Question

我试图保存我的arraylist＆＃34;人员＆＃34;在onSaveInstanceState中，然后在我切换方向时在create（）中恢复它。通过日志，我看到人们恢复了，但适配器没有显示人员的屏幕项目！不幸的是，我不明白如何解决它。有人可以帮忙吗？

import android.content.Intent;
import android.os.Bundle;
import android.os.PersistableBundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.CardView;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private List<Person> persons;
    private RecyclerView rv;
    final String LOG_TAG = "myLogs";
    RVAdapter adapter;
    Person person;
    ProductCardList mProductCard;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        rv = (RecyclerView)findViewById(R.id.rv);
        rv.setHasFixedSize(true);
        LinearLayoutManager llm = new LinearLayoutManager(this);
        rv.setLayoutManager(llm);
        persons = new ArrayList<>();
        adapter = new RVAdapter(persons);
        rv.setAdapter(adapter);



        if ((savedInstanceState != null) && (savedInstanceState.getSerializable("card") != null)) {
                persons = (List<Person>) savedInstanceState.getSerializable("card");
                adapter.notifyDataSetChanged();
                Log.d(LOG_TAG, "restore card with persons" + persons);
                }



        adapter.setOnItemClickListener(new RVAdapter.MyClickListener() {
            @Override
            public void onItemClick(int position, View v) {
                Toast.makeText(MainActivity.this, "push on item" + position, Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(MainActivity.this, ProductCard.class);
                startActivity(intent);
            }
        });


        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               person= new Person("Emma Wilson", "23 years old", R.drawable.im_beach);
               persons.add(person);
               Log.d(LOG_TAG, "push add" + persons);
               adapter.notifyDataSetChanged();
            }
        });

    }


       @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putSerializable("card", (Serializable) persons);
        Log.d(LOG_TAG, "save cards" + persons);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {

            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

我的适配器

import android.support.v7.widget.CardView;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

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

/**
 * Created by Dmitry on 01.11.2015.
 */
public class RVAdapter extends RecyclerView.Adapter<RVAdapter.PersonViewHolder>{
    List<Person> persons;
    private static String LOG_TAG = "MyRecyclerViewAdapter";
    private static MyClickListener myClickListener;
    RVAdapter(List<Person> persons){
        this.persons = persons;
    }
    @Override
    public PersonViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.card, viewGroup, false);
        PersonViewHolder pvh = new PersonViewHolder(v);
        return pvh;
    }

    @Override
    public void onBindViewHolder(PersonViewHolder personViewHolder, int i) {
        personViewHolder.personName.setText(persons.get(i).name);
        personViewHolder.personAge.setText(persons.get(i).age);
        personViewHolder.personPhoto.setImageResource(persons.get(i).photoId);
    }

    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
    }

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

    public static class PersonViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        CardView cv;
        TextView personName;
        TextView personAge;
        ImageView personPhoto;
        PersonViewHolder(View itemView) {
            super(itemView);
            cv = (CardView)itemView.findViewById(R.id.cv);
            personName = (TextView)itemView.findViewById(R.id.person_name);
            personAge = (TextView)itemView.findViewById(R.id.person_age);
            personPhoto = (ImageView)itemView.findViewById(R.id.person_photo);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {
            myClickListener.onItemClick(getAdapterPosition(), v);
        }
    }

    public void setOnItemClickListener(MyClickListener myClickListener) {
        this.myClickListener = myClickListener;
    }
    public interface MyClickListener {
        public void onItemClick(int position, View v);
    }

}

更新部分

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        rv = (RecyclerView)findViewById(R.id.rv);
        rv.setHasFixedSize(true);
        LinearLayoutManager llm = new LinearLayoutManager(this);
        rv.setLayoutManager(llm);
        persons = new ArrayList<>();
        adapter = new RVAdapter(persons);
        rv.setAdapter(adapter);



        if ((savedInstanceState != null) && (savedInstanceState.getSerializable("card") != null)) {
                persons = (List<Person>) savedInstanceState.getSerializable("card");
                adapter = new RVAdapter(persons);
                rv.setAdapter(adapter);
                adapter.notifyDataSetChanged();
                Log.d(LOG_TAG, "restore card with persons" + persons);
                }

Answer 1

您没有将反序列化人员列表传递给适配器。您正在替换人员实例，而不是更新列表本身。

移动：

adapter = new RVAdapter(persons);
rv.setAdapter(adapter);

阅读savedInstanceState。

或者做这样的事情：

persons = new ArrayList<>();
adapter = new RVAdapter(persons);
rv.setAdapter(adapter);

if (savedInstanceState != null && savedInstanceState.getSerializable("card") != null) {
     persons.clear();         
     persons.addAll((List<Person>) savedInstanceState.getSerializable("card"));
     adapter.notifyDataSetChanged();
     Log.d(LOG_TAG, "restore card with persons" + persons);
}

适配器不显示项目

1 个答案: