首页 > 代码库 > Android 利用cursor来进行排序（转至http://blog.csdn.net/yangzongquan/article/details/6547860）

Android 利用cursor来进行排序（转至http://blog.csdn.net/yangzongquan/article/details/6547860）

2024-07-05 18:48:49   224人阅读

主要思路是:override move系列的方法,让cursor以自己想要的顺序来移动,从而达到对cursor排序的目的。比如数组A0里有 4(0),3(1),1(2),2(3),括号内为位置,排序后用数据记录A1:1(2),2(3),3(1),4(0)。要访问第一个元素,则访问 A1[0]得到1(2),根据(2)找到在A0中的实际位置2,即1(2)。参考了下系统的CursorWrapper和AbstractCursor代 码实现,另外有时间可以顺带了解下MatrixCursor。

 

package com.xx.test;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import android.database.Cursor;
import android.database.CursorWrapper;
import com.xx.test.SortCursor.SortEntry;
public class SortCursor extends CursorWrapper implements Comparator<SortEntry>{
    
    public SortCursor(Cursor cursor) {
        super(cursor);
    }
    
    Cursor mCursor;
    ArrayList<SortEntry> sortList = new ArrayList<SortEntry>();
    int mPos = 0;
    public static class SortEntry {
        public String key;
        public int order;
    }

    public int compare(SortEntry entry1, SortEntry entry2) {
        return entry1.key.compareTo(entry2.key);
    }
    
    public SortCursor(Cursor cursor, String columnName) {
        super(cursor);
        
        mCursor = cursor;
        if (mCursor != null && mCursor.getCount() > 0) {
            int i = 0;
            int column = cursor.getColumnIndexOrThrow(columnName);
            for (mCursor.moveToFirst(); !mCursor.isAfterLast(); mCursor.moveToNext(), i++) {
                SortEntry sortKey = new SortEntry();
                sortKey.key = cursor.getString(column);
                sortKey.order = i;
                sortList.add(sortKey);
            }
        }
        Collections.sort(sortList, this);
    }
    public boolean moveToPosition(int position) {
        if (position >= 0 && position < sortList.size()) {
            mPos = position;
            int order = sortList.get(position).order;
            return mCursor.moveToPosition(order);
        }
        if (position < 0) {
            mPos = -1;
        }
        if (position >= sortList.size()) {
            mPos = sortList.size();
        }
        return mCursor.moveToPosition(position);
    }
    public boolean moveToFirst() {
        return moveToPosition(0);
    }
    public boolean moveToLast() {
        return moveToPosition(getCount() - 1);
    }
    public boolean moveToNext() {
        return moveToPosition(mPos + 1);
    }
    public boolean moveToPrevious() {
        return moveToPosition(mPos - 1);
    }
    public boolean move(int offset) {
        return moveToPosition(mPos + offset);
    }
    public int getPosition() {
        return mPos;
    }
}

 

 

 


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