你真的了解Android ListView吗？
---------------------------------------------------------------------------
什么是Android ListView？
ListView是一个显示可滚动的项目列表视图组。 该列表中的项目使用的是自动插入到列表Adapter ，拉从源内容，如数组或数据库查询，把每个项目导如成被放置到列表的视图。 在android开发中ListView是比较常用的组件，它以列表的形式展示具体内容，并且能够根据数据的长度自适应显示。 说到ListView就不得不说Adapter适配器，因为只有通过Adapter才可以把列表中的数据映射到ListView中。 在android的开发中最Adapter 一共可以分为- ArrayAdapter<T>
- BaseAdapter
- CursorAdapter
- HeaderViewListAdapter
- ResourceCursorAdapter
- SimpleAdapter
- SimpleCursorAdapter
- WrapperListAdapter
ListView的实例
简单的ListView
在List列表中如果不存在过于复杂的东西 我们可以直接去new ArrayAdapter() 来绘制列表，无须继承ArrayAdapter，重写它的方法。但是如果列表中过于复杂的话就需要使用自定义布局来实现List列表。
```
public class SimpleList extends ListActivity {
private String[] mListStr = {"姓名：哈哈","性别：男","年龄：25","居住地：北京","邮箱：haha@gmail.com"};
ListView mListView = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
mListView = getListView();
setListAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, mListStr));
mListView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position,
long id) {
Toast.makeText(SimpleList.this,"您选择了" + mListStr[position], Toast.LENGTH_LONG).show();
}
});
super.onCreate(savedInstanceState);
}
}
```
带标题的ListView列表
使用 simpleAdapter 需要注意的是须要用`Map<String,Object> item` 来保存列表中每一项的显示的title与text , new SimpleAdapter的时候将map中的数据写入 ，程序就会帮我们绘制列表了。 ``` public class TitleList extends ListActivity { private String[] mListTitle = { "姓名", "性别", "年龄", "居住地","邮箱"}; private String[] mListStr = { "哈哈", "男", "25", "北京", "haha@gmail.com" }; ListView mListView = null; ArrayList<Map<String,Object>> mData= new ArrayList<Map<String,Object>>();; @Override protected void onCreate(Bundle savedInstanceState) { mListView = getListView(); int lengh = mListTitle.length; for(int i =0; i < lengh; i++) { Map<String,Object> item = new HashMap<String,Object>(); item.put("title", mListTitle[i]); item.put("text", mListStr[i]); mData.add(item); } SimpleAdapter adapter = new SimpleAdapter(this,mData,android.R.layout.simple_list_item_2, new String[]{"title","text"},new int[]{android.R.id.text1,android.R.id.text2}); setListAdapter(adapter); mListView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) { Toast.makeText(TitleList.this,"您选择了标题：" + mListTitle[position] + "内容："+mListStr[position], Toast.LENGTH_LONG).show(); } }); super.onCreate(savedInstanceState); } } ```带图片的ListView列表
使用 simpleAdapter 来操作 但是构造simpleAdapter的时候须要使用我们自己写的布局来完成 ，因为系统的布局已经不能满足需求了，同样`Map<String,Object> item` 来保存列表中每一项须要的显示内容 如 图片 标题 内容等。 activity_main.xml ``` <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="?android:attr/listPreferredItemHeight"> <ImageView android:id="@+id/image" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentTop="true" android:layout_alignParentBottom="true" android:adjustViewBounds="true" android:padding="2dip" /> <TextView android:id="@+id/title" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_toRightOf="@+id/image" android:layout_alignParentRight="true" android:layout_alignParentTop="true" android:layout_above="@+id/text" android:layout_alignWithParentIfMissing="true" android:gravity="center_vertical" android:textSize="15dip" /> <TextView android:id="@+id/text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/image" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="20dip" /> </RelativeLayout> ``` MainActivity.java ``` public class MainActivity extends ListActivity { private String[] mListTitle = { "姓名", "性别", "年龄", "居住地","邮箱"}; private String[] mListStr = { "哈哈", "男", "25", "北京", "haha@gmail.com" }; ListView mListView = null; ArrayList<Map<String,Object>> mData= new ArrayList<Map<String,Object>>();; @Override protected void onCreate(Bundle savedInstanceState) { mListView = getListView(); int lengh = mListTitle.length; for(int i =0; i < lengh; i++) { Map<String,Object> item = new HashMap<String,Object>(); item.put("image", R.drawable.jay); item.put("title", mListTitle[i]); item.put("text", mListStr[i]); mData.add(item); } SimpleAdapter adapter = new SimpleAdapter(this,mData,R.layout.iconlist, new String[]{"image","title","text"},new int[]{R.id.image,R.id.title,R.id.text}); setListAdapter(adapter); mListView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) { Toast.makeText(IconList.this,"您选择了标题：" + mListTitle[position] + "内容："+mListStr[position], Toast.LENGTH_LONG).show(); } }); super.onCreate(savedInstanceState); } } ```自定义布局BaseAdapter修改列表颜色
因为通过直接 构造系统的布局来绘制列表方法肯定是有限的，所以我们需要重写绘制方法 ，写一个类去继承BaseAdapter 并实现这个类中的方法，listView在一开始绘制的时候首先会调用getCout()方法得到绘制次数 ，然后会实例化自己定义的BaseAdapter通过getView()方法一层一层绘制ListView,所以我们可以在这里面根据position(当前绘制的ID)来任意的修改绘制的内容，做出好看漂亮的ListView,下面这个例子我通过重写getView修改每个列表的颜色 并且实现用户选中后成高亮状态。 activity_main.xml ``` <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content"> <ImageView android:id="@+id/color_image" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentTop="true" android:layout_alignParentBottom="true" android:adjustViewBounds="true" android:padding="2dip" /> <TextView android:id="@+id/color_title" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/color_image" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="15dip" /> <TextView android:id="@+id/color_text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/color_image" android:layout_below="@+id/color_title" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="20dip" /> </RelativeLayout> ``` MianActivity.java ``` public class MianActivity extends ListActivity { private String[] mListTitle = { "姓名", "性别", "年龄", "居住地","邮箱"}; private String[] mListStr = { "哈哈", "男", "25", "北京", "haha@gmail.com" }; ListView mListView = null; MyListAdapter myAdapter = null; @Override protected void onCreate(Bundle savedInstanceState) { mListView = getListView(); myAdapter = new MyListAdapter(this); setListAdapter(myAdapter); mListView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) { View v=adapterView.getChildAt(position); v.setBackgroundColor(Color.RED); Toast.makeText(ColorList.this,"您选择了" + mListStr[position], Toast.LENGTH_LONG).show(); } }); super.onCreate(savedInstanceState); } class MyListAdapter extends BaseAdapter { private int[] colors = new int[] { 0xff626569, 0xff4f5257 }; public MyListAdapter(Context context) { mContext = context; } public int getCount() { return mListStr.length; } @Override public boolean areAllItemsEnabled() { return false; } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { ImageView iamge = null; TextView title = null; TextView text = null; if (convertView == null) { convertView = LayoutInflater.from(mContext).inflate(R.layout.colorlist, null); iamge = (ImageView) convertView.findViewById(R.id.color_image); title =(TextView) convertView.findViewById(R.id.color_title); text= (TextView) convertView.findViewById(R.id.color_text); } int colorPos = position % colors.length; convertView.setBackgroundColor(colors[colorPos]); title.setText(mListTitle[position]); text.setText(mListStr[position]); iamge.setImageResource(R.drawable.jay); return convertView; } private Context mContext; } } ```自定义布局ArrayAdapter
ArrayAdapter是BaseAdapter的子类，ArrayAdapter不仅具有BaseAdapter的所有方法还自定义了一些新的方法来处理列表项，所以单纯的从功能能上来讲ArrayAdapter远远强与BaseAdapter，如果是绘制一些数量比较少的列表建议使用BaseAdapter 如果绘制一些比较复杂的列表项 并且列表项很多的 建议使用ArrayAdapter。 activity_main.xml ``` <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content"> <Button android:id="@+id/array_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="用户" /> <ImageView android:id="@+id/array_image" android:layout_toRightOf="@+id/array_button" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentTop="true" android:layout_alignParentBottom="true" android:adjustViewBounds="true" android:padding="2dip" /> <TextView android:id="@+id/array_title" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/array_image" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="15dip" /> <TextView android:id="@+id/array_text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/array_image" android:layout_below="@+id/array_title" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="20dip" /> </RelativeLayout> ``` MianActivity.java ``` public class ArrayList extends ListActivity { private String[] mListTitle = { "姓名", "性别", "年龄", "居住地","邮箱"}; private String[] mListStr = { "哈哈", "男", "25", "北京", "haha@gmail.com" }; ListView mListView = null; MyListAdapter myAdapter = null; ArrayList arrayList = null; @Override protected void onCreate(Bundle savedInstanceState) { arrayList = this; mListView = getListView(); myAdapter = new MyListAdapter(this,R.layout.arraylist); setListAdapter(myAdapter); super.onCreate(savedInstanceState); } public class MyListAdapter extends ArrayAdapter<Object> { int mTextViewResourceID = 0; private Context mContext; public MyListAdapter(Context context, int textViewResourceId) { super(context, textViewResourceId); mTextViewResourceID = textViewResourceId; mContext = context; } private int[] colors = new int[] { 0xff626569, 0xff4f5257 }; public int getCount() { return mListStr.length; } @Override public boolean areAllItemsEnabled() { return false; } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(final int position, View convertView, ViewGroup parent) { ImageView iamge = null; TextView title = null; TextView text = null; Button button = null; if (convertView == null) { convertView = LayoutInflater.from(mContext).inflate( mTextViewResourceID, null); iamge = (ImageView) convertView.findViewById(R.id.array_image); title = (TextView) convertView.findViewById(R.id.array_title); text = (TextView) convertView.findViewById(R.id.array_text); button = (Button)convertView.findViewById(R.id.array_button); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { Toast.makeText(arrayList,"您点击的第"+position +"个按钮", Toast.LENGTH_LONG).show(); } }); } int colorPos = position % colors.length; convertView.setBackgroundColor(colors[colorPos]); title.setText(mListTitle[position]); text.setText(mListStr[position]); if(colorPos == 0) iamge.setImageResource(R.drawable.jay); else iamge.setImageResource(R.drawable.image); return convertView; } } } ```---------------------------------------------------------------------------
没有评论:
发表评论