java - 持有 RecyclerView 的片段未显示在 MainActivity 中
问题描述
我试图在我的主要活动中以片段的形式显示 RecyclerView。我没有收到任何错误,但片段仍然是空的,我找不到这个问题的解决方案。我只是有一个片段,其中有一个recyclerview,我在HomeFragment.java 中配置recyclerview,然后在MainParkActivity 中,我有一个FrameLayout,它被HomeFragment 替换。
MainParkActivity
package com.example.ipark;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;;
public class MainParkActivity extends AppCompatActivity {
private static final String TAG = "MainParkActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(TAG, "onCreate: started.");
Toolbar toolbar = findViewById(R.id.toolbar);
Fragment homeFragment = new HomeFragment();
setSupportActionBar(toolbar);
getSupportActionBar().setTitle("iParc");
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, homeFragment).commit();
}
}
首页片段
package com.example.ipark;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
public class HomeFragment extends Fragment {
private static final String TAG = "HomeFragment";
private ArrayList<String> mNames = new ArrayList<>();
private ArrayList<String> mImageUrls = new ArrayList<>();
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_home, container, false);
return rootView;
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
RecyclerView recyclerView = view.findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
giveInformation();
RecyclerViewAdapter adapter = new RecyclerViewAdapter(getContext(), mNames, mImageUrls);
recyclerView.setAdapter(adapter);
}
private void giveInformation() {
mImageUrls.add("https://loremflickr.com/300/300/bmw");
mNames.add("BMW");
mImageUrls.add("https://loremflickr.com/300/300/bmw");
mNames.add("Audi");
mImageUrls.add("https://loremflickr.com/300/300/bmw");
mNames.add("Hyundai");
mImageUrls.add("https://loremflickr.com/300/300/bmw");
mNames.add("Mercedes");
mImageUrls.add("https://loremflickr.com/300/300/bmw");
mNames.add("BMW");
mImageUrls.add("https://loremflickr.com/300/300/bmw");
mNames.add("Audi");
mImageUrls.add("https://loremflickr.com/300/300/bmw");
mNames.add("Hyundai");
mImageUrls.add("https://loremflickr.com/300/300/bmw");
mNames.add("Mercedes");
}
}
回收器视图适配器
package com.example.ipark;
import android.content.Context;
import android.support.annotation.NonNull;
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.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;
import com.bumptech.glide.Glide;
import java.util.ArrayList;
import de.hdodenhof.circleimageview.CircleImageView;
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder>{
private static final String TAG = "RecyclerViewAdapter";
private ArrayList<String> mImageNames;
private ArrayList<String> mImages;
private Context mContext;
public RecyclerViewAdapter(Context mContext, ArrayList<String> mImageNames, ArrayList<String> mImages) {
this.mImageNames = mImageNames;
this.mImages = mImages;
this.mContext = mContext;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_listitem, parent, false);
ViewHolder holder;
holder = new ViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, final int position) {
Log.d(TAG, "onBindViewHolder: called.");
Glide.with(mContext)
.asBitmap()
.load(mImages.get(position))
.into(holder.image);
holder.imageName.setText(mImageNames.get(position));
holder.parentLayout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d(TAG, "onClick: clicked on: " + mImageNames.get(position));
Toast.makeText(mContext, mImageNames.get(position), Toast.LENGTH_SHORT).show();
}
});
}
@Override
public int getItemCount() {
return mImageNames.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
CircleImageView image;
TextView imageName;
RelativeLayout parentLayout;
public ViewHolder(@NonNull View itemView) {
super(itemView);
image = itemView.findViewById(R.id.image);
imageName = itemView.findViewById(R.id.image_name);
parentLayout = itemView.findViewById(R.id.parent_layout);
}
}
}
}
activity_main 的 XML
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
tools:context=".MainParkActivity"
android:clipToPadding="false">
<include
android:id="@+id/toolbar"
layout="@layout/toolbar" />
<FrameLayout
android:id="@+id/fragment_container"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/toolbar">
</FrameLayout>
</android.support.constraint.ConstraintLayout>
fragment_home 的 XML
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toTopOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
解决方案
在您的fragment_home.xml中,您的Recyclerview
haslayout_height
和layout_width
0dp。将其更改为match_parent
. 您的代码中的其他所有内容都是正确的。我会评论它,但我目前没有评论权限!觉得有用就采纳吧!
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