前言

基于RecyclerView的图片浏览器

一、作业要求

使用RecyclerView实现一个图片列表，如图1所示，当点击其中的任一个图片时，会在一个新的Activity中显示被点击的图片，如图2所示。

# 二、具体实现

## 1.布局代码 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="乔博春的homework展示"
        android:textSize="20sp"
        android:textColor="@color/white"
        />
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

recyclerview_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="10dp"
    tools:ignore="UseCompoundDrawables">

    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:transitionName="sharedView"
        tools:ignore="ContentDescription" />

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:textSize="20sp"
        android:textColor="@color/black"        />
</LinearLayout>

activity_newitem.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical">
    <!--注意这里的sharedView-->
    <ImageView
        android:id="@+id/image1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@mipmap/ic_launcher"
        android:transitionName="sharedView"
        tools:ignore="ContentDescription" />
</LinearLayout>

二、程序代码

newitem.java

package com.example.homework_forth;
import android.os.Bundle;
import android.widget.ImageView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
public class newitem extends AppCompatActivity {
    private ImageView image1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_newitem);
        image1 = findViewById(R.id.image1);
        image1.setOnClickListener(view -> ActivityCompat.finishAfterTransition(newitem.this));
    }
}

MainActivity.kt

package com.example.homework_forth
import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
class MainActivity : AppCompatActivity() {
    private val coreList = ArrayList<core>()
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        initCore()
        val recyclerView = findViewById<View>(R.id.recycler_view) as RecyclerView
        val layoutManager = GridLayoutManager(this,3)
        recyclerView.layoutManager = layoutManager
        val adapter = coreAdapter(coreList)
        recyclerView.adapter = adapter
    }
    private fun initCore() {
        for (i in 0..1) {
            val Aiden = core("Aiden", R.drawable.p1pic)
            coreList.add(Aiden)
            val Mia = core("Mia", R.drawable.p2pic)
            coreList.add(Mia)
            val Jackson = core("Jackson", R.drawable.p3pic)
            coreList.add(Jackson)
            val Jacob = core("Jacob", R.drawable.p4pic)
            coreList.add(Jacob)
            val Emily = core("Emily", R.drawable.p5pic)
            coreList.add(Emily)
            val Emma = core("Emma", R.drawable.p6pic)
            coreList.add(Emma)
            val lucky = core("lucky", R.drawable.p7pic)
            coreList.add(lucky)
            val Noah = core("Noah", R.drawable.p8pic)
            coreList.add(Noah)
            val Lucas = core("Lucas", R.drawable.p9pic)
            coreList.add(Lucas)
            val Caden = core("Caden", R.drawable.p0pic)
            coreList.add(Caden)
        }
    }

}

core.kt

package com.example.homework_forth
class core( val name : String, val imageId : Int)

coreAdapter.java

package com.example.homework_forth;
import android.app.Activity;
import android.app.ActivityOptions;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
public class coreAdapter extends RecyclerView.Adapter<coreAdapter.ViewHolder> {
    private final List<core> mcoreList;
    public  coreAdapter (List <core> coreList){
        mcoreList = coreList;
    }
    static class ViewHolder extends RecyclerView.ViewHolder{
        View coreView;
        ImageView Image;
        TextView Name;

        public ViewHolder (View view)
        {
            super(view);
            coreView = view;
            Image = (ImageView) view.findViewById(R.id.image);
            Name = (TextView) view.findViewById(R.id.name);
        }
    }
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType){
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_item,parent,false);
        final ViewHolder holder = new ViewHolder(view);

        holder.coreView.setOnClickListener(view1 -> view1.getContext().startActivity(
                new Intent(view1.getContext(),newitem.class),
                ActivityOptions.makeSceneTransitionAnimation((Activity) view1.getContext(), view1,"image").toBundle()
        ));
        return holder;
    }
    @Override
    public void onBindViewHolder(ViewHolder holder, int position){

        core Core = mcoreList.get(position);
        holder.Image.setImageResource(Core.getImageId());
        holder.Name.setText(Core.getName());
    }
    @Override
    public int getItemCount(){
        return mcoreList.size();
    }
}