ListView（优化），自定义Layout和adapter，entity，ViewHolder，ConvertView用法案例（phone）

自定义实体类：PhoneEntity.java

package com.example.entity;

/**
* Created by Administrator on 2017/2/16.
*/

public class PhoneEntity {
private int img;
private String name,price,countNum;

public int getImg() {
return img;
}

public String getName() {
return name;
}

public String getPrice() {
return price;
}

public String getCountNum() {
return countNum;
}

public void setImg(int img) {
this.img = img;
}

public void setName(String name) {
this.name = name;
}

public void setPrice(String price) {
this.price = price;
}

public void setCountNum(String countNum) {
this.countNum = countNum;
}
}

自定义布局（Layout） acvitity_phone_list.xml

<?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"
android:layout_margin="5dp">
<ImageView
android:src="@drawable/ihone7plus"
android:id="@+id/img_phone"
android:layout_width="150dp"
android:layout_height="150dp"
android:layout_margin="10dp"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/phone_name"
android
f51a
:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ihone7Plus玫瑰金"
android:textSize="20dp"
android:layout_marginTop="50sp"/>
<TextView
android:id="@+id/phone_price"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="￥7188"
android:textSize="20dp"
android:textColor="#f45959" />
<TextView
android:id="@+id/phone_counter"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="50353条评价"
android:textSize="15dp"
android:textColor="@android:color/darker_gray"/>

</LinearLayout>

</LinearLayout>

自定义acvitity_phone.xml(定义ListView)

<?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_phone"
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.jump.PhoneActivity">
<ListView
android:id="@+id/lv_phone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"></ListView>

</RelativeLayout>

自定义PhoneAcvitity

package com.example.jump;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;

import com.example.adapter.PhoneAdapter;
import com.example.entity.PhoneEntity;

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

public class PhoneActivity extends AppCompatActivity {
private ListView lv;
private int[] ids=new int[]{R.drawable.ihone7plus,R.drawable.mi5s,R.drawable.leshi2,R.drawable.rongyao8};
private String[] phonenames=new String[]{"苹果7Plus,128G玫瑰金","小米5S全网通版，32G亚光金","乐视2原力金32GB内存","荣耀8全网通4GB32G珠光白"};
private String[] phoneprice=new String[]{"￥7188","￥1899","￥1099","￥2229"};
private String[] phonecounter=new String[]{"50353条评价","20353条评价","34553条评价","65053条评价"};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_phone);
lv= (ListView) findViewById(R.id.lv_phone);
intiCustomPhoneAdapter();
}
private void intiCustomPhoneAdapter(){
List<PhoneEntity> list =new ArrayList<PhoneEntity>();
for (int i = 0; i < phonenames.length; i++) {
PhoneEntity phone=new PhoneEntity();
phone.setImg(ids[i]);
phone.setName(phonenames[i]);
phone.setPrice(phoneprice[i]);
phone.setCountNum(phonecounter[i]);
list.add(phone);
}
PhoneAdapter phoneada=new PhoneAdapter(list,this);
lv.setAdapter(phoneada);
}
}

自定义adapter（PhoneAdapter）
复用convertview,减少item的数量：节省内存，运行更流畅
使用ViewHolder类，减少findviewbyid的次数，好处就是运行更流畅

package com.example.adapter;

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

import com.example.entity.PhoneEntity;
import com.example.jump.R;

import java.util.List;

/**
* Created by Administrator on 2017/2/16.
*/

public class PhoneAdapter extends BaseAdapter {
private List<PhoneEntity> list;//数据源
private Context context;//上下文对象
private LayoutInflater inflater;

public PhoneAdapter(List<PhoneEntity> list, Context context) {
this.list = list;
this.context = context;
inflater=LayoutInflater.from(context);
}
//有参的构造函数，为数据源，上下文对象复制，同时实例化布局加载器
//有多少条数据，需要创建多少个item布局
@Override
public int getCount() {
return list.size();
}
//返回position对应位置的数据
@Override
public Object getItem(int position) {
return list.get(position);
}
//返回position对应位置item的id
@Override
public long getItemId(int position) {
return position;
}

/**
* 具体定义加载item布局，并将数据显示到item布局上的方法。
* @param position
* @param convertView
* @param parent
* @return
*/
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder=null;
//加载item布局 将xml布局加载到内存中，形成一个view
if(convertView==null){ //被复用后的convertview类依然包含tag
holder=new ViewHolder();
convertView=inflater.inflate(R.layout.activity_phone_list,null);
holder.iv= (ImageView) convertView.findViewById(R.id.img_phone);
holder.tv_phonename= (TextView) convertView.findViewById(R.id.phone_name);
holder.tv_phoneprice= (TextView) convertView.findViewById(R.id.phone_price);
holder.tv_phonecounter= (TextView) convertView.findViewById(R.id.phone_counter);
convertView.setTag(holder);
}else {//convertview不为空，不为空则说明convertview包含tag
holder= (ViewHolder) convertView.getTag();
}
//        View view=inflater.inflate(R.layout.activity_phone_list,null);
//实例化item布局上的控件
//          ImageView iv= (ImageView) view.findViewById(R.id.img_phone);
//          TextView tv_phonename= (TextView) view.findViewById(R.id.phone_name);
//          TextView tv_phoneprice= (TextView) view.findViewById(R.id.phone_price);
//          TextView tv_phonecounter= (TextView) view.findViewById(R.id.phone_counter);
//往控件上显示数据
//获取position对应位置的数据
PhoneEntity phonety= (PhoneEntity) getItem(position);
holder.iv.setImageResource(phonety.getImg());
holder.tv_phonename.setText(phonety.getName());
holder.tv_phoneprice.setText(phonety.getPrice());
holder.tv_phonecounter.setText(phonety.getCountNum());
return convertView;
}
class ViewHolder{
public ImageView iv;
public  TextView tv_phonename;
public  TextView tv_phoneprice;
public TextView tv_phonecounter;
}
}

MainAcvitity

package com.example.jump;

import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;

import com.example.adapter.MyAdapter;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button textButton, tv_btn, btn_edit, btn_cb, btn_imgsca, work_activity, rg_btn, timedatepick_btn, arrayadapter, btn_myadapter, btn_phone;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}

private void initView() {

tv_btn = (Button) findViewById(R.id.btn_test);
tv_btn.setOnClickListener(this);
btn_edit = (Button) findViewById(R.id.btn_edit);
btn_edit.setOnClickListener(this);
btn_cb = (Button) findViewById(R.id.btn_cb);
btn_cb.setOnClickListener(this);
btn_imgsca = (Button) findViewById(R.id.btn_imgsca);
btn_imgsca.setOnClickListener(this);
work_activity = (Button) findViewById(R.id.work_activity);
work_activity.setOnClickListener(this);
rg_btn = (Button) findViewById(R.id.rg_btn);
rg_btn.setOnClickListener(this);
timedatepick_btn = (Button) findViewById(R.id.datetimepick_btn);
timedatepick_btn.setOnClickListener(this);
arrayadapter = (Button) findViewById(R.id.lv_arrayadapter);
arrayadapter.setOnClickListener(this);
btn_myadapter = (Button) findViewById(R.id.btn_myadapter);
btn_myadapter.setOnClickListener(this);
btn_phone = (Button) findViewById(R.id.btn_phone);
btn_phone.setOnClickListener(this);

}

@Override
public void onClick(View v) {
switch (v.getId()) {

case R.id.btn_edit:
startNewApplication(EditTestActivity.class);
break;
case R.id.btn_cb:
startNewApplication(CheckBoxActivity.class);
case R.id.btn_imgsca:
startNewApplication(ImageScaleActivity.class);
case R.id.work_activity:
startNewApplication(WorkActivity.class);
break;
case R.id.rg_btn:
startNewApplication(RadioGroupActivity.class);
break;
case R.id.datetimepick_btn:
startNewApplication(TimeDatePickerActivity.class);
break;
case R.id.btn_myadapter:
startNewApplication(ArrayAdapterActivity.class);
break;
case R.id.btn_phone:
startNewApplication(PhoneActivity.class);
break;
}

}

private void startNewApplication(Class<?> cls) {
Intent intent = new Intent(this, cls);
startActivity(intent);
}
}