从一个活动传递到另一个ArrayList中

问题描述

我试图从一个活动传递完整的ArrayList到另一个。

I am trying to pass the complete arraylist from one activity to another.

我曾尝试这样的方式..

i have tried like this way..

arraylist=new ArrayList<HashMap<String,Object>>();


    Intent i= new Intent(ListActivity.this,search.class);
               i.putExtra("arraylist", arraylist);
               startActivity(i);

有人能帮助我@thanks

Could somebody help me out @thanks

推荐答案

这是行不通的，因为在Java中对象类是不可序列。见this问题一个解释为什么。

This will not work because the Object class in Java is not serializable. See this question for an explanation as to why.

的 Intent.putExtra（）方法需要实现Serializable接口类型，对象不那么因此它不会工作，实现这一点。我建议，而不是一个的HashMap＆LT;弦乐，对象＆gt; 您使用实现Serializable接口的一个更具体的类型替换对象。请参阅如何做到这一点这。

The Intent.putExtra() method requires a type that implements the serializable interface, Object does not implement this so consequently it will not work. I would suggest rather than having a HashMap<String,Object> you replace the Object with a more specific type that implements the Serializable interface. See this tutorial for how to do this.

更新

如果您传递大量数据，则可能是序列化和反序列化相关的一个相当显著的开销。因此它可能会使用静态Singleton类来存储数组列表是值得的。在code下面的示例展示了如何实现这一点：

If the data you are passing is large there could be a fairly significant overhead associated with serializing and deserializing. Consequently it might be worth using a Static Singleton class to store the arraylist. The code sample below shows how you could implement this:

public class DataStore {
    private static final DataStore instance = new DataStore ();
    private arraylist = new ArrayList<HashMap<String,Object>>();

    //Private constructor
    private DataStore () {}

    //Class is only accessible through this method
    public static Singleton getInstance() {
        return instance;
    }

    //Accessors for your data
    private ArrayList<HashMap<String,Object>> getArrayList()
    {
         return arraylist;
    }

    private void setArrayList(ArrayList<HashMap<String,Object>> value)
    {
         arraylist = value;
    }
}

有关引用这里是一个上静态单身。

For reference here is a tutorial on static singletons.

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