Android 如何正确执行托管查询？

我是根据API 11开发的，所以我认为没有必要使用

LoadCursor

我有三个类：

main活动扩展活动

，

Columns扩展PagerAdapter

，和

GetMp3Tag

main活动

miAdapter = new Columns ();
columnas = (ViewPager) findViewById(R.id.columnas);
columnas.setAdapter(miAdapter);

GetMP3Tag MP3TAG = new GetMP3Tag();
MP3TAG.GetCount(types_ID.ALL_ARTIST);

public String GetCount(types_ID Type_First) {
    Cursor cursor;
    cursor = managedQuery(Path_Normal, STAR , audioselection, null, null);
}

列

miAdapter = new Columns ();
columnas = (ViewPager) findViewById(R.id.columnas);
columnas.setAdapter(miAdapter);

GetMP3Tag MP3TAG = new GetMP3Tag();
MP3TAG.GetCount(types_ID.ALL_ARTIST);

public String GetCount(types_ID Type_First) {
    Cursor cursor;
    cursor = managedQuery(Path_Normal, STAR , audioselection, null, null);
}

GetMp3Tag

miAdapter = new Columns ();
columnas = (ViewPager) findViewById(R.id.columnas);
columnas.setAdapter(miAdapter);

GetMP3Tag MP3TAG = new GetMP3Tag();
MP3TAG.GetCount(types_ID.ALL_ARTIST);

public String GetCount(types_ID Type_First) {
    Cursor cursor;
    cursor = managedQuery(Path_Normal, STAR , audioselection, null, null);
}

LogCat

FATAL EXCEPTION: main
java.lang.NullPointerException at android.content.ContextWrapper.getContentResolver(ContextWrapper.java:99)

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使用getContentResolver（）.query代替managedQuery（..）。显示整个堆栈跟踪。使用getContentResolver（）.query我会得到相同的错误