如何传递ArrayList <Class> 从一项活动到另一项活动？

Question

I have this ArrayList<ToLet> toLet;

The ToLet class is a POJO class.

Now how can I pass this from one activity to another? What is the best way to do it?

I have gone through the following links..

How to pass an object from one activity to another on Android

How to pass ArrayList<Custom_Object> from one activity to another in Android?

but did not help me.So If anyone knows the answer,let me know

Answer 1

You can also use this for passing ArrayList tolet; one activity to Another activity.

Create the object of your class :-

ToLet obj = new ToLet();

ArrayList<ToLet> tolet;
int size = tolet.getSize();    
Intent ii = new Intent(your_current_class.this, next_class_where_you_want_to_use);
ii.putExtra("listsize",size);

 startActivity(ii);

Now Go to your next class and use :-

Intent intent = getIntent();
String mylistsize = intent.getIntExtra("listsize",default value);

and AndroidMainest.xml file update this activity.

<activity android:name="yourcurrentclass" />
<activity android:name="yournextclass" />

It should solve your query.

Answer 2

When you are creating an object of intent, you can take advantage of following two methods for passing objects between two activities.

putParceble

putSerializable

The following tell you about putParceble

Review Writing Parcelable classes for Android carefully. Here they are using Hashmap to store the values and pass the object to another class.

OR

---

Make one class, ObjectA . In that, I used all the setter and getter methods.

package com.ParcableExample.org;

import android.os.Parcel;
import android.os.Parcelable;

/**
 * A basic object that can be parcelled to
 * transfer between objects.
 */

public class ObjectA implements Parcelable
{
    private String strValue = null;
    private int intValue = 0;

    /**
     * Standard basic constructor for non-parcel
     * object creation.
     */

    public ObjectA()
    {
    }

    /**
     *
     * Constructor to use when re-constructing object
     * from a parcel.
     *
     * @param in a parcel from which to read this object.
     */

    public ObjectA(Parcel in)
    {
        readFromParcel(in);
    }

    /**
     * Standard getter
     *
     * @return strValue
     */
    public String getStrValue()
    {
        return this.strValue;
    }

    /**
     * Standard setter
     *
     * @param strValue
     */

    public void setStrValue(String strValue)
    {
        this.strValue = strValue;
    }


    /**
     * Standard getter
     *
     * @return intValue
     */
    public Integer getIntValue()
    {
        return this.intValue;
    }

    /**
     * Standard setter
     *
     * @param strValue
     */
    public void setIntValue(Integer intValue)
    {
        this.intValue = intValue;
    }

    @Override
    public int describeContents()
    {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags)
    {
        // We just need to write each field into the
        // parcel. When we read from parcel, they
        // will come back in the same order

        dest.writeString(this.strValue);
        dest.writeInt(this.intValue);
    }

    /**
     *
     * Called from the constructor to create this
     * object from a parcel.
     *
     * @param in parcel from which to re-create object.
     */
    public void readFromParcel(Parcel in)
    {
        // We just need to read back each
        // field in the order that it was
        // written to the parcel

        this.strValue = in.readString();
        this.intValue = in.readInt();
    }

    /**
    *
    * This field is needed for Android to be able to
    * create new objects, individually or as arrays.
    *
    * This also means that you can use use the default
    * constructor to create the object and use another
    * method to hyrdate it as necessary.
    */
    @SuppressWarnings("unchecked")
    public static final Parcelable.Creator CREATOR = new Parcelable.Creator()
    {
        @Override
        public ObjectA createFromParcel(Parcel in)
        {
            return new ObjectA(in);
        }

        @Override
        public Object[] newArray(int size)
        {
            return new ObjectA[size];
        }
    };
}

Then make one Activity that is used to send the Object to another activity.

package com.ParcableExample.org;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class ParcableExample extends Activity
{
    private Button btnClick;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        initControls();
    }

    private void initControls()
    {
        btnClick = (Button)findViewById(R.id.btnClick);
        btnClick.setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View arg0)
            {
                ObjectA obj = new ObjectA();
                obj.setIntValue(1);
                obj.setStrValue("Chirag");

                Intent i = new Intent(ParcableExample.this,MyActivity.class);
                i.putExtra("com.package.ObjectA", obj);
                startActivity(i);
            }
        });
    }
}

Now finally make one another activity that read the Object and get the value from that.

package com.ParcableExample.org;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class MyActivity extends Activity
{
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Bundle bundle = getIntent().getExtras();
        ObjectA obj = bundle.getParcelable("com.package.ObjectA");

        Log.i("---------- Id   ",":: "+obj.getIntValue());
        Log.i("---------- Name ",":: "+obj.getStrValue());
    }
}