Android
Impaginazione in RecyclerView

introduzione

MainActivity.java

import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.widget.TextView;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private Toolbar toolbar;

    private TextView tvEmptyView;
    private RecyclerView mRecyclerView;
    private DataAdapter mAdapter;
    private LinearLayoutManager mLayoutManager;
    private int mStart=0,mEnd=20;
    private List<Student> studentList;
    private List<Student> mTempCheck;
    public static int pageNumber;
    public int total_size=0;


    protected Handler handler;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        pageNumber = 1;
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        tvEmptyView = (TextView) findViewById(R.id.empty_view);
        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
        studentList = new ArrayList<>();
        mTempCheck=new ArrayList<>();
        handler = new Handler();
        if (toolbar != null) {
            setSupportActionBar(toolbar);
            getSupportActionBar().setTitle("Android Students");

        }

        mRecyclerView.setHasFixedSize(true);
        mLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mAdapter = new DataAdapter(studentList, mRecyclerView);
        mRecyclerView.setAdapter(mAdapter);
        GetGroupData("" + mStart, "" + mEnd);
        mAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
            @Override
            public void onLoadMore() {
                if( mTempCheck.size()> 0) {
                    studentList.add(null);
                    mAdapter.notifyItemInserted(studentList.size() - 1);
                    int start = pageNumber * 20;
                    start = start + 1;
                    ++ pageNumber;
                    mTempCheck.clear();
                    GetData("" + start,""+ mEnd);
                }
            }
        });
    }

    public void GetData(final String LimitStart, final String LimitEnd) {
        Map<String, String> params = new HashMap<>();
        params.put("LimitStart", LimitStart);
        params.put("Limit", LimitEnd);
        Custom_Volly_Request jsonObjReq = new Custom_Volly_Request(Request.Method.POST,
                "Your php file link", params,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {
                        Log.d("ResponseSuccess",response.toString());
                        // handle the data from the servoce
                    }
                }, new Response.ErrorListener() {

            @Override
            public void onErrorResponse(VolleyError error) {
                VolleyLog.d("ResponseErrorVolly: " + error.getMessage());

            }});
       
    }
    // load initial data
    private void loadData(int start,int end,boolean notifyadapter) {
        for (int i = start; i <= end; i++) {
            studentList.add(new Student("Student " + i, "androidstudent" + i + "@gmail.com"));
            if(notifyadapter)
                mAdapter.notifyItemInserted(studentList.size());
        }
    }
}

OnLoadMoreListener.java

interfaccia pubblica OnLoadMoreListener {void onLoadMore (); }

DataAdapter.java

import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;

public class DataAdapter extends RecyclerView.Adapter {
    private final int VIEW_ITEM = 1;
    private final int VIEW_PROG = 0;

    private List<Student> studentList;

    // The minimum amount of items to have below your current scroll position
    // before loading more.
    private int visibleThreshold = 5;
    private int lastVisibleItem, totalItemCount;
    private boolean loading;
    private OnLoadMoreListener onLoadMoreListener;



    public DataAdapter(List<Student> students, RecyclerView recyclerView) {
        studentList = students;
        if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {
            final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
                    recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
                        @Override
                        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                            super.onScrolled(recyclerView, dx, dy);
                            totalItemCount = linearLayoutManager.getItemCount();
                            lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
                            if (! loading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                                if (onLoadMoreListener != null) {
                                    onLoadMoreListener.onLoadMore();
                                }
                                loading = true;
                            }
                        }
                    });
        }
    }

    @Override
    public int getItemViewType(int position) {

            return studentList.get(position) != null ? VIEW_ITEM : VIEW_PROG;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        RecyclerView.ViewHolder vh;
        if (viewType == VIEW_ITEM) {
            View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_row, parent, false);
            vh = new StudentViewHolder(v);
        } else {
            View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.progress_item, parent, false);
            vh = new ProgressViewHolder(v);
        }
        return vh;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof StudentViewHolder) {
            Student singleStudent=studentList.get(position);
            ((StudentViewHolder) holder).tvName.setText(singleStudent.getName());
            ((StudentViewHolder) holder).tvEmailId.setText(singleStudent.getEmailId());
            ((StudentViewHolder) holder).student= singleStudent;
        } else {
            ((ProgressViewHolder) holder).progressBar.setIndeterminate(true);
        }
    }

    public void setLoaded(boolean state) {
        loading = state;
    }

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

    public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
        this.onLoadMoreListener = onLoadMoreListener;
    }


    //
    public static class StudentViewHolder extends RecyclerView.ViewHolder {
        public TextView tvName;
        
        public TextView tvEmailId;
        
        public Student student;

        public StudentViewHolder(View v) {
            super(v);
            tvName = (TextView) v.findViewById(R.id.tvName);
            tvEmailId = (TextView) v.findViewById(R.id.tvEmailId);

            
        }
    }

    public static class ProgressViewHolder extends RecyclerView.ViewHolder {
        public ProgressBar progressBar;

        public ProgressViewHolder(View v) {
            super(v);
            progressBar = (ProgressBar) v.findViewById(R.id.progressBar1);
        }
    }

}