ListView的运行效率与点击事件

提升ListView的运行效率

ListView的缓存原理

1、Adapter是ListView与数据之间的桥梁
2、ListView在开始绘制的时候，系统首先调用getCount（）方法，根据返回值得到ListView的长度，然后根据这个长度，调用getView（）一行一行地绘制ListView的每一项。
3、当ListView的每一项将要显示时，都会调用Adapter的getView（）方法返回一个View。
4、ListView中有多少项，就调用多少次getView（）方法去创建每一项的View，这一过程是耗时操作。

程序

public class MyListViewActivity extends AppCompatActivity  {private ListView mListView;    private List<Student> mData;     @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);   setContentView(R.layout.activity_my_list_view);   mListView= (ListView) findViewById(R.id.listview);       initData();        LayoutInflater inflater=getLayoutInflater();        Studentadapter adapter=new Studentadapter(inflater,mData);       mListView.setAdapter(adapter);       }    private void initData() {        mData=new ArrayList<>();        Student zhangsan=new Student("张三","20","男","吃",R.mipmap.uqiwei);        Student lisi=new Student("李四","22","女","睡觉",R.mipmap.yangmi);        Student wangwu=new Student("王五","25","男","打游戏",R.mipmap.ic_launcher);        Student zhaoliu=new Student("赵六","23","女","逛街",R.mipmap.uqiwei);        for(int i=0;i<50;i++) {            mData.add(zhangsan);            mData.add(lisi);            mData.add(wangwu);            mData.add(zhaoliu);        }    }"****************************************************"public class Studentadapter extends BaseAdapter {    private List<Student> mData;    private LayoutInflater mInflater;    public Studentadapter(LayoutInflater inflater, List<Student> data) {        mInflater = inflater;        mData = data;    }    @Override    public int getCount() {        //得到ListView要显示数据的条数        return mData.size();    }    @Override    public Object getItem(int position) {        //返回索引        return position;    }    @Override    public long getItemId(int position) {        //返回索引        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        //LayoutInflater        Student student = mData.get(position);        ViewHolder viewHolder = null;        if (convertView == null) {            viewHolder = new ViewHolder();            convertView = mInflater.inflate(R.layout.simple_adapter, null);            viewHolder.imageView = (ImageView) convertView.findViewById(R.id.imageview_photo);            viewHolder.textView_name = (TextView) convertView.findViewById(R.id.textview_name);            viewHolder.textView_age = (TextView) convertView.findViewById(R.id.textview_age);            viewHolder.textView_sex = (TextView) convertView.findViewById(R.id.textview_sex);            viewHolder.textView_hobby = (TextView) convertView.findViewById(R.id.textview_hobby);            convertView.setTag(viewHolder);        } else {            viewHolder = (ViewHolder) convertView.getTag();        }        viewHolder.textView_name.setText(student.getName());        viewHolder.textView_age.setText(student.getAge());        viewHolder.textView_hobby.setText(student.getHobby());        viewHolder.textView_sex.setText(student.getSex());        viewHolder.imageView.setImageResource(student.getImg());        return convertView;    }    class ViewHolder {        TextView textView_name;        TextView textView_age;        TextView textView_sex;        TextView textView_hobby;        ImageView imageView;    }}"*******************************************"<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent" android:layout_height="match_parent">    <ImageView        android:id="@+id/imageview_photo"        android:layout_width="100dp"        android:layout_height="100dp"        android:src="@mipmap/yangmi"        /><LinearLayout    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:orientation="horizontal"    android:layout_margin="20dp">    <TextView        android:id="@+id/textview_name"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="姓名"/>    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="vertical"        android:layout_marginLeft="20dp"        android:layout_marginRight="20dp"       >        <TextView            android:id="@+id/textview_age"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="年龄"/>        <TextView            android:id="@+id/textview_sex"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="性别"/>    </LinearLayout>    <TextView        android:id="@+id/textview_hobby"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="爱好"/></LinearLayout></LinearLayout>"********************************************************"public class Student {    private String name;    private String hobby;    private String  age;    private String  sex;    private int img;    public Student(String name,String age,String sex,String hobby,int img){        this.name=name;        this.age=age;        this.sex=sex;        this.hobby=hobby;        this.img=img;    }    public int getImg() {      return img;    }    public void setImg(int img) {        this.img = img;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public void setHobby(String hobby) {        this.hobby = hobby;    }    public void setAge(String age) {        this.age = age;    }    public void setSex(String sex) {        this.sex = sex;    }    public String getSex() {        return sex;    }    public String getHobby() {        return hobby;    }    public String getAge() {        return age;    }}

结果图：

ListView水果界面及各种效果图

ListView界面

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent" android:layout_height="match_parent">    <ListView        android:id="@+id/listview_fruit"        android:layout_width="match_parent"        android:layout_height="wrap_content">    </ListView></LinearLayout>

MyFruitActivity

public class MyFruitActivity extends AppCompatActivity {private ListView mListView;    private List<Fruit> mFruits;    private Fruitadapter adapter;    private  LayoutInflater Inflater;    private  View mHeaderView;    private Button mBtnCheckedAll;    private  View mFooterView;    private Button mBtnCheckedOver;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.layout_fruit);        mListView= (ListView) findViewById(R.id.listview_fruit);        Inflater=getLayoutInflater();        initData();        mFooterView=Inflater.inflate(R.layout.fruit_footer, null);        mHeaderView=Inflater.inflate(R.layout.fruit_header,null);        mBtnCheckedOver= (Button) mFooterView.findViewById(R.id.button_overChecked);        mBtnCheckedAll= (Button) mHeaderView.findViewById(R.id.button_allChecked);        mBtnCheckedOver.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                adapter.checkedOver();            }        });       mBtnCheckedAll.setOnClickListener(new View.OnClickListener() {           @Override           public void onClick(View v) {               //此处要全选               adapter.checkedAll();           }       });        mListView.addHeaderView(mHeaderView);       mListView.addFooterView(mFooterView);        adapter=new Fruitadapter(Inflater,mFruits);        mListView.setAdapter(adapter);        mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {            @Override            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {                Log.d("myfruit","点击的水果是："+mFruits.get(position-1).getName());                adapter.itemSelect(position-1);            }        });    }    private void initData() {  mFruits=new ArrayList<>();        for(int i=0;i<50;i++) {            Fruit apple=new Fruit("苹果",R.mipmap.pineapple);            Fruit banana=new Fruit("香蕉",R.mipmap.fbanana);            Fruit strawberry=new Fruit("葡萄",R.mipmap.fstrawberry);            mFruits.add(apple);            mFruits.add(banana);            mFruits.add(strawberry);        }    }

全选和反选XML文件

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent" android:layout_height="match_parent"><Button    android:id="@+id/button_allChecked"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="全选"/></LinearLayout>"********************************************************"<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent" android:layout_height="match_parent"><Button    android:id="@+id/button_overChecked"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="反选"/></LinearLayout>

水果布局XML文件

<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:gravity="center"    android:orientation="horizontal"    tools:context="com.example.administrator.mywiget.MyFruitActivity"> <CheckBox        android:id="@+id/checkbox_choose"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:focusable="false"        android:text="选择水果"/>    <ImageView        android:id="@+id/imageview_fruit"        android:layout_width="100dp"        android:layout_height="100dp"        android:src="@mipmap/peach"/>    <TextView        android:id="@+id/textview_name"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="苹果"        /></LinearLayout>

布局视图：

Fruit类

public class Fruit {    private String name;    private int Img;    private boolean isChecked;    public boolean isChecked() {        return isChecked;    }    public void setIsChecked(boolean isChecked) {        this.isChecked = isChecked;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getImg() {        return Img;    }    public void setImg(int img) {        Img = img;    }    public Fruit(String name, int img) {        this.name = name;        Img = img;    }}

Fruitadapter适配器

public class Fruitadapter extends BaseAdapter {    private List<Fruit> mFruits;    private LayoutInflater mInflater;    private boolean[] mManagerAllCheckBox;    public Fruitadapter(LayoutInflater Inflater, List<Fruit> Fruits) {        mInflater = Inflater;        mFruits = Fruits;        //有多少条数据就有多少个checkBox        mManagerAllCheckBox = new boolean[Fruits.size()];    }    /**     * 全部选择     */    public void checkedAll(){        for(int i=0;i<mManagerAllCheckBox.length;i++){            mManagerAllCheckBox[i]=true;        }        notifyDataSetChanged();    }    public void checkedOver(){        for (int i=0;i<mManagerAllCheckBox.length;i++){            mManagerAllCheckBox[i]=!mManagerAllCheckBox[i];        }        notifyDataSetChanged();    }    public void itemSelect(int position) {        mManagerAllCheckBox[position] = !mManagerAllCheckBox[position];        notifyDataSetChanged();    }    @Override    public int getCount() {        return mFruits.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) {        ViewHolder viewHolder = null;        if (convertView == null) {            convertView = mInflater.inflate(R.layout.activity_my_fruit, null);            viewHolder = new ViewHolder();            viewHolder.checkBox = (CheckBox) convertView.findViewById(R.id.checkbox_choose);            viewHolder.imageView = (ImageView) convertView.findViewById(R.id.imageview_fruit);            viewHolder.textView = (TextView) convertView.findViewById(R.id.textview_name);            convertView.setTag(viewHolder);        } else {            viewHolder = (ViewHolder) convertView.getTag();        }        Fruit fruit = mFruits.get(position);        viewHolder.imageView.setImageResource(fruit.getImg());        viewHolder.textView.setText(fruit.getName());        viewHolder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {            @Override            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {                Log.d("myFruit", "选择框发生的变化：" + isChecked);                mManagerAllCheckBox[position] = isChecked;                notifyDataSetChanged();            }        });        viewHolder.checkBox.setChecked(mManagerAllCheckBox[position]);        return convertView;    }    class ViewHolder {        CheckBox checkBox;        ImageView imageView;        TextView textView;    }}

结果图