對於初學者來說,接觸到listview的時候,通常使用適配器都是簡單的ArrayAdapter適配器,最多就使用simpleAdapter 這兩個適配器,但對於自定義Adapter的時候,我們通常都會自己寫了一個類繼承baseadapter,那麼瞭解baseadapter
android.widget.BaseAdapter
BaseAdapter的四個方法:
/*
*顯示視圖
*/
@Override
public View getView(int position, View convertView, ViewGroup parent) {
return null;
}
/*
*獲取第幾個條數據的ID
*/
@Override
public long getItemId(int position) {
return 0;
}
/*
*獲取第幾條數據
*/
@Override
public Object getItem(int position) {
return null;
}
/*
*獲取數據 的數量
*/
@Override
public int getCount() {
return 0;
}
下面就列舉一個listview使用baseadapter的例子1,先在activity_mian.xml寫一個listview佈局
<?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"
android:orientation="vertical" >
<TextView
android:id="@+id/textView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="TextView" />
</LinearLayout>
我就放了一個textview,如果你想複雜點,可以再繼續佈局多幾個控件
3,那麼佈局文件有了,還差一個適配器,現在新建一個類MyAdapter繼承BaseAdapter
public class MyAdapter extends BaseAdapter{
private List<String>mlist; //接受MainActivity傳過來的數據
private Context mContext;
private LayoutInflater mLayout;
public MusicAdapter( List<String>list,Context context){
this.mList=list;
this.mContext=context;
this.mLayout=LayoutInflater.from(context);
}
@Override
public int getCount() {
return mList.size();
}
@Override
public Object getItem(int position) {
return mList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder mViewHolder;
if(convertView==null){
mViewHolder=new ViewHolder();
convertView=mLayout.inflate(R.layout.list_item, null);
mViewHolder.text=(TextView) convertView.findViewById(R.id.textView1);
convertView.setTag(mViewHolder);
}else{
mViewHolder=(ViewHolder) convertView.getTag();
}
mViewHolder.text.setText(mList.get(position));
return convertView;
}
class ViewHolder{
private TextView text;
}
}
差在MainActivity.java文件呈現出自定義的listview了
public class MainActivity extends Activity{
private ListView mListView;
private List<String> mlist;
private MyAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContextView(R.layout.activity_main);
setListData();
initView();
}
private void setListData(){
mList=new ArrayList<String>();
mList.add("星期一");
mList.add("星期二");
mList.add("星期三");
mList.add("星期四");
mList.add("星期五");
mList.add("星期六");
mList.add("星期日");
}
private void initView() {
mListView=(LIstView)findViewById(R,id.listview);
mAdapter=new MyAdapter(mList,MainActivity.this);
mListView.setAdapter(mAdapter);
}
}