Proper use cases for Android UserManager.isUserAGoat()?

2021-6-3 anglehua

I was looking at the new APIs introduced in Android 4.2. While looking at the UserManager class I came across the following method:

public boolean isUserAGoat()

Used to determine whether the user making this call is subject to teleportations.

Returns whether the user making this call is a goat.

How and when should this be used?


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.



I don't know if this was "the" official use case, but the following produces a warning in Java (that can further produce compile errors if mixed with return statements, leading to unreachable code):

while (1 == 2) { // Note that "if" is treated differently
    System.out.println("Unreachable code");
}

However this is legal:

while (isUserAGoat()) {
    System.out.println("Unreachable but determined at runtime, not at compile time");
}

So I often find myself writing a silly utility method for the quickest way to dummy out a code block, then in completing debugging find all calls to it, so provided the implementation doesn't change this can be used for that.

JLS points out if (false) does not trigger "unreachable code" for the specific reason that this would break support for debug flags, i.e., basically this use case (h/t @auselen). (static final boolean DEBUG = false; for instance).

I replaced while for if, producing a more obscure use case. I believe you can trip up your IDE, like Eclipse, with this behavior, but this edit is 4 years into the future, and I don't have an Eclipse environment to play with.



采集自互联网,如有侵权请联系本人

Powered by emlog 京ICP备15036472号-3 sitemap