button.setText() 在 onClick() 方法中不起作用

Question

我有一个视图寻呼机，其中每个页面都有一个带有图像、一些文本和一个按钮的卡片视图。单击后，我需要更改每个页面的按钮文本。 所以在 ViewPagerAdapter mapSize.setText() 里面只能在 setOnClickListener() 外面工作，而在 onClick 里面它不起作用。 这是我的 ViewPagerAdapter 类

public class ViewPagerAdapter extends PagerAdapter {

    private List<Model> models;
    private LayoutInflater layoutInflater;
    private Context context;
    private Button mapSize;
    private Integer size;
    private static final String TAG = "ViewPagerAdapter";

    public ViewPagerAdapter(Context context, List<Model> models, String playerName) {
        this.models = models;
        this.layoutInflater = layoutInflater;
        this.context = context;
    }

    @Override
    public int getCount() {
        return models.size();
    }

    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {
        return view.equals(o);
    }

    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, final int position) {
        layoutInflater = LayoutInflater.from(context);
        View view = null;

        ImageView imageView;
        TextView title, desc;
        imageView = view.findViewById(R.id.gameModeImage);
        title = view.findViewById(R.id.title);
        desc = view.findViewById(R.id.description);
        imageView.setImageResource(models.get(position).getImage());
        title.setText(models.get(position).getTitle());
        desc.setText(models.get(position).getDescription());
        mapSize = view.findViewById(R.id.mapSizeBtn);

        mapSize.setText("hello2"); //here works

        mapSize.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mapSize.setText("hello"); //here does not work
            }
        });
        container.addView(view, 0);

        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d(TAG, "This page was clicked: " + position);
                    if (position != 1)
                        Toast.makeText(context, "Coming Soon.", Toast.LENGTH_SHORT).show();
                    else {
                        Intent newGameActivity = new Intent(context, com.game.project.GameActivity.class);
                        newGameActivity.putExtra("size", size);
                        context.startActivity(newGameActivity);
                    }
                }
        });


        return view;
    }

    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        container.removeView((View)object);
    }



}

Answer 1

您为每个项目重新分配您的按钮，一个新项目在您的适配器中实例化。 您必须以这种方式引用您的按钮：

@NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, final int position) {
        layoutInflater = LayoutInflater.from(context);
        View view = null;

        ImageView imageView;
        TextView title, desc;
        imageView = view.findViewById(R.id.gameModeImage);
        title = view.findViewById(R.id.title);
        desc = view.findViewById(R.id.description);
        imageView.setImageResource(models.get(position).getImage());
        title.setText(models.get(position).getTitle());
        desc.setText(models.get(position).getDescription());
        final Button mapSize = view.findViewById(R.id.mapSizeBtn);

        mapSize.setText("hello2"); //here works

        mapSize.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mapSize.setText("hello"); //here does not work
            }
        });
        container.addView(view, 0);

        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d(TAG, "This page was clicked: " + position);
                    if (position != 1)
                        Toast.makeText(context, "Coming Soon.", Toast.LENGTH_SHORT).show();
                    else {
                        Intent newGameActivity = new Intent(context, com.game.project.GameActivity.class);
                        newGameActivity.putExtra("size", size);
                        context.startActivity(newGameActivity);
                    }
                }
        });


        return view;
    }

Answer 2

instantiate item 中的所有项目都应声明为 final 才能正常工作。