我如何可以排序的ArrayList我按字母顺序排列 [英] How can i sort my arraylist alphabetical
问题描述
我想我的排序按字母顺序排列的ArrayList,但我不明白这一点...也许你能帮助我。我不知道为什么,但我不能与collections.sort工作...我是什么编码错了吗?
非常感谢您的帮助和时间,Vinzenz
公共类SongsManager { 最后弦乐MEDIA_PATH = Environment.getExternalStorageDirectory()
.getPath()+/;
私人的ArrayList<&HashMap的LT;字符串,字符串>> songsList =新的ArrayList<&HashMap的LT;字符串,字符串>>();
私人字符串mp3Pattern =.MP3
私人字符串mp4Pattern =.MP4
私人字符串MP3Pattern =.MP3
私人字符串MP4Pattern =.MP4
私人字符串m4aPattern =名为.m4a; //构造
公共SongsManager(){ } / **
*功能读取所有MP3文件,并存储在细节
* ArrayList的
* * /
公众的ArrayList<&HashMap的LT;字符串,字符串>> getPlayList(){
的System.out.println(MEDIA_PATH);
如果(MEDIA_PATH!= NULL){
文件首页=新的文件(MEDIA_PATH);
文件[] listFiles = home.listFiles();
如果(listFiles =空&放大器;!&放大器; listFiles.length大于0){
对于(文件文件:listFiles){
的System.out.println(file.getAbsolutePath());
如果(file.isDirectory()){
scanDirectory(文件);
}其他{
addSongToList(文件);
}
}
} }
//返回歌曲列表数组
返回songsList; } 私人无效scanDirectory(文件目录){
如果(目录!= NULL){
文件[] listFiles = directory.listFiles();
如果(listFiles =空&放大器;!&放大器; listFiles.length大于0){
对于(文件文件:listFiles){
如果(file.isDirectory()){
scanDirectory(文件);
}其他{
addSongToList(文件); } }
}
}
} 私人无效addSongToList(文件歌曲){
如果(song.getName()的endsWith(mp3Pattern)|| song.getName()的endsWith(mp4Pattern)|| song.getName()的endsWith(MP4Pattern)|| song.getName()的endsWith(MP3Pattern)|| song.getName()。的endsWith(m4aPattern)){
HashMap的<字符串,字符串> songMap =新的HashMap<字符串,字符串>();
songMap.put(SONGTITLE
。song.getName()子串(0,(song.getName()长度() - 4)));
songMap.put(songPath,song.getPath()); //添加每一首歌的SongList
songsList.add(songMap);
}
}
}
使用 Collections.sort
Collections.sort(listOfStrings,String.CASE_INSENSITIVE_ORDER);
详情请参阅以下内容:
<一个href=\"http://docs.oracle.com/javase/6/docs/api/java/util/Collections.html#sort%28java.util.List,%20java.util.Comparator%29\"相对=nofollow> Collections.sort
您还可以创建自定义比较,而不是使用 String.CASE_INSENSITIVE_ORDER
I want to sort my arraylist alphabetical but I don't get it...maybe you can help me. I dont know why but i cant work with collections.sort...what am i coding wrong? thanks a lot for all your help and time, Vinzenz
public class SongsManager {
final String MEDIA_PATH = Environment.getExternalStorageDirectory()
.getPath() + "/";
private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
private String mp3Pattern = ".mp3";
private String mp4Pattern = ".mp4";
private String MP3Pattern = ".MP3";
private String MP4Pattern = ".MP4";
private String m4aPattern = ".m4a";
// Constructor
public SongsManager() {
}
/**
* Function to read all mp3 files and store the details in
* ArrayList
* */
public ArrayList<HashMap<String, String>> getPlayList() {
System.out.println(MEDIA_PATH);
if (MEDIA_PATH != null) {
File home = new File(MEDIA_PATH);
File[] listFiles = home.listFiles();
if (listFiles != null && listFiles.length > 0) {
for (File file : listFiles) {
System.out.println(file.getAbsolutePath());
if (file.isDirectory()) {
scanDirectory(file);
} else {
addSongToList(file);
}
}
}
}
// return songs list array
return songsList;
}
private void scanDirectory(File directory) {
if (directory != null) {
File[] listFiles = directory.listFiles();
if (listFiles != null && listFiles.length > 0) {
for (File file : listFiles) {
if (file.isDirectory()) {
scanDirectory(file);
} else {
addSongToList(file);
}
}
}
}
}
private void addSongToList(File song) {
if (song.getName().endsWith(mp3Pattern) || song.getName().endsWith(mp4Pattern) || song.getName().endsWith(MP4Pattern) || song.getName().endsWith(MP3Pattern) || song.getName().endsWith(m4aPattern)) {
HashMap<String, String> songMap = new HashMap<String, String>();
songMap.put("songTitle",
song.getName().substring(0, (song.getName().length() - 4)));
songMap.put("songPath", song.getPath());
// Adding each song to SongList
songsList.add(songMap);
}
}
}
Use Collections.sort
Collections.sort(listOfStrings, String.CASE_INSENSITIVE_ORDER);
See the following for details:
You can also create a custom Comparator, instead of using String.CASE_INSENSITIVE_ORDER
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