自学安卓复习基础_之十（使用适配器BaseAdapter来实现listView的CRD）

和上一个例子是一样的，只是使用不同的方式实现。自定义的adapter继承BaseAdapter，好啦，看代码吧。都是些简单的例子，希望能帮到刚在学习安卓的童鞋！



步骤一：创建一个实体类，作为ListView适配器的适配类型

public class Fruit {
private String name;
private int imgeid;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getImgeid() {
return imgeid;
}
public void setImgeid(int imgeid) {
this.imgeid = imgeid;
}
public Fruit(String name, int imgeid) {

this.name = name;
this.imgeid = imgeid;
}

}

步骤二：创建两个layout布局，一个是listView的子项布局，一个是listview页面布局

item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ImageView
android:id="@+id/iv"
android:layout_height="80dp"
android:layout_width="80dp"
android:src="@drawable/d"
/>
<TextView
android:id="@+id/tv"
android:layout_height="80dp"
android:layout_width="0dp"
android:layout_weight="1"
android:text="hahhaha"
android:gravity="center"
/>

<Button
android:id="@+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="删除" />

</LinearLayout>

list.xml

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

<Button
android:id="@+id/btn"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="添加一个item" />

<ListView
android:id="@+id/lv"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</ListView>

</LinearLayout>

步骤三：创建一个自定义的适配器，这个适配器需要继承BaseAdapter

public class FruitAdapter extends BaseAdapter{

private List<Fruit> all;
private MainActivity activity;
private LayoutInflater inflate=null;
public FruitAdapter(List<Fruit> all,MainActivity context) {
inflate=LayoutInflater.from(context);
this.all=all;
this.activity=context;

}
@Override
public int getCount() {
// 获取到集合的总数
return all.size();
}

@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}

@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}

@SuppressLint("InflateParams")
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView==null) {
convertView=inflate.inflate(R.layout.item, null);
holder=new ViewHolder();
holder.iv=(ImageView) convertView.findViewById(R.id.iv);
holder.tv=(TextView) convertView.findViewById(R.id.tv);
holder.btn=(Button) convertView.findViewById(R.id.btn);
convertView.setTag(holder);
}else {
holder=(ViewHolder) convertView.getTag();
}
Fruit f=all.get(position);
holder.iv.setImageResource(f.getImgeid());
holder.tv.setText(f.getName());
holder.btn.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
activity.delData(position);
}
});
return convertView;
}

class ViewHolder{
private ImageView iv;
private TextView tv;
private Button btn;
}
}

步骤四：完成修改MainActivity的代码

public class MainActivity extends Activity{

private ListView lv;
private List<Fruit> all;
private FruitAdapter adapter;
private Button btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.list);
all=initData();
lv=(ListView) findViewById(R.id.lv);
adapter=new FruitAdapter(all, MainActivity.this);
btn=(Button) findViewById(R.id.btn);
lv.setAdapter(adapter);
btn.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
add();
}
});
}
private List<Fruit> initData(){
List<Fruit> list=new ArrayList<Fruit>();
Fruit f=new Fruit("haha1", R.drawable.a);
list.add(f);
Fruit q=new Fruit("haha2", R.drawable.b);
list.add(q);
Fruit a=new Fruit("haha3", R.drawable.c);
list.add(a);
Fruit b=new Fruit("haha4", R.drawable.d);
list.add(b);
Fruit c=new Fruit("haha5", R.drawable.a);
list.add(c);
Fruit d=new Fruit("haha6", R.drawable.a);
list.add(d);
return list;
}
public void delData(int position){
all.remove(position);
adapter.notifyDataSetChanged();
}
private void add(){
Fruit d=new Fruit("新增的item", R.drawable.a);
all.add(0,d);
adapter.notifyDataSetChanged();
}
}

步骤五：最后不要忘记在清单文件中注册MainActivity哦。这样就完成了简单的增删查啦。