java - RecyclerView 问题

Question

主 Activity .java

its my main java class

package com.example.shikhu.newpractice;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

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

    button = (Button) findViewById(R.id.button);

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            startActivity(new Intent(MainActivity.this,DisplayList.class));
        }
    });
 }
}

显示列表.java

package com.example.shikhu.newpractice;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class DisplayList extends AppCompatActivity {

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

    BackgroundTask backgroundTask = new BackgroundTask(DisplayList.this);
    backgroundTask.execute();
}
}

后台任务.java

package com.example.shikhu.newpractice;

import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;

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

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
 import java.util.ArrayList;


public class BackgroundTask extends AsyncTask<Void,Fruit,Void> {

String json_string = "http://192.168.1.18:8081/fruitinfo/get_fruit_details.php";

Context ctx;
Activity activity;
RecyclerView recyclerView;
RecyclerView.Adapter adapter;
RecyclerView.LayoutManager layoutManager;

ArrayList<Fruit> arrayList = new ArrayList<>();
public  BackgroundTask(Context ctx)
{
    this.ctx=ctx;
    activity = (Activity)ctx;
}



@Override
protected void onPreExecute() {

    recyclerView = (RecyclerView)activity.findViewById(R.id.recyclerview);
    layoutManager = new LinearLayoutManager(ctx);
    recyclerView.setLayoutManager(layoutManager);
    recyclerView.setHasFixedSize(true);
    adapter = new RecyclerAdapter(arrayList);
    recyclerView.setAdapter(adapter);
}

@Override
protected Void doInBackground(Void... params) {


    try{
        URL url = new URL(json_string);
        HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
        InputStream inputStream = httpURLConnection.getInputStream();
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
        StringBuilder stringBuilder = new StringBuilder();
        String line;

        while((line=bufferedReader.readLine())!=null)
        {
            stringBuilder.append(line + "\n");
        }

        httpURLConnection.disconnect();
        String json_string = stringBuilder.toString().trim();
        JSONObject jsonObject = new JSONObject(json_string);
        JSONArray jsonArray = jsonObject.getJSONArray("server_response");

        int count = 0;

        while (count<jsonArray.length())
        {
            JSONObject JO = jsonArray.getJSONObject(count);
            count++;

            Fruit fruit = new Fruit(JO.getString("name"),JO.getInt("calories"),JO.getDouble("fat"));
            publishProgress(fruit);
        }


        Log.d("JSON STRING",json_string);
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return null;
}

@Override
protected void onProgressUpdate(Fruit... values) {

    arrayList.add(values[0]);
    adapter.notifyDataSetChanged();
}

@Override
protected void onPostExecute(Void aVoid) {
    super.onPostExecute(aVoid);
}
}

回收适配器.java

 package com.example.shikhu.newpractice;

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

 import java.util.ArrayList;


 public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.RecyclerViewHolder> {

private static final int TYPE_HEAD = 0;
private  static  final int TYPE_LIST = 1;

ArrayList<Fruit> arrayList = new ArrayList<>();

public RecyclerAdapter(ArrayList<Fruit> arrayList)
{
    this.arrayList =arrayList;
}

@Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

    if (viewType == TYPE_HEAD)
    {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.header_layout,parent,false);
        RecyclerViewHolder recyclerViewHolder = new RecyclerViewHolder(view,viewType);
        return recyclerViewHolder;
    }
    else if (viewType == TYPE_LIST)
    {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_layout,parent,false);
        RecyclerViewHolder recyclerViewHolder = new RecyclerViewHolder(view,viewType);
        return recyclerViewHolder;
    }
    return null;
}

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

    if (holder.viewType == TYPE_LIST) {
        Fruit fruit = arrayList.get(position);
        holder.Name.setText(fruit.getName());
        holder.Calories.setText(Integer.toString(fruit.getCalories()));
        holder.Fat.setText(Double.toString(fruit.getFat()));
    }

}

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

public static class RecyclerViewHolder extends RecyclerView.ViewHolder
{
    TextView Name,Calories,Fat;
    int viewType;
    public RecyclerViewHolder(View v,int viewType)
    {
        super(v);
        if (viewType == TYPE_LIST) {
            Name = (TextView) v.findViewById(R.id.name);
            Calories = (TextView) v.findViewById(R.id.calories);
            Fat = (TextView) v.findViewById(R.id.fat);
            this.viewType = TYPE_LIST;
        }else if (viewType == TYPE_HEAD)
        {
            this.viewType = TYPE_HEAD;
        }

    }

    public int getItemViewType(int position)
    {
        if (position==0)

            return TYPE_HEAD;
            return TYPE_LIST;

    }
}
}

水果.java

package com.example.shikhu.newpractice;

public class Fruit {
private String name;
private int calories;
private Double fat;

public Fruit(String name,int calories,Double fat)
{
    this.setName(name);
    this.setCalories(calories);
    this.setFat(fat);
}

public String getName()
{
    return name;
}
public  void setName(String name)
{
    this.name=name;
}

public int getCalories()
{
    return calories;
}
public  void setCalories(int calories)
{
    this.calories=calories;
}

public Double getFat()
{
    return fat;
}
public  void setFat(Double fat)
{
    this.fat=fat;
}
}

行布局.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="75dp"
android:layout_marginRight="15dp"
android:layout_marginLeft="15dp"
android:weightSum="1">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:gravity="center_vertical"
    android:textStyle="bold"
    android:textSize="20dp"
    android:text="Name"
    android:id="@+id/name"
    android:layout_weight="0.39" />

<TextView
    android:layout_width="79dp"
    android:layout_height="match_parent"
    android:text="Calorie"
    android:gravity="center_vertical"
    android:textSize="20dp"
    android:textStyle="bold"
    android:id="@+id/calories"
    android:layout_marginLeft="40dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:text="Fat"
    android:gravity="center_vertical"
    android:textSize="20dp"
    android:textStyle="bold"
    android:id="@+id/fat"
    android:layout_weight="0.15"
    android:layout_marginLeft="60dp" />
    </LinearLayout>

Header_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="65dp"
android:background="?attr/colorPrimary">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:gravity="center_vertical"
    android:textStyle="bold"
    android:textSize="20dp"
    android:text="Name"
    android:id="@+id/name1"
    android:layout_weight="0.20"
    android:textColor="#ffffff"
    android:layout_marginLeft="10dp" />

<TextView
    android:layout_width="79dp"
    android:layout_height="match_parent"
    android:text="Calorie"
    android:gravity="center_vertical"
    android:textSize="20dp"
    android:textStyle="bold"
    android:id="@+id/calories1"
    android:layout_marginLeft="10dp"
    android:textColor="#ffffff"/>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:text="Fat"
    android:gravity="center_vertical"
    android:textSize="20dp"
    android:textStyle="bold"
    android:id="@+id/fat1"
    android:layout_weight="0.15"
    android:layout_marginLeft="60dp"
    android:textColor="#ffffff"/>

 </LinearLayout>

activity_display_list.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".DisplayList">

<android.support.v7.widget.RecyclerView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/recyclerview"></android.support.v7.widget.RecyclerView>

 </RelativeLayout>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.shikhu.newpractice.MainActivity">

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Display List"
    android:id="@+id/button"
    android:layout_centerVertical="true"
    android:layout_centerHorizontal="true" />
 </RelativeLayout>

我的输出

i dont know why it is showing text of textview rather the data fetched from database enter image description here

脚本

  <?php
   $host = "localhost";
   $user = "root";
   $pass = "";
   $db = "fruit";

   $con = mysqli_connect($host,$user,$pass,$db);

   $query= "select * from fruit_details;";

   $result = mysqli_query($con,$query);
   $response = array();

   while($row = mysqli_fetch_array($result))
    {
array_push($response,array('name'=>$row[0],'calories'=>$row[1],'fat'=>$row[2        ]));
  }

 mysqli_close($con);

 echo json_encode(array('server_response'=>$response));
 ?>

Answer 1

您的适配器总是返回 TYPE_HEAD 我认为这是错误的。

 @Override
public int getItemViewType(int position) {
    if (position == 0) {
        return TYPE_HEAD;
    } else {
        return TYPE_LIST;
    }

}