Warum funktioniert dieses RecyclerView + CardView-Beispiel nicht?

Question

Ich versuche, eine App mit einer Liste von Lebensmitteln auf der Haupttätigkeit und einem Kontrollkästchen für jedes Essen zu erstellen.

folgte ich dieses Tutorial, um den gesamten Text und Kontrollkästchen, was zu tun: http://android-pratap.blogspot.co.il/2015/01/recyclerview-with-checkbox-example.html

Aber immer, wenn ich die app laufen sie einfach nicht die RecyclerView auf dem Hauptbildschirm zeigen ... (Die App läuft , aber der RecyclerView ist einfach nicht da)

Wenn jemand erklären kann, wie ich meinen Code ändern kann, so würde es nicht die Karten erfordern, die fantastisch wären. Hier ist mein Code:

MainAcitivity.java: (Just kombiniert die RecyclerView mit dem FoodAdapter)

package com.gregskl.foodreminder; 

import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
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.view.View; 
import android.view.Menu; 
import android.view.MenuItem; 

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

public class MainActivity extends AppCompatActivity { 

    private RecyclerView recycler; 
    private RecyclerView.Adapter adapter; 

    private List<Food> foods; 

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

     foods = new ArrayList<>(); 
     foods.add(new Food("Grapes", true)); 
     foods.add(new Food("Oranges", true)); 

     recycler = (RecyclerView) findViewById(R.id.recycler); 
     recycler.setLayoutManager(new LinearLayoutManager(this)); 
     adapter = new FoodAdapater(foods); 
     recycler.setAdapter(adapter); 

     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(); 
      } 
     }); 
    } 

    @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 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); 
    } 
} 

FoodAdapter.java:

package com.gregskl.foodreminder; 

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

import java.util.List; 

/** 
* Created by Gregory on 11-Sep-16. 
*/ 
public class FoodAdapater extends RecyclerView.Adapter<FoodAdapater.ViewHolder> { 

    private List<Food> foods; 

    public FoodAdapater(List<Food> foods) { 
     this.foods = foods; 
    } 

    @Override 
    public FoodAdapater.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
     View itemLayoutView = LayoutInflater.from(parent.getContext()).inflate(R.layout.list, null); 
     return new ViewHolder(itemLayoutView); 
    } 

    @Override 
    public void onBindViewHolder(FoodAdapater.ViewHolder holder, int position) { 
     ViewHolder h = (ViewHolder) holder; 
     h.text.setText(foods.get(position).getText()); 
     h.checkbox.setChecked(foods.get(position).isAvailable()); 
     h.checkbox.setTag(foods.get(position)); 
     h.checkbox.setOnClickListener(new View.OnClickListener() { 
      public void onClick(View v) { 
       Toast.makeText(v.getContext(), "Hey", Toast.LENGTH_LONG).show(); 
      } 
     }); 
    } 

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

    public static class ViewHolder extends RecyclerView.ViewHolder { 

     public TextView text; 
     public CheckBox checkbox; 

     public ViewHolder(View itemView) { 
      super(itemView); 
      text = (TextView) itemView.findViewById(R.id.text); 
      checkbox = (CheckBox) itemView.findViewById(R.id.checkbox); 
     } 
    } 
} 

Food.java: (Das Datenmodell für das Essen)

package com.gregskl.foodreminder; 

/** 
* Created by Gregory on 11-Sep-16. 
*/ 
public class Food { 

    private String text; 
    private boolean available; 

    public Food(String text, boolean available) { 
     this.text = text; 
     this.available = available; 
    } 

    public String getText() { 
     return text; 
    } 

    public boolean isAvailable() { 
     return available; 
    } 

    public void setText(String text) { 
     this.text = text; 
    } 

    public void setAvailable(boolean available) { 
     this.available = available; 
    } 
} 

content_main.xml:

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    app:layout_behavior="@string/appbar_scrolling_view_behavior" 
    tools:context="com.gregskl.foodreminder.MainActivity" 
    tools:showIn="@layout/activity_main"> 

    <android.support.v7.widget.RecyclerView 
     android:id="@+id/recycler" 
     android:layout_width="match_parent" 
     android:layout_height="0dp" 
     android:layout_margin="5dp" 
     android:layout_weight="1" 
     android:scrollbars="vertical" /> 

</RelativeLayout> 

list.xml:

<?xml version="1.0" encoding="utf-8"?> 
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:card_view="http://schemas.android.com/apk/res-auto" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:orientation="horizontal" 
    card_view:cardCornerRadius="5dp" 

    card_view:cardUseCompatPadding="true" > 

    <RelativeLayout 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_margin="5dp" > 

     <TextView 
      android:id="@+id/text" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:layout_alignParentTop="true" 
      android:text="name" 
      android:textColor="@android:color/black" 
      android:textSize="18sp" /> 
     <CheckBox 
      android:id="@+id/checkbox" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_alignParentRight="true" 
      android:layout_centerVertical="true" 
      /> 
    </RelativeLayout> 

</android.support.v7.widget.CardView> 

Answer 1

Versuchen Höhe in Ihrem RecyclerViewandroid:layout_height="0dp"-android:layout_height="match_parent" Einstellung.

0dp Höhe wird in LinearLayout verwendet, Ihre ist RelativeLayout.