当记录 = 值时，如何检查 HashMap<String, String> 和 setBackgroundResource 中的值？答案

【问题标题】：How to check values in HashMap<String, String> and setBackgroundResource when record = value?当记录 = 值时，如何检查 HashMap<String, String> 和 setBackgroundResource 中的值？
【发布时间】：2016-05-25 22:22:37
【问题描述】：

我刚刚开始使用 Android Studio 2.1 编写一个 Android 应用程序，我的应用程序有点像离线消息传递 - 这是使用 SQLite 数据库（基本上由两个表消息和联系人组成）。

我现在正在进行最后一项活动，我需要从创建的联系人中填充消息交换列表。我能够列出它们，但没有美学。每当类型是 LEFT 或 RIGHT 但难以应用它时，我想设置不同的 setBackgroundResource 。以下是我的代码：

MessageRepo - SQLite DBhelper：

    public ArrayList<HashMap<String, String>> getMessageListById(int fromid, int toid) {
    SQLiteDatabase db = helper.getWritableDatabase();
    String toquery = "SELECT " + MessageModel.messageId +
            ", " + MessageModel.fromId +
            ", " + MessageModel.toId +
            ", " + MessageModel.messageContent +
            ", 'RIGHT' AS type FROM " + MessageModel.tableMessage +
            " WHERE " + MessageModel.toId +
            " = ? AND " + MessageModel.fromId +
            " = ? ";
    String fromquery = "SELECT " + MessageModel.messageId +
            ", " + MessageModel.fromId +
            ", " + MessageModel.toId +
            ", " + MessageModel.messageContent +
            ", 'LEFT' AS type FROM " + MessageModel.tableMessage +
            " WHERE " + MessageModel.fromId +
            " = ? AND " + MessageModel.toId +
            " = ? ";
    String query = toquery +
            " UNION " + fromquery +
            " ORDER BY " + MessageModel.messageId;

    ArrayList<HashMap<String, String>> messageList = new ArrayList<HashMap<String, String>>();

    Cursor cursor = db.rawQuery(query, new String[]{String.valueOf(fromid), String.valueOf(toid), String.valueOf(fromid), String.valueOf(toid)});
    if (cursor.moveToFirst()) {
        do {
            HashMap<String, String> messages = new HashMap<String, String>();
            messages.put("messageId", cursor.getString(0));
            messages.put("messageFromId", cursor.getString(1));
            messages.put("messageToId", cursor.getString(2));
            messages.put("messageContent", cursor.getString(3));
            messages.put("type", cursor.getString(4));
            messageList.add(messages);
        } while (cursor.moveToNext());
    }
    cursor.close();
    db.close();
    return messageList;
}

消息活动 - 这将显示在 ListView 中，但无法正常工作：

        ArrayList<HashMap<String, String>> messageList = messagehandler.getMessageListById(_fromid, _toid);
    if (messageList.size() != 0) {
        ListView listView = getListView();
        if(messageList.contains("RIGHT")) {
            listView.setBackgroundResource(R.drawable.right);
        } else {
            listView.setBackgroundResource(R.drawable.left);
        }

        ListAdapter adapter = new SimpleAdapter(MessageDetailActivity.this, messageList, R.layout.message, new String[]{"messageFromId", "messageToId", "messageContent"}, new int[]{R.id.FromId, R.id.ToId, R.id.message});
        setListAdapter(adapter);
        }

我检查了很多帖子，但似乎无法让它对我有用： The constructor ArrayAdapter>>(Context, int, ArrayList>) is undefined Android Alternate row Colors in ListView

提前非常感谢！

【问题讨论】：

标签： android listview arraylist hashmap android-studio-2.1

【解决方案1】：

经过更多研究。我终于通过选择使用 List 和 setter/getter 类找到了答案：

public class MessagesAdapter extends ArrayAdapter<ContactsAndMessages> {

public MessagesAdapter(Context context, List<ContactsAndMessages> contacts) {
    super(context, 0, contacts);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ContactsAndMessages contact = getItem(position);

    Typeface typeface = Typeface.createFromAsset(getContext().getAssets(), "fonts/helvetica.ttf");

    if(convertView == null) {
        if (contact.type.equalsIgnoreCase("me")) {....

【讨论】：