将 "this" 替换为 "getActivity ()" 后无法访问的语句

Question

我正在尝试使用 viewpager 在 fragment 中创建幻灯片图像。我遇到了一些问题，我无法获得 getActivity() 函数，

之前我用过

adapter = new Home_imageadapter (this, imageResource);

因为我的很多错误将其更改为

adapter = new Home_imageadapter (getActivity (), imageResource);

现在只出现一处错误。

为什么以及如何解决这个问题？

    public class OtherFragment extends Fragment {

    private ViewPager viewPager;
    private Beranda_imageadapter adapter;
    private LinearLayout sliderdotspanel;
    private int dotscount;
    private ImageView[] dots;

    private int[] imageResource = {

            R.drawable.slide3,
            R.drawable.slide1,
            R.drawable.slide2
    };

    public OtherFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View rootView = inflater.inflate(R.layout.fragment_other, container, false);

        viewPager = (ViewPager) rootView.findViewById(R.id.viewpager);
        sliderdotspanel = (LinearLayout) rootView.findViewById(R.id.viewPagerCountDots);
        return rootView;

        adapter = new Beranda_imageadapter(getActivity(), imageResource);

        viewPager.setAdapter(adapter);

        dotscount = adapter.getCount();
        dots = new ImageView[dotscount];for (int i = 0; i < dotscount; i++) {
            dots[i] = new ImageView(getActivity());
            dots[i].setImageDrawable(ContextCompat.getDrawable(getActivity().getApplicationContext(), R.drawable.nonactive_dot));

            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
            params.setMargins(8, 0, 8, 0);

            sliderdotspanel.addView(dots[i], params);
            dots[0].setImageDrawable(ContextCompat.getDrawable(getActivity().getApplicationContext(), R.drawable.active_dots));

        }


        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {

                for (int i = 0; i < dotscount; i++) {
                    dots[i].setImageDrawable(ContextCompat.getDrawable(getActivity().getApplicationContext(), R.drawable.nonactive_dot));
                }
                dots[position].setImageDrawable(ContextCompat.getDrawable(getActivity().getApplicationContext(), R.drawable.active_dots));

            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }
 }

Answer 1

您的代码中间有 return rootView;。将其移至 onCreateView() 方法的最后一行。

Answer 2

必须在设置布局属性后返回视图 [在您的情况下是 rootView]，否则将无法到达之后添加的更改：

像这样更改您的 onCretae 方法：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                     Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_other, container, false);

viewPager = (ViewPager) rootView.findViewById(R.id.viewpager);
sliderdotspanel = (LinearLayout) rootView.findViewById(R.id.viewPagerCountDots);

adapter = new Beranda_imageadapter(getActivity(), imageResource);

viewPager.setAdapter(adapter);

dotscount = adapter.getCount();
dots = new ImageView[dotscount];for (int i = 0; i < dotscount; i++) {
    dots[i] = new ImageView(getActivity());
    dots[i].setImageDrawable(ContextCompat.getDrawable(getActivity().getApplicationContext(), R.drawable.nonactive_dot));

    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
    params.setMargins(8, 0, 8, 0);

    sliderdotspanel.addView(dots[i], params);
    dots[0].setImageDrawable(ContextCompat.getDrawable(getActivity().getApplicationContext(), R.drawable.active_dots));

return rootView;

}

Answer 3

您可以使用 rootView.getContex() 或 rootView.getContex().getActivity() 而不是 getActivity()，您还应该 return 在 onCreateView() 方法末尾使用 rootView。

将 "this" 替换为 "getActivity ()" 后无法访问的语句

unreachable statement after replacing "this" to "getActivity ()"

android

androidimageslider