android - RecyclerView 之间的距离太远

Question

目前是 android 开发的初学者，我一直在这里和那里进行一些练习/教程，我遇到了一个问题，即 RecyclerView 中的项目之间的距离彼此相距太远，如下图所示.我如何使它们彼此更接近？我一直在搜索，但没有任何效果。

编辑:将 android:layout_height = "match_parent" 更改为 android:layout_height = "wrap_content" 后仍然没有变化布局。

所以我包含了我的java类

RecyclerView Screenshot

这是我的.xml

custom_row_news_items.xml

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceSmall"
        android:text="Small Text"
        android:id="@+id/date_text"
        android:layout_alignParentTop="true"
        android:layout_alignParentEnd="true" />

    <ImageView
        android:src="@drawable/img"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/thumb_img"
        android:layout_below="@+id/date_text"
        android:layout_centerHorizontal="true" />

    <TextView
        android:background="#006699"
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Large Text"
        android:id="@+id/title_text"
        android:layout_alignBottom="@+id/thumb_img"
        android:layout_centerHorizontal="true" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Medium Text"
        android:id="@+id/des_text"
        android:layout_below="@+id/thumb_img"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

content_navigation_drawer.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"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/app_bar_navigation_drawer"
tools:context="com.example.azrie.dummyvoicethenews.NavigationDrawer">

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

这是我的 java 类

NavigationDrawer.java

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;

public class NavigationDrawer extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

   RecyclerView recyclerView;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_navigation_drawer);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
        this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
    RSSread rssRead;
    rssRead = new RSSread(this,recyclerView);
    rssRead.execute();
}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

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

@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);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_camera) {
        // Handle the camera action
    } else if (id == R.id.nav_gallery) {

    } else if (id == R.id.nav_slideshow) {

    } else if (id == R.id.nav_manage) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
    }
}

RSSread.java

public class RSSread extends AsyncTask{

Context context;
ProgressDialog progressDialog;
//RSS address
String address = "https://www.sciencemag.org/rss/news_current.xml";
URL url;
//Global initialization for other class to access
ArrayList<FeedItem> feedItems;
RecyclerView recyclerView;

public RSSread(Context context, RecyclerView recyclerView){
    //Initialize recycle view
    this.recyclerView = recyclerView;
    //Initialize progress dialog
    this.context = context;
    progressDialog = new ProgressDialog(context);
    progressDialog.setMessage("Loading....");
}

@Override
protected void onPreExecute() {
    //display progress dialog before fetching data
    progressDialog.show();
    super.onPreExecute();
}

@Override
protected void onPostExecute(Object o) {
    super.onPostExecute(o);
    //dismiss the "Loading..." progress dialog
    progressDialog.dismiss();
    MyAdapter adapter = new MyAdapter(context,feedItems);
    recyclerView.setLayoutManager(new LinearLayoutManager(context));
    recyclerView.setAdapter(adapter);
}

@Override
protected Object doInBackground(Object[] objects) {
    ProcessXml(Getdata()); 
    return null;
}

private void ProcessXml(Document data) {
    //If data is present or not = null
    if(data!=null){
        //ArrayList is created to store every item into a single item
        feedItems = new ArrayList<>();
        //Return document element name that is RSS ( Exercise Part 1 )
        //Log.d("Root", data.getDocumentElement().getNodeName());
        //Element object that store "Root" element
        Element root = data.getDocumentElement();
        //Items are inside channel and channel tag is first child of root tag
        Node channel = root.getChildNodes().item(1);
        //Store all child of channel element
        NodeList items = channel.getChildNodes();

        //Loop through each child of element
        //Output testing
        //Log.d("ItemsLength",Integer.toString(items.getLength()));
        for (int i = 0; i < items.getLength(); i++){
            //Create new node that will store data
            Node currentChild = items.item(i);

            //Check currentChild node is item node
            if (currentChild.getNodeName().equalsIgnoreCase("item")){
                //Create a new feed item for every item
                FeedItem item = new FeedItem(); //Exercise Part 2 : How to process data
                NodeList itemChild = currentChild.getChildNodes();

                //Loop through all childs with item tag
                for(int j = 0; j < itemChild.getLength(); j++){
                    Node current = itemChild.item(j);
                    //Display context of Node Current ( Exercise Part 1 : How to process data )
                    //Log.d("textContent",current.getTextContent());

                    //check for node title node
                    if(current.getNodeName().equalsIgnoreCase("title")){
                        //Set title from FeedItem into current title
                        item.setTitle(current.getTextContent());
                        //Output test
                        Log.d("CurrentItemTitle",current.getTextContent());
                    }

                    else if(current.getNodeName().equalsIgnoreCase("description")){
                        //Set description from FeedItem into current description
                        item.setDescr(current.getTextContent());
                        //Output test
                        Log.d("CurrentItemDesp",current.getTextContent());

                    }

                    else if(current.getNodeName().equalsIgnoreCase("pubDate")){
                        //Set pubDate from FeedItem into current pubDate
                        item.setPubDate(current.getTextContent());
                        //Output test
                        Log.d("CurrentItemPubDate",current.getTextContent());

                    }

                    else if(current.getNodeName().equalsIgnoreCase("link")){
                        //Set link from FeedItem into current link
                        item.setLink(current.getTextContent());
                        //Output test
                        Log.d("CurrentItemLink",current.getTextContent());

                    }

                    else if(current.getNodeName().equalsIgnoreCase("media:thumbnail")){
                        String url = current.getAttributes().item(0).getTextContent();
                        item.setThumbnailUrl(url);
                        //Output test
                        Log.d("CurrentItemThumbnailUrl",current.getTextContent());

                    }
                }

                feedItems.add(item);
                Log.d("ItemTitle",item.getTitle());
                Log.d("ItemDescription",item.getDescr());
                Log.d("ItemLink",item.getLink());
                Log.d("ItemPubDate",item.getPubDate());
                Log.d("ItemThumbnailUrl",item.getThumbnailUrl());

            }
        }
    }
}

//method that return Document type
public Document Getdata(){

    try {
        //Passing the string to URL (From Address)
        url = new URL(address);
        //Open connection
        HttpURLConnection connection;
        connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");
        InputStream inputStream = connection.getInputStream();
        //Create new instance of document build
        DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = builderFactory.newDocumentBuilder();
        //Return XML document
        Document xmlDoc = builder.parse(inputStream);
        //Return xmlDoc
        return xmlDoc;

    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }

}

}

MyAdapter.java

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
ArrayList<FeedItem> feedItems;
Context context;

public MyAdapter(Context context,ArrayList<FeedItem> feedItems){
    this.feedItems = feedItems;
    this.context = context;
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(context).inflate(R.layout.custom_row_news_items,parent,false);
    MyViewHolder holder = new MyViewHolder(view);
    return holder;
}

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

}

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

public class MyViewHolder extends RecyclerView.ViewHolder {
    public MyViewHolder(View itemView) {
        super(itemView);
    }
}
}

抱歉有点乱。我还是不习惯这里的格式。

Answer 1

在custom_row_news_items.xml中，android:layout_height="match_parent"应该是android:layout_height="wrap_content。因为match_parent，它占用了整个屏幕。始终记住，如果 recyclerview 具有垂直布局，则单行的高度应为 wrap_content。

也可以尝试将recyclerview的高宽参数改成

    android:layout_width="match_parent"
    android:layout_height="match_parent"

我推测，因为您的高度设置为包裹内容，所以它只占一行。但是有了 match_parent，它将在屏幕上容纳尽可能多的内容。