自定义adapter的基础上Listview优化方案以及几个小错误（checkbox吃掉点击事件以及对象重复问题）

修改的是自定义adapter中的getview方法

@Override
public View getView(int position, View convertView, ViewGroup parent) {

Student student=mData.get(position);

if(convertView==null){
        convertView=minflater.inflate(R.layout.simple_adpter,null);//没有就创建
    }
//convertview代替了view，判断是否有划出屏幕的listview（convertview），如果没有就新创建，有就不用创建直接赋值
    ImageView imageview= (ImageView) convertView.findViewById(R.id.image_photo);
    TextView textview_name= (TextView) convertView.findViewById(R.id.text_name);
    TextView textview_sex= (TextView) convertView.findViewById(R.id.text_sex);
    TextView textview_hobby= (TextView) convertView.findViewById(R.id.text_hobby);
    textview_name.setText(student.getName());
    textview_sex.setText(student.getSex());
    textview_hobby.setText(student.getHobby());
    imageview.setImageResource(student.getImg());
return convertView;
}

进化版：为了不建太多view占用太多内存，增加了一个ViewHolder，让它持有这几个控件，如果新建view就findid给ViewHolder并把它设置成标记，不新建就把这个标记取出来直接调用复制
@Override
public View getView(int position, View convertView, ViewGroup parent) {
    Student student=mData.get(position);
    ViewHolder vh=null;

if(convertView==null){
        vh=new ViewHolder();   //在这里创建对象是因为else中没有使用对象调用属性和方法，对象的有效范围只是if
        convertView=minflater.inflate(R.layout.simple_adpter,null);
        vh.imageview= (ImageView) convertView.findViewById(R.id.image_photo);
        vh. textview_name= (TextView) convertView.findViewById(R.id.text_name);
        vh. textview_sex= (TextView) convertView.findViewById(R.id.text_sex);
        vh. textview_hobby= (TextView) convertView.findViewById(R.id.text_hobby);
        convertView.setTag(viewHolder);
    }else{
        vh= (ViewHolder) convertView.getTag();
    }
    //共同部分
vh.textview_name.setText(student.getName());
    vh.textview_sex.setText(student.getSex());
    vh.textview_hobby.setText(student.getHobby());
    vh.imageview.setImageResource(student.getImg());
return convertView;
}
class ViewHolder{
    TextView textview_name;
    TextView textview_sex;
    TextView textview_hobby;
    ImageView imageview;
}

现在再新建一个选择水果，在规则布局上添加一个CheckButton，因为初始化数据时为了满屏用的for循环，对象重复出现了点击一个下面一片被选中

解决方法:在for循环中创建对象

private void gettData() {   //这是自定义adapter的activity中初始化List的方法
mFruit=new ArrayList<>();

for(int i=0;i<50;i++){
mFruit.add(new Fruit("苹果",R.mipmap.apple));
mFruit.add(new Fruit("橘子",R.mipmap.orange));
mFruit.add(new Fruit("草莓",R.mipmap.berry));
    }
本来出错：

caomei=new Fruit("草莓",R.mipmap.berry)
for(····){
mFruit.add(caomei);//for出来的都是一个对象
}

   在规则布局文件中写focusable屏蔽CheckBox吃掉不属于它的点击
    android:gravity="center_vertical">
    <CheckBox
android:id="@+id/checkbox_fruit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:focusable="false"    //防止Button、CheckBox吃掉属于listView的点击事件
android:text="选择水果"/>
    <ImageView
android:id="@+id/imageview_fruit"
android:layout_width="100dp"
android:layout_height="100dp"
/>
    <TextView
android:id="@+id/textview_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="水果名称"/>
</LinearLayout>
源代码：（注意全局变量）

/**
 * Fruitadapter.java
 */
public class Fruitadapter extends BaseAdapter {
private LayoutInflater mInflater;
private List<Fruit> mFruits;
private boolean[] mManagerAllCheckedBox;//控制所有checkbox，初始值全为false

public Fruitadapter(LayoutInflater mInflater, List<Fruit> mFruits) {
this.mInflater = mInflater;
this.mFruits = mFruits;
mManagerAllCheckedBox = new boolean[mFruits.size()];//数据多少它就多少，初始化mFruit之后再初始化数组，不然空指针
    }

@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) {
        Fruit fruit = mFruits.get(position);
        ViewHolder viewHolder = null;
if (convertView == null) {
            viewHolder = new ViewHolder();
            convertView = mInflater.inflate(R.layout.item_fruit, null);
            viewHolder.checkBox = (CheckBox) convertView.findViewById(R.id.checkbox_fruit);
            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();
        }
        viewHolder.textView.setText(fruit.getName());
        viewHolder.imageView.setImageResource(fruit.getImg());
        viewHolder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
mManagerAllCheckedBox[position] = isChecked;
                notifyDataSetChanged();//用来更新屏幕（一个对象创建好几遍点一个另一个不立即反应说明屏幕不刷新）
}
        });
        viewHolder.checkBox.setChecked(mManagerAllCheckedBox[position]);
//当下一页时对象就改变了，所以没检测到点击，值是false用于刷新来自convertView的checkbox状态（不能放在监听前面，前面就不会刷新了）
return convertView;
    }

public void itemposition(int position) {  //在listView点击事件中调用，点一下CheckBox状态取反
mManagerAllCheckedBox[position] = !mManagerAllCheckedBox[position];//得到本行的水果对象
notifyDataSetChanged();
    }

public void checkedall() {    //在增加的HeaderView中的全选按钮点击时调用，全选中
for (int i = 0; i < mFruits.size(); i++) {
mManagerAllCheckedBox[i] = true;
            notifyDataSetChanged();
        }
    }

public void fanxuan() {        //在增加的FooterView中的反选按钮调用，全部反选
for (int i = 0; i < mFruits.size(); i++) {
mManagerAllCheckedBox[i] = !mManagerAllCheckedBox[i];
            notifyDataSetChanged();
        }
    }

class ViewHolder {
        ImageView imageView;
        CheckBox checkBox;
        TextView textView;
    }
}
/**
*
FruitcheckActivity.java  
其中增加了HeaderView和FooterView
*/
public class FruitcheckActivity extends ActionBarActivity {
private ListView listView;
private List<Fruit> mFruit;
private Fruitadapter mFruitadapter;
private LayoutInflater inflater;
private View mHeaderView;
private Button mBtnCheckedAll;
private View mFooterView;
private Button mBtnFanxuan;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_fruitcheck);//这个布局跟自定义时候一样里面只有一个listView
listView = (ListView) findViewById(R.id.list_fruit);
inflater = getLayoutInflater();
增加HeaderView和FooterView，其中加入全选和反选按钮，跟adapter中的规则布局一样都是关联布局文件  
mHeader View= inflater.inflate(R.layout.layout_all, null);
mBtnCheckedAll = (Button) mHeaderView.findViewById(R.id.button_checked_all);
mBtnCheckedAll.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mFruitadapter.checkedall();
            }
        });
listView.addHeaderView(mHeader);
mFooter = inflater.inflate(R.layout.layout_fan, null);
mBtnFanxuan = (Button) mFooter.findViewById(R.id.button_fanxuan);
mBtnFanxuan.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mFruitadapter.fanxuan();
            }
        });
listView.addFooterView(mFooter);
    
    gettData();
mFruitadapter = new Fruitadapter(inflater, mFruit);
listView.setAdapter(mFruitadapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
//给listView增加一个点击事件，跟button不同，是itemCliklistener
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
mFruitadapter.itemposition(position - 1);//adapter对象改成全局变量，把position传过去
}
        });
    }
private void gettData() {
mFruit = new ArrayList<>();
for (int i = 0; i < 10; i++) {
mFruit.add(new Fruit("苹果", R.mipmap.apple));
mFruit.add(new Fruit("橘子", R.mipmap.orange));
mFruit.add(new Fruit("草莓", R.mipmap.berry));
        }
    }
}

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