如何使用最后一张图片上的按钮关闭 viewAdapter？

Question

我想做的是单击第三个视图中的按钮关闭图像适配器。

我正在按照本教程设置视图，它工作正常：https://www.journaldev.com/10096/android-viewpager-example-tutorial

现在我要做的是在最后一个视图中用按钮关闭适配器。我收到一个错误，指出指向按钮：尝试在空对象引用

上调用虚拟方法 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)'

我认为这是因为按钮不在主布局上，而是在视图布局上。那么我怎样才能正确地将它访问到 hide/close 适配器

这是主要的

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView3 = findViewById(R.id.textView3);

        textView3.setVisibility(View.INVISIBLE);

        btnClose=findViewById(R.id.btnClose);

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        viewPager.setAdapter(new CustomPagerAdapter(this));
        viewPager.setPageTransformer(true, new ZoomOutPageTransformer());
        btnClose.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                viewPager.setVisibility(View.INVISIBLE);
                textView3.setVisibility(View.VISIBLE);
            }
        });

    }

这是适配器

public class CustomPagerAdapter extends PagerAdapter {

    private Context mContext;

    public CustomPagerAdapter(Context context) {
        mContext = context;
    }

    @Override
    public Object instantiateItem(ViewGroup collection, int position) {
        ModelObject modelObject = ModelObject.values()[position];
        LayoutInflater inflater = LayoutInflater.from(mContext);
        ViewGroup layout = (ViewGroup) inflater.inflate(modelObject.getLayoutResId(), collection, false);
        collection.addView(layout);
        return layout;
    }

    @Override
    public void destroyItem(ViewGroup collection, int position, Object view) {
        collection.removeView((View) view);
    }

    @Override
    public int getCount() {
        return ModelObject.values().length;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == object;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        ModelObject customPagerEnum = ModelObject.values()[position];
        return mContext.getString(customPagerEnum.getTitleResId());
    }

}

这是模型对象class

public enum ModelObject {

    RED(R.string.red, R.layout.view_red),
    BLUE(R.string.blue, R.layout.view_blue),
    GREEN(R.string.green, R.layout.view_green);

    private int mTitleResId;
    private int mLayoutResId;

    ModelObject(int titleResId, int layoutResId) {
        mTitleResId = titleResId;
        mLayoutResId = layoutResId;
    }

    public int getTitleResId() {
        return mTitleResId;
    }

    public int getLayoutResId() {
        return mLayoutResId;
    }

}

为了了解它是如何工作的，我想隐藏适配器并显示文本视图。我再次认为问题是按钮在另一个布局上，所以我该如何调用它？

Answer 1

在 main class 中实现您的侦听器并将其传递给 viewpager。按需附加监听器，仅评论视图。

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    textView3 = findViewById(R.id.textView3);

    textView3.setVisibility(View.INVISIBLE);

    viewPager = (ViewPager) findViewById(R.id.viewpager);
    View.OnClickListener listener = new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {
            viewPager.setVisibility(View.INVISIBLE);
            textView3.setVisibility(View.VISIBLE);
        }
    }
    viewPager.setAdapter(new CustomPagerAdapter(this), listener);
    viewPager.setPageTransformer(true, new ZoomOutPageTransformer());
}


public class CustomPagerAdapter extends PagerAdapter {

    private Context mContext;
    private View.OnClickListener mListener;

    public CustomPagerAdapter(Context context, View.OnClickListener listener) {
        mContext = context;
        mListener = listener;
    }

    @Override
    public Object instantiateItem(ViewGroup collection, int position) {
        ModelObject modelObject = ModelObject.values()[position];
        LayoutInflater inflater = LayoutInflater.from(mContext);
        ViewGroup layout = (ViewGroup) inflater.inflate(modelObject.getLayoutResId(), collection, false);
        collection.addView(layout);

        if (position == 2) {
            View btnClose = layout.findViewById(R.id.btnClose);
            btnClose.setOnClickListener(mListener);
        }
        return layout;
    }

    @Override
    public void destroyItem(ViewGroup collection, int position, Object view) {
        collection.removeView((View) view);
    }

    @Override
    public int getCount() {
        return ModelObject.values().length;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == object;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        ModelObject customPagerEnum = ModelObject.values()[position];
        return mContext.getString(customPagerEnum.getTitleResId());
    }
}

如何使用最后一张图片上的按钮关闭 viewAdapter？

How to close viewAdapter with button on last image?

android

android-viewpager

adapter