相关疑难解决方法(0)

我正在尝试创建我的第一个Android应用程序(一个游戏),但我在开始时遇到了一些困难.

当我运行我的代码时,我收到此错误日志:

05-25 02:41:51.022: WARN/dalvikvm(634): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
05-25 02:41:51.040: ERROR/AndroidRuntime(634): FATAL EXCEPTION: main
05-25 02:41:51.040: ERROR/AndroidRuntime(634): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.stickfigs.nmg/com.stickfigs.nmg.NMG}: java.lang.NullPointerException
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at android.os.Looper.loop(Looper.java:123)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at android.app.ActivityThread.main(ActivityThread.java:4627)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at java.lang.reflect.Method.invokeNative(Native Method)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at java.lang.reflect.Method.invoke(Method.java:521)
05-25 02:41:51.040: ERROR/AndroidRuntime(634):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-25 …

我尝试使用 a 将我的数据从 传递adapter给我的另一个activity，putExtra但是当我单击列表中的一个项目移动到我的第二个时activity，没有检索到任何数据，也没有显示我输入的默认文本。另一种方法呢？或者我想念它什么？这是我的代码：

我的onBindViewHolder：

override fun onBindViewHolder(holder: AlbumsListViewHolder, position: Int) {
    val AlbumsData = albumsData!![position]
    holder.albumsName.text = AlbumsData.title

    Glide.with(holder.itemView)
        .load(AlbumsData.cover)
        .transition(DrawableTransitionOptions.withCrossFade())
        .into(holder.coverImage)

    holder.itemView.setOnClickListener {
        val intent = Intent(holder.itemView.context, TracksActivity::class.java)
        //listener?.onClick(AlbumsData)
        intent.putExtra("dd", "ff")
        holder.itemView.context.startActivity(intent)
    }
}

我的第二个Activity：

class TracksActivity: AppCompatActivity(), TracksView {

    private var albumsAdapter: AlbumsAdapter? = null

    override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
        super.onCreate(savedInstanceState, persistentState)
        setContentView(R.layout.activity_tracks)

        //albumsAdapter = findViewById(R.id.trackslist_recycleview)
        val msg = intent.getStringExtra("dd")
        Log.d("dd", "${msg}")
    } …

我在适配器中创建了一个方法.在这种方法中,我有一个arraylist.我想在一个活动中访问这个arrayList.我怎样才能做到这一点？

适配器:

   public class InviteAdapter extends RecyclerView.Adapter<InviteAdapter.MyViewHolder> {

    private ArrayList<Contact> contactArrayList;
    private Context mContext;

    public class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView name;
        private CheckBox checkBox;

        public MyViewHolder(View view) {
            super(view);
            name = (TextView) view.findViewById(R.id.textContactName);
            checkBox = (CheckBox) view.findViewById(R.id.checkBox);

        }
    }

    public InviteAdapter(Context context, ArrayList<Contact> contactArrayList) {
        this.contactArrayList = contactArrayList;
        this.mContext = context;

    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.invite_contact_item, parent, false);

        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) …