Einfaches Android Grid-Beispiel mit RecyclerView und GridLayoutManager (wie das alte GridView)

Obwohl ich die Antwort von Suragch mag und schätze, möchte ich eine Notiz hinterlassen, weil ich Es wurde festgestellt, dass die Codierung des Adapters (MyRecyclerViewAdapter) zum Definieren und Anzeigen der Listener-Methode onItemClick nicht die beste Methode ist Es liegt daran, dass die Klassenkapselung nicht korrekt verwendet wird. Mein Vorschlag ist also, den Adapter ausschließlich die Listening-Operationen ausführen zu lassen (das ist sein Zweck!) Und diese von der Aktivität zu trennen, die den Adapter (MainActivity). So würde ich die Adapter-Klasse einstellen:

MyRecyclerViewAdapter.Java

public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ViewHolder> {

    private String[] mData = new String[0];
    private LayoutInflater mInflater;

    // Data is passed into the constructor
    public MyRecyclerViewAdapter(Context context, String[] data) {
        this.mInflater = LayoutInflater.from(context);
        this.mData = data;
    }

    // Inflates the cell layout from xml when needed
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mInflater.inflate(R.layout.recyclerview_item, parent, false);
        ViewHolder viewHolder = new ViewHolder(view);
        return viewHolder;
    }

    // Binds the data to the textview in each cell
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        String animal = mData[position];
        holder.myTextView.setText(animal);
    }

    // Total number of cells
    @Override
    public int getItemCount() {
        return mData.length;
    }

    // Stores and recycles views as they are scrolled off screen
    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public TextView myTextView;

        public ViewHolder(View itemView) {
            super(itemView);
            myTextView = (TextView) itemView.findViewById(R.id.info_text);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View view) {
            onItemClick(view, getAdapterPosition());
        }
    }

    // Convenience method for getting data at click position
    public String getItem(int id) {
        return mData[id];
    }

    // Method that executes your code for the action received
    public void onItemClick(View view, int position) {
        Log.i("TAG", "You clicked number " + getItem(position).toString() + ", which is at cell position " + position);
    }
}

Bitte beachten Sie die onItemClick -Methode, die jetzt in MyRecyclerViewAdapter definiert ist. Dies ist der Ort, an dem Sie Ihre Aufgaben für das empfangene Ereignis/die empfangene Aktion codieren möchten.

Es ist nur eine kleine Änderung erforderlich, um diese Transformation abzuschließen: Die Aktivität muss MyRecyclerViewAdapter.ItemClickListener nicht mehr implementieren, da das erledigt jetzt komplett der Adapter . Dies wäre dann die letzte Änderung:

MainActivity.Java

public class MainActivity extends AppCompatActivity {

    MyRecyclerViewAdapter adapter;

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

        // data to populate the RecyclerView with
        String[] data = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48"};

        // set up the RecyclerView
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.rvNumbers);
        int numberOfColumns = 6;
        recyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));
        adapter = new MyRecyclerViewAdapter(this, data);
        adapter.setClickListener(this);
        recyclerView.setAdapter(adapter);
    }
}

Quelle der mittleren Richtlinie

GitHub repo

Fügen Sie die RecyclerView-Abhängigkeit in build.gradle hinzu

compile 'com.Android.support:recyclerview-v7:25.1.1'

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:Android="http://schemas.Android.com/apk/res/Android"
    xmlns:tools="http://schemas.Android.com/tools"
    Android:id="@+id/activity_main"
    Android:layout_width="match_parent"
    Android:layout_height="match_parent"
    >

    <!--TODO(2): RecyclerView inside FrameLayout-->

    <Android.support.v7.widget.RecyclerView
        Android:id="@+id/rvStudents"
        Android:layout_width="match_parent"
        Android:layout_height="match_parent"
        Android:scrollbars="none"
        >
    </Android.support.v7.widget.RecyclerView>

    <!--TODO(3): Create one layout resource with item_student.xml name-->

</FrameLayout>

item_student.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:Android="http://schemas.Android.com/apk/res/Android"
    Android:orientation="vertical" Android:layout_width="match_parent"
    Android:layout_height="wrap_content"
    Android:background="#d2d2d2"
    Android:id="@+id/llItemStudents"
    Android:layout_margin="8dp"
    >

    <!--TODO(4): Remember to change the height of LinearLayout to wrap_content and also add its ID-->

    <!--TODO(5): Add two TextView which will display student name and mobile number respectively-->

    <TextView
        Android:id="@+id/tvStudentName"
        Android:layout_width="wrap_content"
        Android:layout_height="wrap_content"
        Android:layout_margin="8dp"
        Android:padding="8dp"
        Android:textSize="25sp"
        Android:textStyle="bold"
        Android:textColor="@color/colorPrimary"
        />

    <TextView
        Android:id="@+id/tvMobileNumber"
        Android:layout_width="wrap_content"
        Android:layout_height="wrap_content"
        Android:layout_margin="8dp"
        Android:padding="8dp"
        Android:textSize="22sp"
        Android:textStyle="bold"
        Android:textColor="@color/colorAccent"
        />

</LinearLayout>

MainActivity.Java

import Android.support.v7.app.AppCompatActivity;
import Android.os.Bundle;
import Android.support.v7.widget.GridLayoutManager;
import Android.support.v7.widget.LinearLayoutManager;
import Android.support.v7.widget.RecyclerView;
import Android.support.v7.widget.StaggeredGridLayoutManager;
import Android.text.Layout;

import Java.util.ArrayList;

/*
 * Demo Code of Recycler View
 * Created on: 19th Feb, 2017
 * Author Name: Rajat Talesra
 * Company Name: WiseL
 * This code is for Android Monk Campus Program.
 */

/*
 * Recycler View is mainly used to show dynamic list of data.
 * Many applications including Whatsapp, Facebook, Gmail, etc. used RecyclerView
 *
 * RecyclerView mainly uses two main components LayoutManager and Adapter
 *
 * LayoutManger: Helps to arrange data in LinearLayout or GridLayout
 *
 * Adapter: Helps to connect our recycler view with the custom layout and display data on screen
 *
 * In this demo we will display students list with their names and mobile numbers.
 */

public class MainActivity extends AppCompatActivity {

    //TODO(6): Create arrayList for student names and ids.

    ArrayList<String> namesArrayList = new ArrayList<>();
    ArrayList<String> mobileArrayList = new ArrayList<>();

    //TODO(7): Declare below mentioned components.

    RecyclerView rvStudentsList;
    RecyclerView.LayoutManager rvLayoutManager;

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

        //TODO(10): Add data to arrayList
        namesArrayList.add("Student 1");
        namesArrayList.add("Student 2");
        namesArrayList.add("Student 3");
        namesArrayList.add("Student 4");
        namesArrayList.add("Student 5");
        namesArrayList.add("Student 6");
        namesArrayList.add("Student 7");
        namesArrayList.add("Student 8");
        namesArrayList.add("Student 9");
        namesArrayList.add("Student 10");

        mobileArrayList.add("8766986401");
        mobileArrayList.add("8766986402");
        mobileArrayList.add("8766986403");
        mobileArrayList.add("8766986404");
        mobileArrayList.add("8766986405");
        mobileArrayList.add("8766986406");
        mobileArrayList.add("8766986407");
        mobileArrayList.add("8766986408");
        mobileArrayList.add("8766986409");
        mobileArrayList.add("8766986410");

        //TODO(9): Connect UI elements with Java objects.
        rvStudentsList = (RecyclerView) findViewById(R.id.rvStudents);


        //User this to display items vertically
        //rvLayoutManager = new LinearLayoutManager(this);

        //User this to display items in Grid Layout with 2 columns
        rvLayoutManager = new GridLayoutManager(this,2);

        //TODO(10): Attach layoutManager to recycler view
        rvStudentsList.setLayoutManager(rvLayoutManager);

        /*
         * Now we need to create one adapter, so that we can display data row wise
         * For this we will create our custom adapter, i.e. StudentAdapter.Java
         */

        //TODO(11): Create new Java class StudentAdapter.Java

        //TODO(16): Pass data to our custom adapter
        StudentAdapter studentAdapter = new StudentAdapter(this,namesArrayList,mobileArrayList);

        //TODO(17): Attach studentAdapter to recycler view

        rvStudentsList.setAdapter(studentAdapter);

        //TODO(18): Run your app.

    }
}

StudentAdapter.Java

import Android.content.Context;
import Android.support.v7.widget.RecyclerView;
import Android.view.LayoutInflater;
import Android.view.View;
import Android.view.ViewGroup;
import Android.widget.LinearLayout;
import Android.widget.TextView;
import Android.widget.Toast;

import Java.util.ArrayList;

//TODO(12): StudentAdapter extends RecyclerView Adapter with ViewHolder class


public class StudentAdapter extends RecyclerView.Adapter<StudentAdapter.ViewHolder> {

    //TODO(13): Create two empty arrayList and one context variable;

    Context mainActivityContext;
    ArrayList<String> namesArrayList = new ArrayList<>();
    ArrayList<String> mobileArrayList = new ArrayList<>();

    //TODO(14): Create one constructor with three parameters which will passed from MainActivity class

    public StudentAdapter(Context mainActivityContext, ArrayList<String> namesArrayList, ArrayList<String> mobileArrayList) {
        this.mainActivityContext = mainActivityContext;
        this.namesArrayList = namesArrayList;
        this.mobileArrayList = mobileArrayList;
    }

    //TODO(15): Complete each method as mentioned below


    @Override
    public StudentAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        //Used to connect our custom UI to our recycler view

        View v = LayoutInflater
                .from(parent.getContext())
                .inflate(R.layout.item_student, parent, false);

        return new ViewHolder(v);
    }

    @Override
    public void onBindViewHolder(StudentAdapter.ViewHolder holder, int position) {
        //Used to set data in each row of recycler view

        String currentName = namesArrayList.get(position);
        String currentMobileNumber = mobileArrayList.get(position);

        holder.tvName.setText(currentName);
        holder.tvMobileNumber.setText(currentMobileNumber);

    }

    @Override
    public int getItemCount() {
        //Returns total number of rows inside recycler view

        return namesArrayList.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        //Used to work with the elements of our custom UI.

        LinearLayout llItemStudents;

        TextView tvName;
        TextView tvMobileNumber;

        public ViewHolder(View itemView) {
            super(itemView);

            tvName = (TextView) itemView.findViewById(R.id.tvStudentName);
            tvMobileNumber = (TextView) itemView.findViewById(R.id.tvMobileNumber);

            llItemStudents = (LinearLayout) itemView.findViewById(R.id.llItemStudents);

            llItemStudents.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Toast.makeText(mainActivityContext,
                            "You clicked item number: "+ getAdapterPosition(),
                            Toast.LENGTH_SHORT).show();
                }
            });

        }
    }
}

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