将字符串与冒泡排序算法进行比较

Question

我有一个程序会从数据库中获取几个字符串（announcementId 和announcementTitle），

然后对于从数据库中获取的每个字符串，我想比较它们中的每一个（比较所有获取的announcementId），

如果字符串 (announcementId) 具有不同的值，那么它将使用announcementTitle 创建一个新按钮，因为它是从数据库中获取的（按钮）值。

我尝试学习如何，发现在这种情况下可以使用冒泡排序算法，但是程序中存在一些错误..索引超出范围异常.. 然后我尝试了一些代码并尝试更改数组，但它仍然不起作用。

能否请您看一下我的代码并告诉我错误在哪里以及修复错误的最佳方法

这是我的代码：

    myDb = new Database(ViewAllAnnouncement.this);
    myDb.open();
    totalAnnouncement = myDb.countHowManyAnnouncement(username);
    String temp = Integer.toString(totalAnnouncement);
    //Toast.makeText(getApplicationContext(), temp, Toast.LENGTH_LONG).show();

    String[] announcementTitle = myDb.fetchMyAnnouncement(username);
    String[] announcementId = myDb.fetchAnnouncementId(username);

    for (int i = 0; i < totalAnnouncement; i++) {

        for (int j = 0; j < totalAnnouncement - i; j++) {
            if (j > 0 || j < totalAnnouncement-i) {
                if (!announcementId[j].equals(announcementId[i])) {

                    newBt = new Button(this);
                    newBt.setTag(announcementId[i]);
                    newBt.setText(announcementTitle[i]);
                    newBt.setOnClickListener(new View.OnClickListener() {

                        @Override
                        public void onClick(View v) {
                            // TODO Auto-generated method stub
                            Button mButt = (Button) v;
                            String temp = (String) mButt.getTag();
                            Intent intent = new Intent(
                                    "com.example.teamizer.VIEWCHILDANNOUNCEMENT");
                            intent.putExtra("annId", temp);
                            startActivity(intent);
                        }
                    });
                    layout.addView(newBt);
                }
            }
        }
    }

    myDb.close();

这是我返回announcementId的方法

    public String[] fetchAnnouncementId(String Username) {
    // TODO Auto-generated method stub
    int i = 0;

    String Query = "SELECT b." + ANNOUNCEMENT_ID + " FROM "
            + MS_GROUP_DETAIL + " a, " + MS_ANNOUNCEMENT_DETAIL + " b, "
            + MS_ANNOUNCEMENT + " c WHERE a." + GROUP_ID + " = b."
            + GROUP_ID + " AND b. " + ANNOUNCEMENT_ID + " = c."
            + ANNOUNCEMENT_ID + " AND a." + MEMBER_USERNAME + " =? ORDER BY b." +ANNOUNCEMENT_ID;
    Cursor c = ourDatabase.rawQuery(Query, new String[] { Username });

    String temp[] = new String[c.getCount()];
    int iArray = c.getColumnIndex(ANNOUNCEMENT_ID);

    c.moveToFirst();
    for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
        temp[i] = c.getString(iArray);
        i++;
    }
    c.close();
    return temp;
}

Answer 1

如果 冒泡排序 是答案，那么你一定误解了这个问题。我强烈建议您添加

ORDER BY announcementId

到您的查询结束。这样，数据库将为您按列排序。

编辑 你可以使用

ORDER BY 1

按第一列排序（并省略名称）。然后，您的代码应该类似于

for (int i = 0; i < totalAnnouncement - 1;) {
    int j = i + 1;
    for (; j < totalAnnouncement; j++) {
        if (!announcementId[j].equals(announcementId[i])) {
            break;
        }
    }
    // j is the first value where the announcementId changes
    newBt = new Button(this);
    newBt.setTag(announcementId[i]);
    newBt.setText(announcementTitle[i]);
    newBt.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Button mButt = (Button) v;
            String temp = (String) mButt.getTag();
            Intent intent = new Intent(
                    "com.example.teamizer.VIEWCHILDANNOUNCEMENT");
            intent.putExtra("annId", temp);
            startActivity(intent);
        }
    });
    layout.addView(newBt);
    i = j; // <-- assign j to i.
}