有個問題想要問一下:
因我想要用arraylist 把值 直接傳到下一頁，在網路上，我有查到:
https://stackoverflow.com/questions/16462163/java-how-to-access-an-arraylist-of-another-class

但為什麼我把它改成這樣:

public class MainActivity extends AppCompatActivity {

    private int number1 = 50;
    private int number2 = 100;
    private List<Integer> list;

    ARView arView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        list = new ArrayList<Integer>();
        list.add(number1);
        list.add(number2);


        arView = new ARView(this);
        addContentView(arView, new WindowManager.LayoutParams(WindowManager.LayoutParams.FILL_PARENT, WindowManager.LayoutParams.FILL_PARENT));
        getWindow().clearFlags( WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);



    }

    public List<Integer> getList() {

        return list;
    }


    public class ARView extends View{

        MainActivity number;

        public ARView(Context context) {
            super(context);
            number = new MainActivity();
            List<Integer> list = number.getList();
            Log.i("Volley33", String.valueOf(list));
        }


    }
}

我log了list 的value, 它是null呢?
不知道是不是我哪邊的觀念不對，能否請幫忙指正??

我用的語言是android studio 的JAVA

謝謝