将点击侦听器添加到 PagerAdpater CardViews 中的两个按钮

Question

在我的项目中，我有一个 PagerAdapter 来扩充 CardView，这些 CardView 包含用户创建的文本对象。

在每个 CardView 上，我都有编辑和删除按钮来访问与包含文本对象的 ArrayList 相关的方法。

我在我的适配器中编写了一个接口来处理在文本对象创建过程中进行的点击 activity。但是，我的适配器中的 instatiateItem 方法现在显示在 @Override 注释上“方法不覆盖其超类中的方法”。当我删除 @Override 注释时，我的 Logcat:

中出现错误

java.lang.UnsupportedOperationException: Required method instantiateItem was not overridden

如何为 PagerAdapter 中 CardView 上的按钮实现点击侦听器？

适配器代码：

public class CreateAdapter extends PagerAdapter {

private List<PdfPage> pagesList;
private LayoutInflater layoutInflater;
private Context context;
private onItemClickListener mListener;

public interface onItemClickListener{
    //click method for edit button
    void onEditClick(int position);
    //click method for delete button
    void onDeleteClick(int position);
}

public void setOnItemClickListener(onItemClickListener listener){
    mListener = listener;
}

public CreateAdapter(List<PdfPage> pagesList, Context context) {
    this.pagesList = pagesList;
    this.context = context;
}

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

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

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

    if(pagesList.get(position).getPageType() == "Text") {
        view = layoutInflater.inflate(R.layout.create_text_cardview, container, false);

        TextView inputText = view.findViewById(R.id.inputTextView);
        ImageButton editButton = view.findViewById(R.id.imageButtonEdit);
        ImageButton deleteButton = view.findViewById(R.id.imageButtonDelete);

        //if this works, see 12:30 of video for image getter
        inputText.setText(pagesList.get(position).getPageText());

        //edit click listener
        editButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (listener != null){
                    int position2 = pagesList.indexOf(pagesList.get(position));
                    listener.onEditClick(position2);
                }
            }
        });

        //delete click listener
        deleteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (listener != null){
                    int position3 = pagesList.indexOf(pagesList.get(position));
                    listener.onDeleteClick(position3);
                }
            }
        });

        container.addView(view, 0);

    }

    //put else statement here for image cardView

    assert view != null;
    return view;
}

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

Activity代码：

public class CreateActivity extends AppCompatActivity {

ViewPager viewPager;
CreateAdapter createAdapter;
List<PdfPage> pdfPageList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_create);

    pdfPageList = new ArrayList<>();
    
    createAdapter = new CreateAdapter(pdfPageList, this);

    viewPager = findViewById(R.id.viewPager);
    viewPager.setAdapter(createAdapter);
    viewPager.setPadding(130, 0, 130, 0);

}

@Override
protected void onStart() {
    super.onStart();

    createAdapter = new CreateAdapter(pdfPageList, this);

    viewPager = findViewById(R.id.viewPager);
    viewPager.setAdapter(createAdapter);
    viewPager.setPadding(130, 0, 130, 0);

    createAdapter.setOnItemClickListener(new CreateAdapter.onItemClickListener() {
        @Override
        public void onEditClick(int position) {

        }

        @Override
        public void onDeleteClick(int position) {
            pdfPageList.remove(position);
        }
    });
}

Answer 1

你的 instantiateItem 方法没有从它的超类中覆盖，因为你添加了一个额外的参数 final onItemClickListener listener.

由于您对所有条目使用相同的 clickListener 并将项目位置作为参数传递，我建议您在适配器构造函数中传递 onItemClickListener，或者通过

进行设置

public void setOnItemClickListener(onItemClickListener listener){
    mListener = listener;
}

适配器代码：

public class CreateAdapter extends PagerAdapter {

private List<PdfPage> pagesList;
private LayoutInflater layoutInflater;
private Context context;
private onItemClickListener mListener;

public interface onItemClickListener{
    //click method for edit button
    void onEditClick(int position);
    //click method for delete button
    void onDeleteClick(int position);
}

public void setOnItemClickListener(onItemClickListener listener){
    mListener = listener;
}

public CreateAdapter(List<PdfPage> pagesList, Context context) {
    this.pagesList = pagesList;
    this.context = context;
}

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

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

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

    if(pagesList.get(position).getPageType() == "Text") {
        view = layoutInflater.inflate(R.layout.create_text_cardview, container, false);

        TextView inputText = view.findViewById(R.id.inputTextView);
        ImageButton editButton = view.findViewById(R.id.imageButtonEdit);
        ImageButton deleteButton = view.findViewById(R.id.imageButtonDelete);

        //if this works, see 12:30 of video for image getter
        inputText.setText(pagesList.get(position).getPageText());

        //edit click listener
        editButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mlistener != null){
                    int position2 = pagesList.indexOf(pagesList.get(position));
                    mlistener.onEditClick(position2);
                }
            }
        });

        //delete click listener
        deleteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mlistener != null){
                    int position3 = pagesList.indexOf(pagesList.get(position));
                    mlistener.onDeleteClick(position3);
                }
            }
        });

        container.addView(view, 0);

    }

    //put else statement here for image cardView

    assert view != null;
    return view;
}

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

您的 Activity 代码可以保持原样。

将点击侦听器添加到 PagerAdpater CardViews 中的两个按钮

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