Java 筛选SimpleAdapter时出现NullPointerException
问题:我只想在Java 筛选SimpleAdapter时出现NullPointerException,java,android,filter,arraylist,simpleadapter,Java,Android,Filter,Arraylist,Simpleadapter,问题:我只想在列表视图中过滤或搜索该项目,但我总是会出现此错误“java.lang.NullPointerException”。请帮我解决这个问题 播放活动。java: package com.name.musicplayer; import java.util.ArrayList; import java.util.HashMap; import com.androidhive.musicplayer.PlayListActivity; import android.app.ListActi
列表视图中过滤或搜索该项目,但我总是会出现此错误“java.lang.NullPointerException”
。请帮我解决这个问题
播放活动。java:
package com.name.musicplayer;
import java.util.ArrayList;
import java.util.HashMap;
import com.androidhive.musicplayer.PlayListActivity;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class PlayListActivity extends ListActivity {
// Songs list
public ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
//list view adapter
ArrayAdapter<String> adapter_l;
// Search EditText
EditText inputSearch;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.playlist);
inputSearch = (EditText) findViewById(R.id.inputSearch);
ArrayList<HashMap<String, String>> songsListData = new ArrayList<HashMap<String, String>>();
SongsManager plm = new SongsManager();
// get all songs from sdcard
this.songsList = plm.getPlayList();
// looping through playlist
for (int i = 0; i < songsList.size(); i++) {
// creating new HashMap
HashMap<String, String> song = songsList.get(i);
// adding HashList to ArrayList
songsListData.add(song);
}
// Adding menuItems to ListView
ListAdapter adapter = new SimpleAdapter(this, songsListData,
R.layout.playlist_item, new String[] { "songTitle" }, new int[] {
R.id.songTitle });
setListAdapter(adapter);
met_play_song_on_list();
met_search();
}
private void met_play_song_on_list() {
// TODO Auto-generated method stub
// selecting single ListView item
ListView lv = getListView();
// listening to single listitem click
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting listitem index
int songIndex = position;
// Starting new intent
Intent in = new Intent(getApplicationContext(),
AndroidBuildingMusicPlayerActivity.class);
// Sending songIndex to PlayerActivity
in.putExtra("songIndex", songIndex);
setResult(100, in);
// Closing PlayListView
finish();
}
});
}
private void met_search() {
// TODO Auto-generated method stub
/**
* Enabling Search Filter
* */
inputSearch.addTextChangedListener(new TextWatcher() {
public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
// When user changed the Text
//PlayListActivity.this.adapter_l.getFilter().filter(cs);
}
public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
// TODO Auto-generated method stub
}
public void afterTextChanged(Editable arg0) {
// TODO Auto-generated method stub
PlayListActivity.this.adapter_l.getFilter().filter(arg0);
}
});
}
}
package com.name.musicplayer;
导入java.util.ArrayList;
导入java.util.HashMap;
导入com.androidhive.musicplayer.playlayer活动;
导入android.app.ListActivity;
导入android.content.Intent;
导入android.os.Bundle;
导入android.text.Editable;
导入android.text.TextWatcher;
导入android.view.view;
导入android.widget.AdapterView;
导入android.widget.AdapterView.OnItemClickListener;
导入android.widget.ArrayAdapter;
导入android.widget.EditText;
导入android.widget.ListAdapter;
导入android.widget.ListView;
导入android.widget.simpledapter;
公共类播放活动扩展了ListActivity{
//歌曲列表
public ArrayList songsList=new ArrayList();
//列表视图适配器
阵列适配器;
//搜索编辑文本
编辑文本输入搜索;
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.playlist);
inputSearch=(EditText)findViewById(R.id.inputSearch);
ArrayList songsListData=新的ArrayList();
SongsManager plm=新的SongsManager();
//从SD卡获取所有歌曲
this.songsList=plm.getPlayList();
//循环播放列表
对于(int i=0;i
下面是SongManager.java类:
package com.name.musicplayer;
import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import com.name.musicplayer.JSONParser;
public class SongsManager {
// SDCard Path
private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
// url to make request
private static String url = "http://domain.com/android/songlist.php";
// JSON Node names
private static final String TAG_str_song = "str_song";
private static final String TAG_str_song_name = "str_song_name";
private static final String TAG_str_song_path = "str_song_path";
// contacts JSONArray
JSONArray songslist = null;
// Constructor
public SongsManager() {
}
/**
* Function to read all mp3 files from sdcard and store the details in
* ArrayList
* */
public ArrayList<HashMap<String, String>> getPlayList() {
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);
try {
// Getting Array of Contacts
songslist = json.getJSONArray(TAG_str_song);
// looping through All Contacts
for (int i = 0; i < songslist.length(); i++) {
JSONObject c = songslist.getJSONObject(i);
// Storing each json item in variable
String str_song_name = c.getString(TAG_str_song_name);
String str_song_path = c.getString(TAG_str_song_path);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put("songTitle", (i+1) +". " + str_song_name);
map.put("songPath", "http://domain.com/" + str_song_path);
// adding HashList to ArrayList
songsList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
return songsList;
}
/**
* Class to filter files which are having .mp3 extension
* */
class FileExtensionFilter implements FilenameFilter {
public boolean accept(File dir, String name) {
return (name.endsWith(".mp3") || name.endsWith(".MP3"));
}
}
}
package com.name.musicplayer;
导入java.io.File;
导入java.io.FilenameFilter;
导入java.util.ArrayList;
导入java.util.HashMap;
导入org.json.JSONArray;
导入org.json.JSONException;
导入org.json.JSONObject;
导入com.name.musicplayer.JSONParser;
公共类歌曲管理器{
//SD卡路径
private ArrayList songsList=new ArrayList();
//发出请求的url
专用静态字符串url=”http://domain.com/android/songlist.php";
//JSON节点名称
私有静态最终字符串标记\u str\u song=“str\u song”;
私有静态最终字符串标记\u str\u song\u name=“str\u song\u name”;
私有静态最终字符串标记\u str\u song\u path=“str\u song\u path”;
//联系JSONArray
JSONArray songslist=null;
//建造师
公共歌曲管理器(){
}
/**
*从SD卡读取所有mp3文件并将详细信息存储在
*ArrayList
* */
公共阵列列表getPlayList(){
//创建JSON解析器实例
JSONParser jParser=新的JSONParser();
//从URL获取JSON字符串
JSONObject json=jParser.getJSONFromUrl(url);
试一试{
//获取联系人数组
songslist=json.getJSONArray(TAG_str_song);
//通过所有触点循环
for(int i=0;ivalue
地图放置(“songTitle”,(i+1)+“+str_song_名称);
地图放置(“songPath”http://domain.com/“+str_song_path);
//将哈希列表添加到ArrayList
歌曲列表。添加(地图);
}
}捕获(JSONException e){
e、 printStackTrace();
}
返回歌曲列表;
}
/**
*类来筛选扩展名为.mp3的文件
* */
类FileExtensionFilter实现FilenameFilter{
公共布尔接受(文件目录,字符串名称){
return(name.endsWith(“.mp3”)| name.endsWith(“.mp3”);
}
}
}
在没有看到堆栈跟踪的情况下,我假设NullPointerException
c
PlayListActivity.this.adapter_l.getFilter().filter(arg0);
adapter_l = new SimpleAdapter(this, songsListData,
R.layout.playlist_item, new String[] { "songTitle" }, new int[] {
R.id.songTitle });
setListAdapter(adapter_l);