Android – Understanding isUserAMonkey Function in ActivityManager

Android R Update:

From Android R, this method always returns false. Google says that this is done "to protect goat privacy":

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this method can
 * now automatically identify goats using advanced goat recognition technology.</p>
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#R}, this method always returns
 * {@code false} in order to protect goat privacy.</p>
 *
 * @return Returns whether the user making this call is a goat.
 */
public boolean isUserAGoat() {
    if (mContext.getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.R) {
        return false;
    }
    return mContext.getPackageManager()
            .isPackageAvailable("com.coffeestainstudios.goatsimulator");
}

Previous answer:

From their source, the method used to return false until it was changed in API 21.

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 * @return whether the user making this call is a goat 
 */
public boolean isUserAGoat() {
    return false;
}

It looks like the method has no real use for us as developers. Someone has previously stated that it might be an Easter egg.

In API 21 the implementation was changed to check if there is an installed app with the package com.coffeestainstudios.goatsimulator

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this method can
 * now automatically identify goats using advanced goat recognition technology.</p>
 *
 * @return Returns true if the user making this call is a goat.
 */
public boolean isUserAGoat() {
    return mContext.getPackageManager()
            .isPackageAvailable("com.coffeestainstudios.goatsimulator");
}

Here is the source and the change.

The answer to the question is actually the combination of comments from @CommonsWare and @Chris. So, for the sake of progeny, I am going to consolidate the comments and make it available in one place.

Basically, there are two predefined constants for the requestCode and they are Activity.RESULT_OK and Activity.RESULT_CANCELLED. However, android developers can also set custom codes for their apps by using the offset Activity.RESULT_FIRST_USER. Doing so ensures that there are no clashes between constants set at the OS level and the app level.

Purely, my opinion, I think that the FIRST USER suffix is meant to refer to developers – just like how end consumer refers to consumers of a said product – who are the first users before the app users.

Below is an example of how you can use this offset,

public static final int MY_RESULT_CODE = Activity.RESULT_FIRST_USER + 1;