我使用了Androidhive的cardView和RecyclerView教程，但是cardview的XML并没有显示出来......
我的activity_main和content_main可见，但我的cardview不可见......
我该如何解决？
这是我的cardview xml：
<LinearLayout 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.support.v7.widget.CardView
android:id="@+id/card_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:layout_margin="@dimen/card_margin"
android:elevation="3dp"
card_view:cardCornerRadius="0dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/thumbnail"
android:layout_width="match_parent"
android:layout_height="160dp"
android:background="?attr/selectableItemBackgroundBorderless"
android:clickable="true"
android:scaleType="fitXY" />
<TextView
android:id="@+id/title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/thumbnail"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:paddingTop="10dp"
android:textColor="@color/cardview_dark_background"
android:textSize="15dp" />
<TextView
android:id="@+id/count"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/title"
android:paddingBottom="5dp"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:textSize="12dp" />
<ImageView
android:id="@+id/overflow"
android:layout_width="20dp"
android:layout_height="30dp"
android:layout_alignParentRight="true"
android:layout_below="@id/thumbnail"
android:layout_marginTop="10dp"
android:scaleType="centerCrop"
android:src="@mipmap/bandar_homa" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
这是我的content_main：
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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="ir.homa.HomaActivity"
tools:showIn="@layout/app_bar_homa">
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar"
android:layout_width="match_parent"
android:layout_height="@dimen/detail_backdrop_height"
android:fitsSystemWindows="true"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.CollapsingToolbarLayout
android:id="@+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:expandedTitleTextAppearance="@android:color/transparent"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/backdrop"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:scaleType="centerCrop"
app:layout_collapseMode="parallax"
android:layout_alignParentTop="true" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:gravity="center_horizontal"
android:orientation="vertical">
<TextView
android:id="@+id/love_music"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/backdrop_title"
android:textColor="@android:color/white"
android:textSize="@dimen/backdrop_title" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/backdrop_subtitle"
android:textColor="@android:color/white"
android:textSize="@dimen/backdrop_subtitle" />
</LinearLayout>
</RelativeLayout>
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<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"
android:background="@color/viewBg"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="ir.homa.HomaActivity"
tools:showIn="@layout/activity_homa">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:clipToPadding="false"
android:scrollbars="vertical" />
</RelativeLayout>
</android.support.design.widget.CoordinatorLayout>
这是我的activity_main：
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout 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:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="@layout/app_bar_homa"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_homa"
app:menu="@menu/activity_homa_drawer" />
</android.support.v4.widget.DrawerLayout>
更新：
MainActivity：
package ir.homa;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.Rect;
import android.os.Bundle;
import android.support.design.widget.AppBarLayout;
import android.support.design.widget.CollapsingToolbarLayout;
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.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.TypedValue;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import java.util.List;
public class HomaActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private RecyclerView recyclerView;
private HotelListAdapter adapter;
private List<HotelList> hotelList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_homa);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
initCollapsingToolbar();
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);
}
private void initCollapsingToolbar() {
final CollapsingToolbarLayout collapsingToolbar =
(CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
collapsingToolbar.setTitle(" ");
AppBarLayout appBarLayout = (AppBarLayout) findViewById(R.id.appbar);
appBarLayout.setExpanded(true);
// hiding & showing the title when toolbar expanded & collapsed
appBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
boolean isShow = false;
int scrollRange = -1;
@Override
public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
if (scrollRange == -1) {
scrollRange = appBarLayout.getTotalScrollRange();
}
if (scrollRange + verticalOffset == 0) {
collapsingToolbar.setTitle(getString(R.string.shoar));
isShow = true;
} else if (isShow) {
collapsingToolbar.setTitle(" ");
isShow = false;
}
}
});
}
private void prepareHotels() {
int[] covers = new int[]{
R.mipmap.bandar_homa,
R.mipmap.mashhad_homa,
R.mipmap.shiraz_homa,
};
HotelList a = new HotelList("هتل هما - بندر عباس", 13, covers[0]);
hotelList.add(a);
a = new HotelList("هتل هما - مشهد", 8, covers[1]);
hotelList.add(a);
a = new HotelList("هتل هما - شیراز", 11, covers[2]);
hotelList.add(a);
adapter.notifyDataSetChanged();
}
/**
* RecyclerView item decoration - give equal margin around grid item
*/
public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
private int spanCount;
private int spacing;
private boolean includeEdge;
public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
this.spanCount = spanCount;
this.spacing = spacing;
this.includeEdge = includeEdge;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
int position = parent.getChildAdapterPosition(view); // item position
int column = position % spanCount; // item column
if (includeEdge) {
outRect.left = spacing - column * spacing / spanCount; // spacing - column * ((1f / spanCount) * spacing)
outRect.right = (column + 1) * spacing / spanCount; // (column + 1) * ((1f / spanCount) * spacing)
if (position < spanCount) { // top edge
outRect.top = spacing;
}
outRect.bottom = spacing; // item bottom
} else {
outRect.left = column * spacing / spanCount; // column * ((1f / spanCount) * spacing)
outRect.right = spacing - (column + 1) * spacing / spanCount; // spacing - (column + 1) * ((1f / spanCount) * spacing)
if (position >= spanCount) {
outRect.top = spacing; // item top
}
}
}
}
/**
* Converting dp to pixel
*/
private int dpToPx(int dp) {
Resources r = getResources();
return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, r.getDisplayMetrics()));
}
@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.homa, 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) {
Intent intent = new Intent(HomaActivity.this, LoginActivity.class);
startActivity(intent);
finish();
} else if (id == R.id.nav_gallery) {
Intent intent = new Intent(HomaActivity.this, RegisterActivity.class);
startActivity(intent);
finish();
} 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;
}
}
HotelListAdapter：
package ir.homa;
import android.content.Context;
import android.support.v7.widget.PopupMenu;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import com.bumptech.glide.Glide;
import java.util.List;
/**
* Created by SMQ on 7/3/2016.
*/
public class HotelListAdapter extends RecyclerView.Adapter<HotelListAdapter.MyViewHolder> {
private Context mContext;
private List<HotelList> hotelList;
public class MyViewHolder extends RecyclerView.ViewHolder {
public TextView title, count;
public ImageView thumbnail, overflow;
public MyViewHolder(View view) {
super(view);
title = (TextView) view.findViewById(R.id.title);
count = (TextView) view.findViewById(R.id.count);
thumbnail = (ImageView) view.findViewById(R.id.thumbnail);
overflow = (ImageView) view.findViewById(R.id.overflow);
}
}
public HotelListAdapter(Context mContext, List<HotelList> hotelList) {
this.mContext = mContext;
this.hotelList = hotelList;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.hotel_list, parent, false);
return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(final MyViewHolder holder, int position) {
HotelList hotel = hotelList.get(position);
holder.title.setText(hotel.getName());
holder.count.setText(hotel.getNumOfRooms() + " اتاق");
// loading hotel cover using Glide library
Glide.with(mContext).load(hotel.getThumbnail()).into(holder.thumbnail);
holder.overflow.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
showPopupMenu(holder.overflow);
}
});
}
/**
* Showing popup menu when tapping on 3 dots
*/
private void showPopupMenu(View view) {
// inflate menu
PopupMenu popup = new PopupMenu(mContext, view);
MenuInflater inflater = popup.getMenuInflater();
inflater.inflate(R.menu.hotel_list_menu, popup.getMenu());
popup.setOnMenuItemClickListener(new MyMenuItemClickListener());
popup.show();
}
class MyMenuItemClickListener implements PopupMenu.OnMenuItemClickListener {
public MyMenuItemClickListener() {
}
@Override
public boolean onMenuItemClick(MenuItem menuItem) {
switch (menuItem.getItemId()) {
case R.id.action_add_favourite:
Toast.makeText(mContext, "افزودن به علاقه مندی ها", Toast.LENGTH_SHORT).show();
return true;
case R.id.action_hotel_next:
Toast.makeText(mContext, "هتل بعدی", Toast.LENGTH_SHORT).show();
return true;
default:
}
return false;
}
}
@Override
public int getItemCount() {
return hotelList.size();
}
}
HotelList：
package ir.homa;
/**
* Created by SMQ on 7/3/2016.
*/
public class HotelList {
private String name;
private int numOfRooms;
private int thumbnail;
public HotelList() {
}
public HotelList(String name, int numOfRooms, int thumbnail) {
this.name = name;
this.numOfRooms = numOfRooms;
this.thumbnail = thumbnail;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getNumOfRooms() {
return numOfRooms;
}
public void setNumOfRooms(int numOfRooms) {
this.numOfRooms = numOfRooms;
}
public int getThumbnail() {
return thumbnail;
}
public void setThumbnail(int thumbnail) {
this.thumbnail = thumbnail;
}
}
我为此设置了工具：上下文，但它还没有工作......
答案 0 :(得分：1)
它永远不会出现，bcz你忘记在mainActivity中添加一些行。
将此行放入onCreate：
prepareHotels();
adapter= new HotelListAdapter(getApplicationContext, hotelList);
recycleview.setAdapter(adapter);