I am working on a project that involves me having to share an array list of objects with all of the activities that make up the application. Until recently I was passing the list between activities by implementing the parcelable interface. An example of this is seen below:
MenuItem class:
ublic class MenuItem implements Parcelable {
private String name;
private double price;
private int qty;
private String info;
public MenuItem(String name, double price) {
super();
this.name = name;
this.price = price;
}
public MenuItem() {
// TODO Auto-generated constructor stub
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public int getQty() {
return qty;
}
public void setQty(int qty) {
this.qty = qty;
}
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
@Override
public String toString() {
return name;
}
//Parcelable methods.
public static final Parcelable.Creator<MenuItem> CREATOR = new Parcelable.Creator<MenuItem>() {
@Override
public MenuItem createFromParcel(Parcel source) {
return new MenuItem(source);
}
@Override
public MenuItem[] newArray(int size) {
return new MenuItem[size];
}
};
public MenuItem(Parcel source) {
this();
readFromParcel(source);
}
private void readFromParcel(Parcel source) {
name = source.readString();
price = source.readDouble();
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(name);
dest.writeDouble(price);
}
}
Order class - which I would change to be the Singleton (holds list of menu items)
public class Order implements Parcelable {
private int covers;
private int table;
private ArrayList<MenuItem> items;
public Order(){
super();
this.items = new ArrayList<MenuItem>();
}
public static final Parcelable.Creator<Order> CREATOR = new Parcelable.Creator<Order>() {
@Override
public Order createFromParcel(Parcel source) {
return new Order(source);
}
@Override
public Order[] newArray(int size) {
return new Order[size];
}
};
public Order(int covers, int table) {
super();
this.covers = covers;
this.table = table;
this.items = new ArrayList<MenuItem>();
}
public int getCovers() {
return covers;
}
public void setCovers(int covers) {
this.covers = covers;
}
public int getTable() {
return table;
}
public void setTable(int table) {
this.table = table;
}
public ArrayList<MenuItem> getItems() {
return items;
}
public void setItems(ArrayList<MenuItem> items) {
this.items = items;
}
//add to order
public void addToOrder(MenuItem m){
items.add(m);
}
//remove from order
public void removeFromOrder(MenuItem m){
items.remove(m);
}
public Order(Parcel source) {
this();
readFromParcel(source);
}
@Override
public int describeContents() {
// TODO Auto-generated method stub
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
// TODO Auto-generated method stub
dest.writeInt(covers);
dest.writeInt(table);
dest.writeTypedList(items);
}
private void readFromParcel(Parcel source) {
// TODO Auto-generated method stub
covers = source.readInt();
table = source.readInt();
items = new ArrayList<MenuItem>();
source.readTypedList(items, MenuItem.CREATOR);
}
}
This is how I pass the data between activities:
myOrderBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(v.getContext(), "myOrderBtn", Toast.LENGTH_SHORT).show();
Intent i = new Intent(v.getContext(), ViewOrderActivity.class);
i.putExtra("data", order);
if(!saved){
saveOrderState();
}
startActivity(i);
}
});
and retrieve this way:
public void getOrderData(){
Intent i = getIntent();
if(i != null && i.hasExtra("data")){
order = i.getParcelableExtra("data");
Toast.makeText(this.getApplicationContext(), "STARTERS recieved order object, covers: " + order.getCovers() + " table no: " + order.getTable() + " order size: " + order.getItems().size(), Toast.LENGTH_SHORT).show();
if(order.getItems().size() == 0){
//Toast.makeText(this.getApplicationContext(), "No items added to your order...", Toast.LENGTH_SHORT).show();
}else{
for(int j = 0; j != order.getItems().size(); j++){
dishItems.add(order.getItems().get(j));
}
}
saved = false;
}
}
Today I learned about the use of a Singleton for global access to data, and I am wondering would it be a good idea to switch to this style of data access? It seems easier to control and a lot tidier with respects to the code.
I'd be interested to see what your opinions on this are. This link here is the pattern I would like to implement:
I should mention, the project is part of my studies in my course. I have to submit my code in a few weeks time, so I am looking for the best way to make it more efficient. So please let me know if you see anything that looks wrong as well!
