Android常用组件之ListView

使用ListAdapter是ListView的适配器。

使用ListView.setAdapter()方法来设置ListView的适配器。

1. 简单的使用

adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1);

adapter.add("hello");

adapter.add("eoe");

lv.setAdapter(adapter);

R前面的android表示使用的是系统提供给我们的资源。

1. 使用自定义的资源

在layout包下新建一个XML，内容如下：

<?xml
version="1.0"
encoding="utf-8"?>

<ListView
xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"
>

</ListView>

然后如下所示，创建Adapter：

adapter = new ArrayAdapter<String>(this,R.layout.list_cell_view);

adapter.add("hello");

adapter.add("eoe");

lv.setAdapter(adapter);

1. 自定义Adapter

private BaseAdapter adapter = new BaseAdapter() {

        private String[] data = {"user1","user2","user3","user4","user5","user6",

    "user7","user8","user9","user10","user11","user12","user13","user14",};

    @Override

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

        TextView tv = new TextView(MainActivity.this);

        tv.setText(getItem(position));

        return tv;

    }

        

    @Override

    public
long getItemId(int position) {

        return position;

    }

        

    @Override

    public String getItem(int position) {

        return
data[position];

    }

        

    @Override

    public
int getCount() {

        return
data.length;

    }

};

程序运行时，界面上显示多少个列表项，getView方法就是被执行多少次。

getView参数中的View表示被系统回收的View。

优化：

TextView tv = null;

if (convertView!=null){

    tv = (TextView) convertView;

}else {

    tv = new TextView(MainActivity.this);

}

tv.setText(getItem(position));

1. 创建一个可以显示图片的ListView

在layout中新建一个Linearlayout布局的文件：

<?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"

android:orientation="horizontal"
>

<ImageView

android:layout_width="120dp"

android:layout_height="120dp"

android:id="@+id/icon"/>

<LinearLayout

android:layout_weight="1"

android:layout_width="0dp"

android:layout_height="match_parent"

android:orientation="vertical">

<TextView

android:id="@+id/name"

android:layout_width="wrap_content"

android:layout_height="wrap_content"/>

<TextView

android:id="@+id/dec"

android:layout_width="wrap_content"

android:layout_height="wrap_content"/>

</LinearLayout>

 

</LinearLayout>

创建一个Adapter：

private BaseAdapter adapter = new BaseAdapter() {

private ListCellData[] data = new ListCellData[]{

    new ListCellData("小明",     "男", android.R.drawable.ic_btn_speak_now),

    new ListCellData("小丽",     "女", android.R.drawable.ic_dialog_dialer),

};

    @Override

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

        LinearLayout line = null;

        if (convertView!=null){

            line = (LinearLayout) convertView;

        }else {

            line = (LinearLayout) LayoutInflater.from(MainActivity.this).inflate(R.layout.list_cell_view, null);

        }

        ListCellData item = getItem(position);

        ImageView image = (ImageView) line.findViewById(R.id.icon);

        TextView name = (TextView) line.findViewById(R.id.name);

        TextView dec = (TextView) line.findViewById(R.id.dec);

        image.setImageResource(item.getIcon());

        name.setText(item.getUsername());

        dec.setText(item.getSex());

        return line;

    }

        

    @Override

    public
long getItemId(int position) {

        return position;

    }

        

    @Override

    public ListCellData getItem(int position) {

        return
data[position];

    }

    

    @Override

    public
int getCount() {

        return
data.length;

    }

};