Android　ListView 事件监听 || 关于ListView选中时显示的效果。

Android　ListView 事件监听 || 关于ListView选中时显示的效果。

AndroidUIXML.netthread
Adapter是用来帮助填充数据的中间桥梁，比如通过它将数据填充到ListView, GridView, Gallery.而android 提供了几种Adapter:ArrayAdapter<T>, BaseAdapter, CursorAdapter, HeaderViewListAdapter, ListAdapter, ResourceCursorAdapter, SimpleAdapter, SimpleCursorAdapter,
SpinnerAdapter, WrapperListAdapter.我猜想这些Adapter的区别在于你的数据来源不一样：比如若你的数据来源于一个Arraylist 就使用BaseAdapter,SimpleAdapter,而数据来源于通过查询数据库获得Cursor那就使用SimpleCursorAdapter等。就目前我经常使用的BaseAdapter和SimpleCursorAdapter。

1，BaseAdapter:---数据来源于Arraylist-->MyArraylist

当你继承BaseAdapter客制化你的Adapter时，你必须OverWrite以下函数：

Java代码

@Override
public int getCount() {
// TODO Auto-generated method stub

System.out.println("the size is\t" + MyArraylist.size());
return MyArraylist.size();
}

@Override
public int getCount() {
// TODO Auto-generated method stub
System.out.println("the size is\t" +            MyArraylist.size());
return MyArraylist.size();
}

getCount返回的就是你的有多少条数据需要绑定的，也就是需要多少个View.比如这里返回的就是MyArraylist的Size.

Java代码

public View getView(int position, View v, ViewGroup parent) { // TODO Auto-generated method stub View view; if (v == null) { view = mInflater.inflate(R.layout.track_list_item, null); } else { view = v; }}

public View getView(int position, View v, ViewGroup parent) {
// TODO Auto-generated method stub

View view;
if (v == null) {
view = mInflater.inflate(R.layout.track_list_item, null);
} else {
view = v;
}}

通过getView就获得了view来显示数据了。在这里你就可以自定义你的View了，但你通过XML定义可以通过LayoutInflater来inflater你的XML。getView里面就可以将MyArraylist的数据通过position 这个来将数据一条绑定一个View了。

2,SimpleCursorAdapter：---数据来源于数据库--->MyCursor

转自：http://blog.csdn.net/wong_judy/archive/2010/04/09/5466583.aspx

要实现bindView()和newView()这两个抽象方法需要实现的内容。

public void bindView(View view, Context context, Cursor cursor)，重用一个已有的view，使其显示当前cursor所指向的数据。

public View newView(Context context, Cursor cursor, ViewGroup parent)，为cursor所指向的数据新建一个View对象，并显示其数据。

通俗的说：比如你一个listview在一个屏幕里一次只能显示8条数据，那么第一次显示的时候就会newView 8次生成8个View,调用bindView绑定8条数据，而你有16条数据，但你拖动滚动条看9-16条时，此时不会再调用newView了，而只能调用了bindView去绑定新的数据而了。这样就省了空间了。

注意：传入到CursorAdapter中的Cursor结果集必须包含有列名为_id的列，否则SimpleCursorAdapter将不会起作用。

对于SimpleCursorAdapter中的newView与bindView的作用在BaseAdapter中的getView中也有这样的意义：getView里面我们必须做判断才能达到这种效果，就是要判断第二个参数View的是否为空：当空时就Infalte新的View，但不为空时就要就用它，这样就第一屏幕Infate 8个View，后面就直接使用这个8个view了。

注意：getView中是返回一个view，必须返回的是你infalte之后不为空的View，不然会报空指针异常。

==================================================================



关于ListView选中时显示的效果。

方法一：



通过给listview设置 android:listSelector这个属性，就可以对其下的所有item设定state_focused 时的背景变化

方法二：

实际上很简单，就是点击一下改变listviewitem的背景

Java代码

public void changeBg(int position){ isFocused[whichClick==-1?0:whichClick] = false; whichClick = position; isFocused[position] = true; notifyDataSetChanged(); }

public void changeBg(int position){

isFocused[whichClick==-1?0:whichClick] = false;

whichClick = position;

isFocused[position] = true;

notifyDataSetChanged();
}

转载自： http://www.eoeandroid.com/thread-52160-1-1.html

Java代码

package com.ui.demo;
import java.util.List;
import java.util.Map;

import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MyArrayAdapter extends BaseAdapter{

private static List<Map<String,String>> list;

private LayoutInflater mInflater;

private ViewHolder holder;
//alertdialog 被选中初始化false
private static boolean[] isFocused ;

private static int whichClick = -1;
Context mContext;
public MyArrayAdapter(Context context,List<Map<String,String>> objects){

list = objects;
mContext = context;
mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

isFocused = new boolean[objects.size()];

for(int i=0;i<objects.size();i++){

isFocused[i] = false;
}
}

public int getCount() {

return list.size();
}

public Object getItem(int position) {

return list.get(position);
}

public long getItemId(int position) {

return position;
}

public void changeBg(int position){ isFocused[whichClick==-1?0:whichClick] = false; whichClick = position; isFocused[position] = true; notifyDataSetChanged(); }public View getView(int position, View convertView, ViewGroup parent) {

if (convertView == null) {

convertView = mInflater.inflate(R.layout.musiccategories, null);

holder = new ViewHolder();

holder.s_Name = (TextView) convertView.findViewById(R.id.s_name);
holder.btnTest = (Button) convertView.findViewById(R.id.btnTest);
holder.btnTest.setText("Kaden");
holder.btnTest.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
Toast.makeText(mContext, "Button clicked.", Toast.LENGTH_SHORT).show();

}
});

convertView.setTag(holder);
} else {
// Get the ViewHolder back to get fast access to the TextView

// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}

convertView.setBackgroundResource(isFocused[position]?R.drawable.btn_down_bg:R.drawable.btn_up_bg);

//holder.s_Name.setText(list.get(position).get(WebTools.SON_GEMING));

return convertView;
}

static class ViewHolder {

TextView s_Name;
Button btnTest;
}
}

package com.ui.demo;
import java.util.List;
import java.util.Map;

import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MyArrayAdapter extends BaseAdapter{

private static List<Map<String,String>> list;

private LayoutInflater mInflater;

private ViewHolder holder;
//alertdialog 被选中初始化false
private static boolean[] isFocused ;

private static int whichClick = -1;
Context mContext;
public MyArrayAdapter(Context context,List<Map<String,String>> objects){

list = objects;
mContext = context;
mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

isFocused = new boolean[objects.size()];

for(int i=0;i<objects.size();i++){

isFocused[i] = false;
}
}

public int getCount() {

return list.size();
}

public Object getItem(int position) {

return list.get(position);
}

public long getItemId(int position) {

return position;
}

public void changeBg(int position){

isFocused[whichClick==-1?0:whichClick] = false;

whichClick = position;

isFocused[position] = true;

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

if (convertView == null) {

convertView = mInflater.inflate(R.layout.musiccategories, null);

holder = new ViewHolder();

holder.s_Name = (TextView) convertView.findViewById(R.id.s_name);
holder.btnTest = (Button) convertView.findViewById(R.id.btnTest);
holder.btnTest.setText("Kaden");
holder.btnTest.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
Toast.makeText(mContext, "Button clicked.", Toast.LENGTH_SHORT).show();

}
});

convertView.setTag(holder);
} else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}

convertView.setBackgroundResource(isFocused[position]?R.drawable.btn_down_bg:R.drawable.btn_up_bg);

//holder.s_Name.setText(list.get(position).get(WebTools.SON_GEMING));

return convertView;
}

static class ViewHolder {

TextView s_Name;
Button btnTest;
}
}

Java代码

package com.ui.demo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.AdapterView.OnItemClickListener;

/**
* @Title: ListviewTest.java
* @Package com.ui.demo
* @Description: TODO
* @author Kaden Kang E-mail:cumtkangyi@gmail.com

* @version Create date: 2010-11-29下午12:10:13

* @version V1.0
*/

public class ListviewTest extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub

super.onCreate(savedInstanceState);
setContentView(R.layout.my_listview);

List<Map<String, String>> listItem = new ArrayList<Map<String, String>>();
Map<String, String> map;
map = new HashMap<String, String>();
map.put("ItemTitle", "China");
map.put("ItemInfo", "+86");
listItem.add(map);
map = new HashMap<String, String>();
map.put("ItemTitle", "Iran");
map.put("ItemInfo", "+98");
listItem.add(map);
map = new HashMap<String, String>();
map.put("ItemTitle", "Iraq");
map.put("ItemInfo", "+964");
listItem.add(map);
map = new HashMap<String, String>();
map.put("ItemTitle", "Ireland");
map.put("ItemInfo", "+353");
listItem.add(map);
map = new HashMap<String, String>();
map.put("ItemTitle", "Israel");
map.put("ItemInfo", "+972");
listItem.add(map);
map = new HashMap<String, String>();
map.put("ItemTitle", "American");
map.put("ItemInfo", "+001");
listItem.add(map);

ListView listView = (ListView)findViewById(R.id.mListView);
final MyArrayAdapter adapter = new MyArrayAdapter(this, listItem);
listView.setAdapter(adapter);

listView.setOnItemClickListener(new OnItemClickListener() {

@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
adapter.changeBg(arg2);

}
});
}

}

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