App Crash Join meeting with param

Description
I integrate zoom sdk in my app and all code is given by sdk link how to implement it then after
when i start the app and crash it show null pointer exception i dont know why

java.lang.NullPointerException: Attempt to invoke interface method ‘int us.zoom.sdk.MeetingService.joinMeetingWithParams(android.content.Context, us.zoom.sdk.JoinMeetingParams, us.zoom.sdk.JoinMeetingOptions)’ on a null object reference

here is my code .
after initilize the code

onlineClassBinding.createOnlineClassBtn.setOnClickListener(v → {
String meetingNum = onlineClassBinding.meetingId.getText().toString();
String meetingPassword = onlineClassBinding.meetingPassword.getText().toString();
if (meetingNum.isEmpty() && meetingPassword.isEmpty()) {
ZMToast.show(requireContext(), “Enter Meeting Id And Password”, ZMToast.LENGTH_LONG);
} else
joinMeeting(requireContext(), meetingNum, meetingPassword);
});

private void joinMeeting(Context context, String meetingNumber, String password) {
MeetingService meetingService = ZoomSDK.getInstance().getMeetingService();
JoinMeetingOptions options = new JoinMeetingOptions();
JoinMeetingParams params = new JoinMeetingParams();
params.displayName = “Adnan”; // TODO: Enter your name
params.meetingNo = meetingNumber;
params.password = password;
meetingService.joinMeetingWithParams(context, params, options);
}
Which Mobile Client SDK version?
zoom sdk verison 5.5.1.1317

Hi @adnan.haider3783 Did you call the ZoomSDK.getInstance().initialize() method to initialize the SDK and call meetingService.joinMeetingWithParams method after onZoomSDKInitializeResult callback which indicates successful initialization?