想开发NFC碰一碰功能，报错：java.lang.NullPointerException: Attempt to invoke virtual method 'void oh

在使用NFC开发碰一碰功能的代码：

NfcController.ReaderModeCallback stub = new NfcController.ReaderModeCallback()

nfcController.setReaderMode(this.getAbility(),stub,1, new PacMapEx());

这里报错报错

java.lang.NullPointerException: Attempt to invoke virtual method 'void ohos.aafwk.ability.HarmonyosApplication.registerAbilityLifecycleCallbacks(ohos.aafwk.ability.AbilityLifecycleCallbacks)' on a null object reference

at ohos.nfc.NfcAbilityManager$NfcAppState.register(NfcAbilityManager.java:73)
at ohos.nfc.NfcAbilityManager.registerHarmonyApplication(NfcAbilityManager.java:111)
at ohos.nfc.NfcAbilityManager$NfcAbilityState.<init>(NfcAbilityManager.java:146)
at ohos.nfc.NfcAbilityManager.getAbilityState(NfcAbilityManager.java:260)
at ohos.nfc.NfcAbilityManager.setReaderMode(NfcAbilityManager.java:218)
at ohos.nfc.NfcController.setReaderMode(NfcController.java:356)