单击 RecyclerView 项目时，显示一个新的 Activity，其中包含有关该项目的信息

Question

我无法解决问题：我有 RecyclerView（联系人列表）。当我单击 ilem 时，它应该会显示一个新的 Activity，其中包含有关该项目的信息。我有代码，但我不明白为什么它不起作用。也许有人可以帮助我。提前致谢。我的适配器 class:

public class ContactAdapter extends RecyclerView.Adapter<ContactAdapter.ViewHolder> {
    private LayoutInflater layoutInflater;
    private List<Contact> contacts;
    private Context context;

    public ContactAdapter(Context context, List<Contact> contacts) {
        this.contacts = contacts;
        this.layoutInflater = LayoutInflater.from(context);
    }

    @NonNull
    @Override
    public ContactAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = layoutInflater.inflate(R.layout.list_item, parent, false);
        return new ViewHolder(view);
    }


    @Override
    public void onBindViewHolder(ContactAdapter.ViewHolder holder, final int position) {
        final Contact contact = contacts.get(position);
        holder.imageView.setImageResource(contact.getImage());
        holder.nameView.setText(contact.getName());
        holder.numberView.setText(contact.getNumber());


        holder.itemView.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                Intent intent = new Intent(view.getContext(), SecondActivity.class);
                intent.putExtra("image",contact.getImage());
                intent.putExtra("name", contact.getName());
                intent.putExtra("number", contact.getNumber());
                context.startActivity(intent);
            }
        });

    }

    @Override
    public int getItemCount() {
        return contacts.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        final ImageView imageView;
        final TextView nameView, numberView;

        ViewHolder(View view) {
            super(view);
            imageView = view.findViewById(R.id.image);
            nameView = view.findViewById(R.id.name);
            numberView = view.findViewById(R.id.number);
        }
    }
}

我的activityclass:

public class ListActivity extends AppCompatActivity {
private List<Contact> contactList = new ArrayList<>();
    private RecyclerView recyclerView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list);
        setInitialData();
        recyclerView = findViewById(R.id.list);
        ContactAdapter contactAdapter = new ContactAdapter(this, contactList);
        recyclerView.setAdapter(contactAdapter);
    }

    private void setInitialData() {

        contactList.add(new Contact(R.drawable.face, "Anna Anna", "358742596814"));
        contactList.add(new Contact(R.drawable.face, "Max Max", "358742596814"));
        contactList.add(new Contact(R.drawable.face, "David David", "358742596814"));
        contactList.add(new Contact(R.drawable.face, "James James", "358742596814"));
        contactList.add(new Contact(R.drawable.face, "Lidia Lidia", "358742596814"));
        contactList.add(new Contact(R.drawable.face, "Alice Alice", "358742596814"));
        contactList.add(new Contact(R.drawable.face, "Mark Mark", "358742596814"));
    }
}

第二 activity class:

public class SecondActivity extends AppCompatActivity {
    private ImageView imageView;
    private TextView textName;
    private TextView textNumber;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.secondary_activity);
        Intent intent = getIntent();
        String name = getIntent().getStringExtra("name");
        String number = getIntent().getStringExtra("number");
        imageView = findViewById(R.id.imageView);
        textName = findViewById(R.id.textName);
        textNumber = findViewById(R.id.textNumber);
        textNumber.setText(number);
        textName.setText(name);
    }
}

Answer 1

在这种情况下启动其他 activity 不是个好主意。看看 master - detail fragment

但是如果你真的需要启动SecondActivity，你应该像这样修改你的代码：

    @Override
    public void onBindViewHolder(ContactAdapter.ViewHolder holder, final int position) {
        final Contact contact = contacts.get(position);
        holder.imageView.setImageResource(contact.getImage());
        holder.nameView.setText(contact.getName());
        holder.numberView.setText(contact.getNumber());

        //remove holder.itemView.setOnClickListener

    }

    @Override
    public int getItemCount() {
        return contacts.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        final ImageView imageView;
        final TextView nameView, numberView;

        ViewHolder(View view) {
            super(view);
            imageView = view.findViewById(R.id.image);
            nameView = view.findViewById(R.id.name);
            numberView = view.findViewById(R.id.number);
            //Set listener here
            view.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                 final Contact contact = contacts.get(getAdapterPosition());
                 //Your code here
            }
        });
        }
    }
}

Answer 2

您从未在 ContactAdapter class 的构造函数中初始化 context 对象：

//the constructor
public ContactAdapter(Context context, List<Contact> contacts) {
     
    this.contacts = contacts;
    this.layoutInflater = LayoutInflater.from(context); 

    //add this 
    this.context = context;
}

此外，当您单击该项目时，会像这样初始化意图：

Intent intent = new Intent(context , SecondActivity.class);

而不是这个：

Intent intent = new Intent(view.getContext(), SecondActivity.class);

单击 RecyclerView 项目时，显示一个新的 Activity，其中包含有关该项目的信息

When clicking on the RecyclerView item, display a new Activity with information about this item

android

android-intent

android-recyclerview