java - Android ListView 不会填充 SQLite DB 中的所有条目

Question

我正在开发一个学习 Android 应用程序(我称之为 PersistAlarm)，我可以在其中设置闹钟。应用程序的第一个 Activity 是一个带有 ListView 的按钮，用户可以在其中向应用程序添加警报。警报在第二个 Activity 中设置，并填充后端的数据库。

设置警报后，它将返回到填充警报列表的第一个 Activity (PersistAlarm.java)。

问题是，到目前为止，我能够获取警报列表。突然间，现在只有警报表中的第一个条目可见。其他条目不显示。奇怪!

谁能告诉我哪里出错了？

这是 PersistAlarm Activity XML

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".PersistAlarm" >

<Button
    android:id="@+id/buttonAddAlarm"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Add Entry" />

<ListView
    android:id="@+id/alarmListV"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >
</ListView>

这是 PersistAlarm.java 代码

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_persist_alarm);

    final AlarmAdapter alarmAdapt;
    final ListView mainAlarmView;

    final Context context = this;



    Button alarmAdd = (Button) findViewById(R.id.buttonAddAlarm);

    mainAlarmView = (ListView) findViewById(R.id.alarmListV);

    alarmAdd.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            Intent intent = new Intent(context, AddEditAlarm.class);
            startActivity(intent);
        }
    });

    List<PAlarm> alarmList = db.getAllAlarms();
    Log.d("LIST COUNT" , String.valueOf(alarmList.size()));
    alarmAdapt = new AlarmAdapter(PersistAlarm.this, R.id.alarmListV, alarmList);
    mainAlarmView.setAdapter(alarmAdapt);

}

这是我的 PAlarm 对象，它充当应用程序的基础对象:

public class PAlarm {

int _id;
String _eventName;
String _eventDate;
String _eventTime;
String _type;

public PAlarm() {

}

public PAlarm(int id, String eventName, String eventDate, String eventTime, String type) {
    this._id = id;
    this._eventName = eventName;
    this._eventDate = eventDate;
    this._eventTime = eventTime;
    this._type = type;
}

public PAlarm(String eventName, String eventDate, String eventTime, String type) {
    this._eventName = eventName;
    this._eventDate = eventDate;
    this._eventTime = eventTime;
    this._type = type;
}

public int get_id() {
    return _id;
}

public void set_id(int _id) {
    this._id = _id;
}

public String get_eventName() {
    return _eventName;
}

public void set_eventName(String _eventName) {
    this._eventName = _eventName;
}

public String get_eventDate() {
    return _eventDate;
}

public void set_eventDate(String _eventDate) {
    this._eventDate = _eventDate;
}

public String get_eventTime() {
    return _eventTime;
}

public void set_eventTime(String _eventTime) {
    this._eventTime = _eventTime;
}

public String get_type() {
    return _type;
}

public void set_type(String _type) {
    this._type = _type;
}

@Override
public String toString() {
    return this._id + ". " + this._eventName + " - " + this._eventDate + " - " + this._eventTime; 
}

这是我用来渲染 ListView 的自定义适配器

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/alarmNameTV"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24dip" />
    <TextView
        android:id="@+id/alarmDateTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="9dip" />

</LinearLayout>

另外，我的自定义适配器的 java 代码:

public class AlarmAdapter extends ArrayAdapter<PAlarm> {
private List<PAlarm> alarms;
private Activity activity;

public AlarmAdapter(Activity a, int textViewId, List<PAlarm> alms) {
    super(a, textViewId, alms);
    this.alarms = alms;
    this.activity = a;

}

public static class ViewHolder {
    public TextView alarmView;
    public TextView alarmDateTimeView;

}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    View v = convertView;
    ViewHolder holder;

    if (v == null) {
        LayoutInflater vi = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = vi.inflate(R.layout.alarm_item, null);
        holder = new ViewHolder();
        holder.alarmView = (TextView) v.findViewById(R.id.alarmNameTV);
        holder.alarmDateTimeView = (TextView) v.findViewById(R.id.alarmDateTime);
        v.setTag(holder);
    } else {
        holder = (ViewHolder) v.getTag();
        final PAlarm alarm  = alarms.get(position);
        if (alarm != null) {
            holder.alarmView.setText(alarm.get_eventName());
            holder.alarmDateTimeView.setText(alarm.get_eventDate() + " (" + alarm.get_eventTime() + ")" );
        }   
    }

    return v;

}

希望得到一些帮助。谢谢

Answer 1

尝试更改您的getView():

public View getView(int position, View convertView, ViewGroup parent) {

    View v = convertView;
    ViewHolder holder;

    if (v == null) {
        LayoutInflater vi = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = vi.inflate(R.layout.alarm_item, null);
        holder = new ViewHolder();
        holder.alarmView = (TextView) v.findViewById(R.id.alarmNameTV);
        holder.alarmDateTimeView = (TextView) v.findViewById(R.id.alarmDateTime);
        v.setTag(holder);
    } else {
        holder = (ViewHolder) v.getTag();


        }   
   final PAlarm alarm  = alarms.get(position);
   if (alarm != null) {
       holder.alarmView.setText(alarm.get_eventName());
       holder.alarmDateTimeView.setText(alarm.get_eventDate() + " (" + alarm.get_eventTime() + ")" );
    }

    return v;

}

说明:

在 ListView 中，如果 getView() 中的 view 为 null，则 View 将被回收，这意味着 view 没有被回收，我们必须初始化它；我们在 if 条件下执行的操作。如果view不为null，则意味着它被回收，我们只需更改该view的数据即可。

所以 View 是否被回收我们必须设置数据。所以数据设置代码应该在 if...else

之外