Adding custom return type for marshalling/unmarshalling the data type in AIDL:

In Android application, while working with AIDL, I faced this problem.

If I am going to return any custom datatype or class in interface's functions, then we need to write .aidl and .java file.

For example from my AIDL interface function, I am going to return Rect custom class. Then I have to do the following:


Rect.aidl:
=========
package android.graphics;

// Declare Rect so AIDL can find it and knows that it implements
// the parcelable protocol.
parcelable Rect;


Rect.java
==============


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

public final class Rect implements Parcelable {
    public int left;
    public int top;
    public int right;
    public int bottom;

    public static final Parcelable.Creator<Rect> CREATOR = new
Parcelable.Creator<Rect>() {
        public Rect createFromParcel(Parcel in) {
            return new Rect(in);
        }

        public Rect[] newArray(int size) {
            return new Rect[size];
        }
    };

    public Rect() {
    }

    private Rect(Parcel in) {
        readFromParcel(in);
    }

    public void writeToParcel(Parcel out) {
        out.writeInt(left);
        out.writeInt(top);
        out.writeInt(right);
        out.writeInt(bottom);
    }

    public void readFromParcel(Parcel in) {
        left = in.readInt();
        top = in.readInt();
        right = in.readInt();
        bottom = in.readInt();
    }
}

I have to include this Rect.java in android compilation make file [make];

we should not include the .aidl file in Android.mk for this scenario.

This can happen when we are using NDK compilation. In NDK case, we will include java/include files in Android.mk.

Error:

* in my Android.mk file, I have added:
LOCAL_SRC_FILES += \
        src/com/mycompany/mypackage/Rect.aidl \

But when we compile we will
Aidl: Test <= src/com/mycompany/mypackage//Rect.aidl
src/com/mycompany/mypackage/Rect.aidl:19 aidl can only generate
code for interfaces, not parcelables,
src/com/mycompany/mypackage/Rect.aidl:19 .aidl files that only
declare parcelables don't need to go in the Makefile.

Android Application AIDL error:

In android application, while working with AIDL, I observed an error.
My function is returning the class Employee. But I got the below error

Aidl: huey <= external/testapp/IMyService.aidl
external/testapp/Ioffice.aidl:16: couldn't find import for class com.sundar.Employee
make: *** [out/target/common/obj/JAVA_LIBRARIES/MyService_intermediates/src/com/IMyService.java] Error 1


IMyService.aidl

interface IOffice
{
 Employee get();
};


I have added the Employee.java which is derived from Parcelable class. I have also added this java file in make file.
But still I got this error.

How to resolve it:
I created the Employee.aidl and copied the below contents

package com.MyService;
parcelable Employee;

I copied the Employee.aidl and copied to the folder where Employee.java is there.Afterwards, it is compiling fine without any error.
 But Employee.aidl is not at all added in Android.mk

How to get result from an activity:
=====================================

The following program snippet depicts how we can get result from an activity in an android application.

To launch an activity:
===========================
    Intent pickIntent= new Intent(this,PickServerActivity.class);
    //To launch an activity use below command:
    startActivityForResult(pickIntent, REQUEST_CODE_PICK_SERVER);

within activity, how to set result:
====================================
  Intent intent = new Intent();
  // start intent
   if(bServerSelected)
   {   
      intent.putExtra(ServerIntents.EXTRA_SERVER_NAME, selectedServerName);
      setResult(RESULT_OK, intent);
    } else {
          setResult(RESULT_CANCELED, intent);
     }

To get result from an activity:
====================================

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_CODE_PICK_SERVER) {
            if (resultCode == RESULT_OK) {
                Bundle extras = data.getExtras();
                if (extras != null) {
                    mServerName = extras.getString(EXTRA_SERVER_NAME);
            //Display Selected server from the activity   
                }
           
            }
        }
    }