0x00000000 (code=128), thread 2746 (UnityMain)
10-15 22:53:22.174 588-646/system_process E/InputDispatcher: channel '52954de0 net.agasper.notificationtest/net.agasper.notificationtest.UnityPlayerActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
10-15 22:53:22.314 753-753/com.android.systemui E/EGL_emulation: tid 753: eglSurfaceAttrib(1210): error 0x3009 (EGL_BAD_MATCH)
10-15 22:53:22.366 1047-1047/com.android.launcher E/EGL_emulation: tid 1047: eglSurfaceAttrib(1210): error 0x3009 (EGL_BAD_MATCH)

[southrop]

Notification channels were introduced in API level 26 (8.0 Oreo) so it makes sense that the classes don't exist on API level 19.