Android - startActivityForResult 传回对象的 ArrayList

Question

So I have Activity A and Activity B, in "A" i need to go to "B" and then add Food items to an arrayList of them and then pass this array list back to Activity A, how ever i am getting issues with my current set up

This is the Intent From A to B

Intent i = new Intent(OrderMain.this , OrderAdd.class);
startActivityForResult(i,1);

This is the Return intent From B to A

Intent returnIntent = new Intent();
Bundle b = new Bundle();
b.putSerializable("results", orderArray);
returnIntent.putExtras(b);
setResult(Activity.RESULT_OK, returnIntent);
finish();

And finally this is my onActivityResults In A

    @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == 1) {
        if(resultCode == Activity.RESULT_OK){
            Bundle b = getIntent().getExtras();
            ArrayList<Food> test = new ArrayList<>();
            test = (ArrayList<Food>) b.getSerializable("results");
            setOrderArray(test);
        }
        if (resultCode == Activity.RESULT_CANCELED) {
            //Write your code if there's no result
        }
    }
}

setOrderArray is just a function to set the Array to the new returned Array

And this is the Food Object

import java.io.Serializable;

public class Food implements Serializable{
    private String name;
    private int cost;
    private int quantity;

public Food( String name, int cost, int quantity){
        this.name = name;
        this.cost = cost;
        this.quantity = quantity;
    }
    public void setQuantity(int quantity)
    {
        this.quantity = quantity;
    }
    public void setName(String name)
    {
       this.name = name;
    }
    public void setCost(int cost)
    {
        this.cost = cost;
    }
    public int getTotal()
    {
        return cost * quantity;
    }
    public String getName ()
    {
        return name;
    }
    public int getCost()
    {
        return cost;
    }
    public int getQuantity()
    {
        return quantity;
    }
    public void addQuantity()
    {
        quantity++;
    }
    public void decQuantity()
    {
        quantity--;
    }
}

the current issue i have is at this line of code:

test = (ArrayList<Food>) b.getSerializable("results");

It is saying there is an "Unchecked Cast" and the intended use for this does not work as it should, any help would be appreciated

Answer 1

Because you are getting data from wrong intent. You should change your code from

Bundle b = getIntent().getExtras();
ArrayList<Food> test = new ArrayList<>();
test = (ArrayList<Food>) b.getSerializable("results");

to

ArrayList<Food> test = (ArrayList<Food>) data.getSerializableExtra("results");

Answer 2

Do not use Serializable, use Parcelable instead. Parcelable is speed king and make sure your object class implements Parcelable.