复杂控件

package com.example.listview2;

/**
* Created by 刘鹏达 on 2017/9/12.
*/
//创建子项的实例,对应也要创建这个子项的布局，之后创建适配器放这些子项
public class Fruit {
private String name;
private int imageId;
public Fruit(String name,int imageId){
this.name=name;
this.imageId=imageId;
}

public String getName() {
return name;
}

public int getImageId() {
return imageId;
}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/fruit_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/fruit_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginLeft="10dp"/>
</LinearLayout>

package com.example.listview2;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;

/**
* Created by 刘鹏达 on 2017/9/12.
*/

public class FruitAdapter extends ArrayAdapter<Fruit> {
private int resourceId;
//适配器的构造方法的三个参数是上下文内容（也就是放入数据的activity），第二个为子项布局，第三个是数据集合
public FruitAdapter(Context context, int textViewResourceId,
List<Fruit> objects){
super(context,textViewResourceId,objects);
resourceId=textViewResourceId;
}

//该方法是给每一个子项设置数据

public View getView(int position, View convertView, ViewGroup parent){
Fruit fruit=getItem(position);//获取当前项的Fruit实例
View view;
ViewHolder viewHolder;
//如果view为空，那么加载布局和初始化子项的组件
if(convertView==null){
view=LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
viewHolder=new ViewHolder();
viewHolder.fruitImage=(ImageView)view.findViewById(R.id.fruit_image);
viewHolder.fruitName=(TextView)view.findViewById(R.id.fruit_name);
view.setTag(viewHolder);
}else { //不为空的时候，得到该布局的view，和获取到viewHolder
view=convertView;
viewHolder=(ViewHolder)view.getTag();//重新获取ViewHolder
}
viewHolder.fruitImage.setImageResource(fruit.getImageId());
viewHolder.fruitName.setText(fruit.getName());
return view;
}


class ViewHolder{
ImageView fruitImage;
TextView fruitName;
}
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.listview2.MainActivity">
<ListView
android:id="@+id/listview"
android:layout_width="match_parent"
android:layout_height="match_parent"></ListView>
</RelativeLayout>

package com.example.listview2;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;

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

 


/*
总结：
1.首先创建子项对象和子项布局
2.之后创建一个适配器，getView方法里面进行加载布局和控件（这边是改善效率的地方）
3.在Activity中建立数据集合，然后创建适配器，将数据集合传入，并且建立监听器进行监听

listview简单版：
直接利用ArrayAdapter<String> adapter=new ArrayAdapter<String>(Activity,布局。数据）
*/
public class MainActivity extends AppCompatActivity {
List<Fruit> fruitList=new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initFruits();
final FruitAdapter adapter=new FruitAdapter(MainActivity.this,R.layout.fruit_item,fruitList);
ListView listView=(ListView)findViewById(R.id.listview);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Fruit fruit=fruitList.get(position);
if(fruit.getName()=="apple"){
Toast.makeText(MainActivity.this,fruit.getName(),Toast.LENGTH_SHORT).show();;

}
}
});
}
private void initFruits(){
for(int i=0;i<2;i++){
Fruit apple=new Fruit("apple",R.mipmap.ic_launcher);
fruitList.add(apple);
}
}
}