java Java中的数组列表意图额外

Array List Intent extra in Java

提问by starrystar

I am trying to skip my ArrayListthrough Intent. But I cannot find what to write in extra? Any get methods I am getting errors like "not applicable for string."

我想我要跳过ArrayList通过Intent。但是我找不到额外写什么？任何获取方法都会出现“不适用于字符串”之类的错误。

Item Details:

项目详情：

public class ItemDetails {

public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getItemDescription() {
    return itemDescription;
}
public void setItemDescription(String itemDescription) {
    this.itemDescription = itemDescription;
}
public String getPrice() {
    return price;
}
public void setPrice(String price) {
    this.price = price;
}
public int getImageNumber() {
    return imageNumber;
}
public void setImageNumber(int imageNumber) {
    this.imageNumber = imageNumber;
}

public int getVideoNumber() {
    return videoNumber;
}
public void setVideoNumber(int videoNumber) {
    this.videoNumber = videoNumber;
}

public void setChild(ArrayList<ItemDetails> item_child)
{
    this.item_child = item_child;
}
public ArrayList<ItemDetails> getChild()
{
    return this.item_child;
}
public void setParent(ArrayList<ItemDetails> item_parent)
{
    this.item_parent = item_parent;
}
public ArrayList<ItemDetails> getParent()
{
    return this.item_parent;
}



private String name ;
private String itemDescription;
private String price;
private int imageNumber;
private int videoNumber;
private ArrayList<ItemDetails> item_child;
    private ArrayList<ItemDetails> item_parent; 
}

My class:

我的课：

static class ViewHolder {
    TextView txt_itemName;
    TextView txt_itemDescription;
    TextView txt_itemPrice;
    ImageView itemImage;
    ArrayList<ItemDetails> item_parent;
    ArrayList<ItemDetails> item_child;
}

My putExtra:

我的 putExtra：

intObj.putExtra("exerciselist",obj_itemDetails.getChild());

GetChild function :

获取子函数：

public ArrayList<ItemDetails> getChild()
{
   return this.item_child;
}

But I cannot find how am I supposed to write to get arrayList?

但是我找不到我应该如何写来获取arrayList？

ArrayList<ItemDetails> child1 = getIntent().?????????

回答by Simon Dorociak

But i cannot find how am ? supposed to write to get arrayList

但我找不到怎么样？应该写入以获取 arrayList

Short answer: you can't. You can only pass ArrayList<String>and then retrieve it with

简短的回答：你不能。您只能通过ArrayList<String>然后检索它

getIntent().getStringArrayListExtra("key");

But. If you want to pass custom objects via Intent your objects have to implement:

但是。如果您想通过 Intent 传递自定义对象，您的对象必须实现：

• Parcelable interfaceor Serializable interface

• Parcelable interface或者 Serializable interface

You can choose one of them. Both works same but have different implementations.

您可以选择其中之一。两者的工作原理相同，但实现方式不同。

Parcelable interface:

可打包接口：

If you choose Parcelable interface, your ItemDetailsclass have to implement Parcelable. Then you can put it as

如果你选择 Parcelable 接口，你的ItemDetails类必须实现 Parcelable。然后你可以把它作为

intent.putParcelableArrayListExtra("key", value);

and retrieve it as:

并将其检索为：

getIntent().getParcelableArrayListExtra("key");

I won't write you Parcelable implementation because it requires a little more code. Here is nice example.

我不会为您编写 Parcelable 实现，因为它需要更多代码。这是很好的例子。

Serializable interface:

可序列化接口：

If you choose Serializable interface i suggest you to create class named for instance ItemDetailsWrapper that will wrap your ArrayList(s)<ItemDetails>

如果您选择 Serializable 接口，我建议您创建名为 ItemDetailsWrapper 的类，它将包装您的 ArrayList(s)<ItemDetails>

Both i.e. ItemDetailsWrapper and ItemDetails class have to implement Serializable interface. Now you are able to pass it via Intent like this:

即 ItemDetailsWrapper 和 ItemDetails 类都必须实现 Serializable 接口。现在你可以像这样通过 Intent 传递它：

getIntent().putExtra("key", <serializableClass>); // storing 
getIntent().getSerializableExtra("key"); // retrieving

Example of implementation:

实施例：

public class ItemDetailsWrapper implements Serializable {

    private static final long serialVersionUID = 1L;
    private ArrayList<ItemDetails> itemDetails;

    public ItemDetailsWrapper(ArrayList<ItemDetails> items) {
        this.itemDetails = items;
    }

    public ArrayList<ItemDetails> getItemDetails() {
        return itemDetails;
    }
}

public class ItemDetails implements Serializable {

    private static final long serialVersionUID = 1L;

    // getters, setters and properties
}

And how to pass through Activities:

以及如何通过活动：

ItemDetailsWrapper wrapper = new ItemDetailsWrapper(list);
Intent i = new Intent(<context>, <targetActivity>);
i.putExtra("obj", wrapper); // i.putExtra("obj", new ItemDetailsWrapper(list));
// retrieving 
ItemDetailsWrapper wrap = 
                    (ItemDetailsWrapper) getIntent().getSerializableExtra("obj");
ArrayList<ItemDetails> list = wrap.getItemDetails();