java - 我想在TabLayout中按 fragment 更改RecyclerView列表数据

Question

我想在TabLayout中按 fragment 更改RecyclerView列表数据。 我想删除旧数据，并将我自己的数据放入应用程序中， 我是新来的，所以我不知道如何删除以及如何放置新数据

主要 Activity :

package baleli.urdupoetrybytariq;

import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private static Toolbar toolbar;
    private static ViewPager viewPager;
    private static TabLayout tabLayout;

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

        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        viewPager = (ViewPager) findViewById(R.id.viewPager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabLayout);
        tabLayout.setupWithViewPager(viewPager);//setting tab over viewpager

        //Implementing tab selected listener over tablayout
        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());//setting current selected item over viewpager
                switch (tab.getPosition()) {
                    case 0:
                        Log.e("TAG","TAB1");
                        break;
                    case 1:
                        Log.e("TAG","TAB2");
                        break;
                    case 2:
                        Log.e("TAG","TAB3");
                        break;
                }
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {
            }
        });
    }


    //Setting View Pager
    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFrag(new DummyFragment("Item"), "Love Poetry");
        adapter.addFrag(new DummyFragment("Item"), "Bewafa Poetry");
        adapter.addFrag(new DummyFragment("Item"), "Sad Poetry");
        viewPager.setAdapter(adapter);
    }


    //View Pager fragments setting adapter class
    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();//fragment arraylist
        private final List<String> mFragmentTitleList = new ArrayList<>();//title arraylist

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

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


        //adding fragments and title method
        public void addFrag(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
}

Recyclerview_Adapter:

package baleli.urdupoetrybytariq;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.ViewGroup;

import java.util.ArrayList;

/**
 * Created by SONU on 10/09/15.
 */
public class RecyclerView_Adapter extends
        RecyclerView.Adapter<DemoViewHolder> {
    private ArrayList<String> arrayList;
    private Context context;


    public RecyclerView_Adapter(Context context,
                                ArrayList<String> arrayList) {
        this.context = context;
        this.arrayList = arrayList;

    }


    @Override
    public int getItemCount() {
        return (null != arrayList ? arrayList.size() : 0);

    }

    @Override
    public void onBindViewHolder(DemoViewHolder holder,
                                 int position) {


        final DemoViewHolder mainHolder = (DemoViewHolder) holder;
        //Setting text over textview
        mainHolder.title.setText(arrayList.get(position));

    }

    @Override
    public DemoViewHolder onCreateViewHolder(
            ViewGroup viewGroup, int viewType) {
        LayoutInflater mInflater = LayoutInflater.from(viewGroup.getContext());

        ViewGroup mainGroup = (ViewGroup) mInflater.inflate(
                R.layout.item_row, viewGroup, false);
        DemoViewHolder mainHolder = new DemoViewHolder(mainGroup) {
            @Override
            public String toString() {
                return super.toString();
            }
        };


        return mainHolder;

    }


}

虚拟 fragment :

package baleli.urdupoetrybytariq;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;

import baleli.urdupoetrybytariq.R;

/**
 * Created by SONU on 16/09/15.
 */
public class DummyFragment extends Fragment {
    private View view;

    private String title;//String for tab title

    private static RecyclerView recyclerView;

    public DummyFragment() {
    }

    public DummyFragment(String title) {
        this.title = title;//Setting tab title
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.dummy_fragment, container, false);

        setRecyclerView();
        return view;

    }
    //Setting recycler view
    private void setRecyclerView() {

        recyclerView = (RecyclerView) view
                .findViewById(R.id.recyclerView);
        recyclerView.setHasFixedSize(true);
        recyclerView
                .setLayoutManager(new LinearLayoutManager(getActivity()));//Linear Items


        ArrayList<String> arrayList = new ArrayList<>();
        for (int i = 0; i < 50; i++) {
            arrayList.add(title+"" + i);//Adding items to recycler view
        }
        RecyclerView_Adapter adapter = new RecyclerView_Adapter(getActivity(), arrayList);
        recyclerView.setAdapter(adapter);// set adapter on recyclerview

    }
}

DemoViewHolder:

package baleli.urdupoetrybytariq;

import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

/**
 * Created by SONU on 31/08/15.
 */
public abstract class DemoViewHolder extends RecyclerView.ViewHolder {


    public TextView title;


    public DemoViewHolder(View view) {
        super(view);


        this.title = (TextView) view.findViewById(R.id.cardTitle);

    }


}

Answer 1

这里您使用循环将数据插入到ArrayList中。

将您的以下代码更改为我的代码:

DummyFragment.java:

您的代码:

 ArrayList<String> arrayList = new ArrayList<>();
        for (int i = 0; i < 20; i++) {
            arrayList.add(title+" Items " + i);//Adding items to recycler view
        }

更改为以下代码:

 ArrayList<String> arrayList = new ArrayList<>();
        arrayList.add("First Data");
        arrayList.add("Second Data");
        arrayList.add("Third Data");
        arrayList.add("Fourth Data");
        arrayList.add("Fifth Data");
        arrayList.add("Sixth Data"); //As like your can insert data to your ArrayList.