Android 中适配器有很多,我今天来讲讲比较常用的ArrayAdapter实现listview的增删查。
步骤一:创建一个实体类,作为ListView适配器的适配类型
public class Fruit implements Serializable{
private String name;
private int img;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getImg() {
return img;
}
public void setImg(int img) {
this.img = img;
}
public Fruit(String name, int img) {
this.name = name;
this.img = img;
}
}
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
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_height="wrap_content"
android:layout_width="match_parent"
></ListView>
</LinearLayout>
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>
步骤三:创建一个自定义的适配器,这个适配器需要继承ArrayAdapter其泛型指向Fruitt
public class FruitAdapter extends ArrayAdapter<Fruit>{
private MainActivity mainActivity;
private int resourceid;
public FruitAdapter(MainActivity context, int resource, List<Fruit> objects) {
super(context, resource, objects);
// TODO Auto-generated constructor stub
this.mainActivity=context;
this.resourceid=resource;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
ViewHolder holder;
View view;
if (convertView==null) {
view=LayoutInflater.from(getContext()).inflate(resourceid, null);
holder=new ViewHolder();
holder.iv=(ImageView) view.findViewById(R.id.iv);
holder.tv=(TextView) view.findViewById(R.id.tv);
holder.btn=(Button) view.findViewById(R.id.btn);
view.setTag(holder);
}else {
view=convertView;
holder=(ViewHolder) view.getTag();
}
Fruit fruit=getItem(position);
holder.iv.setImageResource(fruit.getImg());
holder.tv.setText(fruit.getName());
holder.btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mainActivity.removeIt(position);
//notifyDataSetChanged();
}
});
return view;
}
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 List<Fruit> all = new ArrayList<Fruit>();
private ListView lv;
private FruitAdapter adapter;
private Button btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.list);
initData();//初始化水果数据
lv = (ListView) findViewById(R.id.lv);
btn = (Button) findViewById(R.id.btn);
adapter = new FruitAdapter(MainActivity.this, R.layout.item, all);
lv.setAdapter(adapter);
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
addItem();
}
});
// initData();
}
public void initData() {
Fruit fruit = new Fruit("a", R.drawable.a);
all.add(fruit);
Fruit fruitb = new Fruit("b", R.drawable.b);
all.add(fruitb);
Fruit fruitc = new Fruit("c", R.drawable.c);
all.add(fruitc);
Fruit fruitd = new Fruit("d", R.drawable.d);
all.add(fruitd);
Fruit fruit1 = new Fruit("a", R.drawable.a);
all.add(fruit1);
Fruit fruitb2 = new Fruit("b", R.drawable.b);
all.add(fruitb2);
Fruit fruitc3 = new Fruit("c", R.drawable.c);
all.add(fruitc3);
Fruit fruitd4 = new Fruit("d", R.drawable.d);
all.add(fruitd4);
Fruit a = new Fruit("a", R.drawable.a);
all.add(a);
Fruit b = new Fruit("a", R.drawable.a);
all.add(b);
Fruit c = new Fruit("a", R.drawable.a);
all.add(c);
Fruit d = new Fruit("a", R.drawable.a);
all.add(d);
Fruit e = new Fruit("a", R.drawable.a);
all.add(e);
Fruit f = new Fruit("a", R.drawable.a);
all.add(f);
}
// 在adapter类里点击删除按钮时调用这个方法
public void removeIt(int position) {
all.remove(position);
adapter.notifyDataSetChanged();
}
// 点击“添加一个item”按钮时调用这个方法
public void addItem() {
Fruit f = new Fruit("新的item", R.drawable.a);
all.add(0, f);
// 及时刷新,不然出现不了数据
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。在getView代码中,我用了最好的提高listView提升运行效率的方式,代码在这,大家可以慢慢的去斟酌,感悟就是不是多看,是多敲代码。如还有不懂可给我留言。