如何在最后一张图片上用按钮关闭viewAdapter

Question

我要做的是单击第三个视图中的按钮关闭图像适配器。

我按照本教程设置视图，效果很好：https://www.journaldev.com/10096/android-viewpager-example-tutorial

现在我要做的是在最后一个视图中使用botton关闭适配器。我收到一个错误，上面写着指向按钮：试图在空对象引用上调用虚拟方法"void android.widget.button.setOnClickListener(android.view.view$OnClickListeners(">

我认为这是因为按钮不在主布局上，而是在视图布局上。那么我如何才能正确访问它来隐藏/关闭适配器

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());
}
}

这是模型对象类

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;
}
}

为了知道它是如何工作的，我想隐藏适配器并显示一个文本视图。我再次认为问题是按钮在另一个布局上，那么我该怎么称呼它呢？

Answer 1

在main类中实现侦听器；将其传递给viewpager。根据需要附加侦听器，仅附加审阅视图。

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());
}
}