java - 在Android中使用Gson读取自定义类的ArrayList

Question

尝试从文件加载用户行程列表以携带用户的运行总计。

这是我从中读取它的对象，以及 UserTrip 的类文件

         public static ArrayList<UserTrip> tripList = new ArrayList<UserTrip>();

          StringBuilder stringBuilder = null;
    try {
        FileInputStream inputStream = openFileInput("ridefile.txt");
        InputStreamReader isr = new InputStreamReader(inputStream);
        BufferedReader bufferedReader = new BufferedReader(isr);
        stringBuilder = new StringBuilder();
        String line;
        while ((line = bufferedReader.readLine()) != null) {
            stringBuilder.append(line);
        }

    } catch (IOException e) {
        e.printStackTrace();
    }
    String json = stringBuilder.toString();
    Gson gson = new Gson();

    MapsActivity.tripList = gson.fromJson(json,ArrayList.class);

公共(public)类UserTrip { 私有(private)日历pickupDate；//保存下车的日期和时间 私有(private)日历 dropoffDate；//保存下车日期和时间

private Location pickupLocation;
private Location dropoffLocation;

private LatLng pickupLatLng;
private LatLng dropoffLatLng;


private String pickupAddress; //holds readable pick address
private String dropoffAddress; //holds readable drop address

private double tripMileage; //holds trip mileage
private double traveltoMileage; //holds distance traveled empty to pickup



//track time and tripMileage to next trip


public UserTrip(){ //Constructor for individual user trips

}

public void setPickupDate(Calendar n){

    pickupDate = n;
}

public void setDropoffDate(Calendar n){

    dropoffDate = n;
}

public void setPickupLocation(Location n) {
    pickupLocation = n;
    setPickupLatLng(new LatLng(n.getLatitude(),n.getLongitude()));
}

public void setDropoffLocation(Location n) {
    dropoffLocation = n;
    setDropoffLatLng(new LatLng(n.getLatitude(),n.getLongitude()));
}

public void setPickupAddress(String n){
    pickupAddress = n;
}

public void setDropoffAddress(String n){
    dropoffAddress = n;
}

public void setTripMileage(double n){
    tripMileage = n;
}

public void setTraveltoMileage(double n) {
    traveltoMileage = n;
}

public void setPickupLatLng(LatLng pickupLatLng) {
    this.pickupLatLng = pickupLatLng;
}

public void setDropoffLatLng(LatLng dropoffLatLng) {
    this.dropoffLatLng = dropoffLatLng;
}

public Calendar getDropoffDate(){
    return(dropoffDate);
}

public Calendar getPickupDate(){
    return (pickupDate);
}

public String getPickupAddress(){
    return pickupAddress;
}

public String getDropoffAddress(){
    return dropoffAddress;
}

public double getTripMileage(){
    return tripMileage;
}

public Location getPickupLocation() {
    return pickupLocation;
}

public Location getDropoffLocation() {
    return dropoffLocation;
}

public double getTraveltoMileage() {
    return traveltoMileage;
}

public LatLng getDropoffLatLng() {
    return dropoffLatLng;
}

public LatLng getPickupLatLng() {
    return pickupLatLng;
}

}

Answer 1

我相信你想做的就是详细的here之类的事情

基本上，改变你的线路

MapsActivity.tripList = gson.fromJson(json,ArrayList.class);

至

MapsActivity.tripList = gson.fromJson(json,new TypeToken<ArrayList<UserTrip>>(){}.getType());