我有三个模型如下:
坐标模型
public class Coordinate implements Parcelable{
private static final long serialVersionUID = 1L;
private double latitude,longitude;
private double x,y;
private double bearing,distance;
protected Coordinate(Parcel in) {
latitude = in.readDouble();
longitude = in.readDouble();
x = in.readDouble();
y = in.readDouble();
bearing = in.readDouble();
distance = in.readDouble();
}
public static final Creator<Coordinate> CREATOR = new Creator<Coordinate>() {
@Override
public Coordinate createFromParcel(Parcel in) {
return new Coordinate(in);
}
@Override
public Coordinate[] newArray(int size) {
return new Coordinate[size];
}
};
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeDouble(latitude);
dest.writeDouble(longitude);
dest.writeDouble(x);
dest.writeDouble(y);
dest.writeDouble(bearing);
dest.writeDouble(distance);
}
public Coordinate(double lat,double lng,double x,double y,double distance,double bearing){
this.latitude=lat;
this.longitude=lng;
this.x=x;
this.y=y;
this.distance=distance;
this.bearing=bearing;
}
private Coordinate() {
// TODO Auto-generated constructor stub
}
public double getBearing() {
return bearing;
}
public double getDistance() {
return distance;
}
public double getLatitude() {
return latitude;
}
public double getX() {
return x;
}
public double getY() {
return y;
}
public double getLongitude() {
return longitude;
}
public void setLatitude(double latitude) {
this.latitude = latitude;
}
public void setLongitude(double longitude) {
this.longitude = longitude;
}
public void setX(double x) {
this.x = x;
}
public void setY(double y) {
this.y = y;
}
public void setBearing(double bearing) {
this.bearing = bearing;
}
public void setDistance(double distance) {
this.distance = distance;
}
}
使用坐标的区域模型
public class Area implements Parcelable{
private static final long serialVersionUID = 1L;
private List<Coordinate> coordinates;
private static Double R=63710000.0;
protected Area(Parcel in) {
coordinates = new ArrayList<Coordinate>();
in.readTypedList(coordinates,Coordinate.CREATOR);
}
public static final Creator<Area> CREATOR = new Creator<Area>() {
@Override
public Area createFromParcel(Parcel in) {
return new Area(in);
}
@Override
public Area[] newArray(int size) {
return new Area[size];
}
};
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeTypedList(coordinates);
}
private Area() {
}
public Area(List<Coordinate> coordinates) {
this.coordinates = coordinates;
}
public Area(LatLng origin){
coordinates=new ArrayList<Coordinate>();
coordinates.add(new Coordinate(origin.latitude,origin.longitude,0,0,0,0));
}
public double getArea(){
double ar=0,x1=0,y1=0,x2=0,y2=0;
if(coordinates.size()>2) {
for (int i = 1; i < coordinates.size(); i++) {
x1 = coordinates.get(i).getX();
y1 = coordinates.get(i).getY();
x2 = coordinates.get(i - 1).getX();
y2 = coordinates.get(i - 1).getY();
ar += x1 * y2 - x2 * y1;
}
ar+=x1 *coordinates.get(0).getY()-y1*coordinates.get(0).getX();
ar=Math.abs(ar)/2;
}
return ar;
}
public List<Coordinate> getCoordinates() {
return coordinates;
}
public void addLatLng(LatLng latLng){
double bearing =this.getBearing(latLng);
double distance=this.getDistance(latLng);
double y=distance*Math.cos(bearing);
double x=distance*Math.sin(bearing);
coordinates.add(new Coordinate(latLng.latitude,latLng.longitude,x,y,distance,bearing));
}
public boolean removeLatLan(){
//returns true if Coordinate is removed and false if only last coordinate is left
//does not remove the last coordinate
if(coordinates.size()<=1){
return false;
}
coordinates.remove(coordinates.size()-1);
return true;
}
public List<LatLng> getLatLngList(){
List<LatLng> res=new ArrayList<LatLng>(coordinates.size());
for(Coordinate c:coordinates){
LatLng l=new LatLng(c.getLatitude(),c.getLongitude());
res.add(l);
}
return res;
}
private double getDistance(LatLng latLng){
Coordinate origin=coordinates.get(0);
double ph1=origin.getLatitude()*Math.PI/180;
double ph2=latLng.latitude*Math.PI/180;
double delTa=(latLng.longitude-origin.getLongitude())*Math.PI/180;
double distance=R*Math.acos(Math.sin(ph1)*Math.sin(ph2)+
Math.cos(ph1)*Math.cos(ph2)*Math.cos(delTa));
return distance;
}
private double getBearing(LatLng latLng){
Coordinate origin=coordinates.get(0);
double ph1=origin.getLatitude()*Math.PI/180;
double ph2=latLng.latitude*Math.PI/180;
double delTa=(latLng.longitude-origin.getLongitude())*Math.PI/180;
double y= Math.sin(delTa)*Math.cos(ph2);
double x= Math.cos(ph1)*Math.sin(ph2)-Math.sin(ph1)*Math.cos(ph2)*Math.cos(delTa);
return Math.atan2(y,x);
}
public void setCoordinates(List<Coordinate> coordinates) {
this.coordinates = coordinates;
}
}
然后来农场模型
public class Farm implements Parcelable{
private static final long serialVersionUID = 1L;
Long id;
String webSafeKey;
Float productivity;
String address;
ArrayList<Area> areas;
public Farm(Context context, com.appspot.myapi.snapapi.model.Farm farm){
this.id = farm.getId();
webSafeKey = farm.getWebSafeKey();
productivity = 0f;
address = farm.getAddress()==null?context.getResources().getString
(R.string.address)
+": "+context.getResources().getString(R.string.NA):farm.getAddress();
areas = new ArrayList<Area>();
for(com.appspot.myapi.snapapi.model.Area areas: farm.getAreas()){
List<LatLng> list = areas.getLatLngList();
Area area = new Area(new com.google.android.gms.maps.model.LatLng(
list.get(0).getLatitude(),list.get(0).getLongitude()
));
for(int i=1;i<list.size();i++){
area.addLatLng(new com.google.android.gms.maps.model.LatLng(
list.get(i).getLatitude(),list.get(i).getLongitude()
));
}
this.areas.add(area);
}
}
protected Farm(Parcel in) {
if (in.readByte() == 0) {
id = null;
} else {
id = in.readLong();
}
webSafeKey = in.readString();
productivity = in.readFloat();
address = in.readString();
areas = new ArrayList<Area>();
in.readTypedList(areas,Area.CREATOR);
// areas = in.readArrayList(null);
}
public static final Creator<Farm> CREATOR = new Creator<Farm>() {
@Override
public Farm createFromParcel(Parcel in) {
return new Farm(in);
}
@Override
public Farm[] newArray(int size) {
return new Farm[size];
}
};
@Override
public int describeContents() {
return 0;
}
public void writeToParcel(Parcel out, int flags) {
out.writeLong(id);
out.writeString(webSafeKey);
out.writeFloat(productivity);
out.writeString(address);
out.writeTypedList(areas);
}
public Double getTotalArea(){
double totalArea=0d;
for(Area area:areas){
totalArea +=area.getArea();
}
return totalArea;
}
public Long getId() {
return id;
}
public String getWebSafeKey() {
return webSafeKey;
}
public float getProductivity() {
return productivity;
}
public String getAddress() {
return address;
}
public ArrayList<Area> getAreas() {
return areas;
}
public void setId(Long id) {
this.id = id;
}
public void setWebSafeKey(String webSafeKey) {
this.webSafeKey = webSafeKey;
}
public void setProductivity(Float productivity) {
this.productivity = productivity;
}
public void setAddress(String address) {
this.address = address;
}
public void setAreas(ArrayList<Area> areas) {
this.areas = areas;
}
}
现在的问题是,当我将Farm
类作为额外内容传递给Intent并尝试在第二个Activity中读取它时,in.readTypedList(areas, Area.CREATOR)
给出了OutOfMemoryError
。准确地说,这是完整的堆栈跟踪:
java.lang.OutOfMemoryError: Failed to allocate a 30536292 byte allocation with 16041952 free bytes and 15MB until OOM
at java.util.ArrayList.add(ArrayList.java:118)
at android.os.Parcel.readTypedList(Parcel.java:2043)
at in.agrosnap.android.helper.Farm.<init>(Farm.java:60)
at in.agrosnap.android.helper.Farm$1.createFromParcel(Farm.java:67)
at in.agrosnap.android.helper.Farm$1.createFromParcel(Farm.java:64)
at android.os.Parcel.readParcelable(Parcel.java:2367)
at android.os.Parcel.readValue(Parcel.java:2264)
at android.os.Parcel.readArrayMapInternal(Parcel.java:2614)
at android.os.BaseBundle.unparcel(BaseBundle.java:221)
at android.os.Bundle.getParcelable(Bundle.java:786)
at android.content.Intent.getParcelableExtra(Intent.java:5387)
at in.agrosnap.android.FarmDetail.onCreate(FarmDetail.java:79)
at android.app.Activity.performCreate(Activity.java:6259)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1130)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2490)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1354)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
有人可以解释我在哪里出错了,编组和解组用户定义类的实现是错误的吗?
我使用以下引用来编写此代码:
答案 0 :(得分:1)
在Farm
课程中,您有以下两种匹配方法:
protected Farm(Parcel in) { if (in.readByte() == 0) { id = null; } else { id = in.readLong(); } webSafeKey = in.readString(); productivity = in.readFloat(); address = in.readString(); areas = new ArrayList<Area>(); in.readTypedList(areas,Area.CREATOR); //areas = in.readArrayList(null); }
public void writeToParcel(Parcel out, int flags) { out.writeLong(id); out.writeString(webSafeKey); out.writeFloat(productivity); out.writeString(address); out.writeTypedList(areas); }
构造函数调用in.readByte()
,但从未在writeToParcel()
方法中编写。您的writeToParcel()
看起来应如下所示:
public void writeToParcel(Parcel out, int flags) {
if (id != null) {
out.writeByte((byte) 1);
out.writeLong(id);
} else {
out.writeByte((byte) 0);
}
out.writeString(webSafeKey);
out.writeFloat(productivity);
out.writeString(address);
out.writeTypedList(areas);
}
这显然不会导致OutOfMemoryError
,但是,在尝试读取列表的大小并获取大量数据之前,可能会使分区数据“排列”得足够好,因为读取/写入是错位的。