自定义adapter 及其性能优化

基本属性和常见问题

先来看看一些基本属性和常见问题。
listview 常用属性
cachecolorhint：缓存默认颜色一般给全透明
android:cacheColorHint=”#00ffffff”
divder:分隔线
android:divider=”#000000”
android:dividerHeight=”1dp”
改变按下的颜色：
item的背景改为drawable中的pressed.xml
加头部和底部：
默认position会加一
必须在setadapter之前加载

checkbox问题
。。。因为是同一个对象
adapter中有一个及时刷新的方法,在不滑动的情况下就可以刷新界面
notifyDataSetchange
一般在设置点击事件之后，都要使用该方法

点击事件问题：点击listview没有反应。只有点击checkbox才有反应
事件传递
屏幕 activity viewGroup
checkbox button
因为focusable默认为true
设为false则可以点击以外的区域

自定义的基本步骤

一，新建listview布局文件:listview只相当于书架

<RelativeLayout 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"
    tools:context="com.lingzhuo.test4.FriutActivity">

    <ListView
        android:id="@+id/mListViewFruit"
        android:cacheColorHint="#00ffffff"
        android:divider="#000000"
        android:dividerHeight="1dp"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        >
    ListView>

RelativeLayout>

二，自定义item布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:gravity="center_vertical"
    >

    <CheckBox
        android:id="@+id/mCheckBoxFruit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:focusable="false"
        android:text="选择水果"
        />

    <ImageView
        android:id="@+id/mImageViewFruit"
        android:layout_width="70dp"
        android:layout_height="70dp"
        />

    <TextView
        android:id="@+id/mTextViewFruit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="水果的名字"
        />

LinearLayout>

定义model类来描述item的属性

package com.lingzhuo.test4.modle;

/**
 * Created by heinika on 2015/8/25.
 */
public class Fruit {
    private String name;
    private int image;
    private boolean isChecked;

    public boolean changeChecked(){
        isChecked = !isChecked;
        return isChecked;
    }

    public boolean getIsChecked() {
        return isChecked;
    }

    public void setIsChecked(boolean isChecked) {
        this.isChecked = isChecked;
    }

    public Fruit(String name, int image) {
        this.name = name;
        this.image = image;
    }

    public String getName() {
        return name;
    }

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

    public int getImage() {
        return image;
    }

    public void setImage(int image) {
        this.image = image;
    }
}

定义适配器实现baseadapter接口

package com.lingzhuo.test4.adapter;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.ImageView;
import android.widget.TextView;

import com.lingzhuo.test4.R;
import com.lingzhuo.test4.modle.Fruit;

import java.util.List;

/**
 * Created by heinika on 2015/8/25.
 */
public class FruitAdapter extends BaseAdapter{
    private List fruits;
    private LayoutInflater inflater;
    private boolean isChecked;

    public FruitAdapter(LayoutInflater inflater,List data){
        this.inflater = inflater;
        fruits = data;
    }
    @Override
    public int getCount() {
        return fruits.size();
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        Fruit fruit = fruits.get(position);
        FruitHold fruitHold=null;
        if(convertView==null){
            fruitHold = new FruitHold();
            convertView = inflater.inflate(R.layout.item_fruit_adapter,null);
            fruitHold.mCheckBoxFruit = (CheckBox) convertView.findViewById(R.id.mCheckBoxFruit);
            fruitHold.mImageViewFruit = (ImageView) convertView.findViewById(R.id.mImageViewFruit);
            fruitHold.mTextViewFruit = (TextView) convertView.findViewById(R.id.mTextViewFruit);
            convertView.setTag(fruitHold);
        }else{
            fruitHold = (FruitHold) convertView.getTag();
        }
        fruitHold.mImageViewFruit.setImageResource(fruit.getImage());
        fruitHold.mTextViewFruit.setText(fruit.getName());
        fruitHold.mCheckBoxFruit.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            //局部变量只有转变为常量才能传入匿名内部类
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                fruits.get(position).setIsChecked(isChecked);
            }
        });
        fruitHold.mCheckBoxFruit.setChecked(fruit.getIsChecked());
        return convertView;
    }

//    public void changeCheck(int position){
//        fruits.get(position).setIsChecked(!fruits.get(position).getIsChecked());
//        notifyDataSetChanged();                     //刷新数据
//    }

    public void allSelect(){
        for(int i=0;itrue);
        }
        notifyDataSetChanged();
    }

    public void allRevrse(){
        for(int i=0;i

在主类中找到listview并setadapter并监听事件

package com.lingzhuo.test4;

import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListView;

import com.lingzhuo.test4.adapter.FruitAdapter;
import com.lingzhuo.test4.modle.Fruit;

import java.util.ArrayList;

public class FriutActivity extends Activity {
    private ArrayList fruits;
    private LayoutInflater inflater;
    private ListView mListViewFruit;
    private FruitAdapter fruitAdapter;
    private View mHeaderView;
    private Button mBtnAllSelect;
    private Button mBtnAllRevrse;
    private View mFootView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_friut);
        mListViewFruit = (ListView) findViewById(R.id.mListViewFruit);
        inflater = getLayoutInflater();   //只有activity才有getLayoutInflater()方法
        fruits = initFruits();
        fruitAdapter = new FruitAdapter(inflater,fruits);

        mHeaderView = inflater.inflate(R.layout.all_select_button,null);
        mListViewFruit.addHeaderView(mHeaderView);                          //会导致position加一
        mBtnAllSelect = (Button) mHeaderView.findViewById(R.id.mBtnAllSelect);
        mBtnAllSelect.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                fruitAdapter.allSelect();
            }
        });
        mFootView = inflater.inflate(R.layout.all_revrse_button,null);
        mListViewFruit.addFooterView(mFootView);
        mBtnAllRevrse = (Button) mFootView.findViewById(R.id.mBtnAllRevrse);
        mBtnAllRevrse.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                fruitAdapter.allRevrse();
            }
        });

        mListViewFruit.setAdapter(fruitAdapter);

        mListViewFruit.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView parent, View view, int position, long id) {
                fruits.get(position-1).setIsChecked(fruits.get(position-1).changeChecked());    //当点击item
                fruitAdapter.notifyDataSetChanged();                     //刷新数据
            }
        });
    }

    private ArrayList initFruits() {
        fruits = new ArrayList();
        for(int i =0;i<10;i++) {
            fruits.add(new Fruit("apple", R.mipmap.apple));
            fruits.add(new Fruit("pineapple", R.mipmap.pineapple));
            fruits.add(new Fruit("strawberry", R.mipmap.strawberry));
            fruits.add(new Fruit("watermelon", R.mipmap.watermelon));
            fruits.add(new Fruit("apple", R.mipmap.apple));
        }
        return fruits;
    }

}

性能优化的具体分析

package com.lingzhuo.test4.adapter;

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.lingzhuo.test4.R;
import com.lingzhuo.test4.modle.Student;

import java.util.List;

/**
 * Created by Heinika on 2015/8/24.
 */
public class StudentAdapter extends BaseAdapter{
    private List mData;
    private LayoutInflater mInflater;
    //将inflater和数据传到适配器中
    public StudentAdapter(LayoutInflater inflater,List data){
        this.mInflater = inflater;
        this.mData = data;
    }

    @Override
    public int getCount() {
        return mData.size();
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Student student = mData.get(position);
        ViewHold viewHold=null;
        if(convertView==null){                                                            //只有充满的的时候才不为空
            viewHold = new ViewHold();
            convertView = mInflater.inflate(R.layout.item_simple_adapter,null);      //避免每次重复加载
            viewHold.mImageViewPhoto = (ImageView) convertView.findViewById(R.id.mImageViewPhoto);  //findviewbyid为耗时操作
            viewHold.textView_name = (TextView) convertView.findViewById(R.id.tv_name);              //只当convertView为空时才需要findviewbyid
            viewHold.textView_age = (TextView) convertView.findViewById(R.id.tv_age);
            viewHold.textView_sex = (TextView) convertView.findViewById(R.id.tv_sex);
            convertView.setTag(viewHold);                                                  //将viewHold存到convertView
        }else{                                                                          //convertView不为空的加载，convertView创建到一定个数就不再创建
            viewHold = (ViewHold) convertView.getTag();
        }
        viewHold.mImageViewPhoto.setImageResource(student.getImgId());
        viewHold.textView_name.setText(student.getName());
        viewHold.textView_age.setText(student.getAge()+"");
        viewHold.textView_sex.setText(student.getSex());
        return convertView;
    }

    class ViewHold{
        ImageView mImageViewPhoto;
        TextView textView_name;
        TextView textView_age;
        TextView textView_sex;
    }
}