defined

问题 So I was trying out the material design support library and when I added the dependency, compiled, and I got this error. I looked at similar problems and tried their solutions but it would not get fixed so I hope you can help me. Here's my logcat: C:\Users\Jan\AndroidStudioProjects\SwagCalculator3\app\build\intermediates\exploded-aar\com.android.support\appcompat-v7\22.2.0\res\values\values.xml Error:(1) Attribute "rippleColor" has already been defined and here is my build.gradle: apply

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Easy way to check that variable is defined in python? How do I check if a variable exists in Python? How do you know whether a variable has been set at a particular place in the code at runtime? This is not always obvious because (1) the variable could be conditionally set, and (2) the variable could be conditionally deleted. I\'m looking for something like defined() in Perl or isset() in PHP or defined? in Ruby