Android ArrayList文件序列化

最近我读了上千篇关于android文件序列化的主题，但我仍然没有找到有效的解决方案

我有我的可序列化类和活动，其中我分别在

onResume（）

和

onPause（）

中使用可序列化类元素序列化和反序列化

ArrayList

我的解决方案仍然在seriazlie和反序列化方法中抛出IOException

package classes;

import java.io.Serializable;
import java.util.Date;

import com.google.android.maps.GeoPoint;

public class Note implements Serializable {

    public Note() {
    }

    public Note(Date date, String name, GeoPoint geoPoint) {
        this.date = date;
        this.name = name;
        this.geoPoint = geoPoint;
    }

    private static final long serialVersionUID = -7789719052842264659L;

    private Date date;
    private String name;
    private GeoPoint geoPoint;

    public Date getDate() {
        return date;
    }

    public String getName() {
        return name;
    }

    public GeoPoint getGeoPoint() {
        return geoPoint;
    }

    @Override
    public String toString() {
        return String.format("Name: %S%nDate: %2$td-%2$tb-%2$tY%nTime: %2$tH:%2$tM:%2$tS", name, date);
    }
}

以下是我的方法：

private void serializeQuotes() {
    try {
        FileOutputStream fos = openFileOutput("test.txt", Context.MODE_WORLD_READABLE);
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(notes);
        oos.close();
    }
    catch (IOException e) {
        Toast.makeText(this, "Serialization error", Toast.LENGTH_SHORT).show();
    }
}

@SuppressWarnings("unchecked")
private void deserializeQuotes() {
    try {
        FileInputStream fis = openFileInput("test.txt");
        ObjectInputStream ois = new ObjectInputStream(fis);
        notes = (ArrayList<Note>) ois.readObject();
        ois.close();
    }
    catch (IOException e) {
        Toast.makeText(this, "Deserialization error", Toast.LENGTH_SHORT).show();
    }
    catch (ClassNotFoundException e) {
    }
}

我需要在AppFolder中创建文件：

    File savedLocationsDirectory = new File(Environment.getExternalStorageDirectory().getPath().concat("/AppFolder"));
    if (!savedLocationsDirectory.exists()) savedLocationsDirectory.mkdirs();
    savedLocationsFile = new File(savedLocationsDirectory, "savedLocations.gc");

然后我使用：

FileInputStream fis=newfileinputstream（savedLocationsFile）

和

FileOutputStream fos=新的FileOutputStream（savedLocationsFile，true）

在这两种情况下，序列化都不起作用。
地质点不可序列化。例外追踪。哦，太简单了！谢谢
    File savedLocationsDirectory = new File(Environment.getExternalStorageDirectory().getPath().concat("/AppFolder"));
    if (!savedLocationsDirectory.exists()) savedLocationsDirectory.mkdirs();
    savedLocationsFile = new File(savedLocationsDirectory, "savedLocations.gc");