FlexibleUpdate.java

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_flexible);
        UpdateManager.Builder builder = new UpdateManager.Builder()
                .setActivity(this)
                .setUpdateType(UpdateType.FLEXIBLE);
        final UpdateManager updateManager = builder.create();
        updateManager.setUpdateListener(new UpdateListener() {
            @Override
            public void onUpdateChecked(@NotNull AppUpdateInfo appUpdateInfo, boolean updateAvailable) {
                if (updateAvailable) {
                    updateManager.update(appUpdateInfo);
                }

            }

            @Override
            public void onUpdateCheckFailure(@Nullable Exception exception) {
                if (exception != null) {
                    Log.d("abcd", "error : " + exception.getMessage());
                }
            }

            @Override
            public void onUpdateState(@NotNull InstallState installState, long bytesDownLoaded, long totalBytesToDownLoaded) {
                if (installState.installStatus() == InstallStatus.DOWNLOADED) {
                    updateManager.showSnackBarForCompleteUpdate("업데이트가 완료 되었습니다", ContextCompat.getColor(FlexibleUpdateActivity.this, R.color.colorAccent));
                }
            }
        });
        updateManager.checkUpdate();
    }