question: public void enter ( ) { cancel ( ) ; final int radiusDuration = ( int ) ( 1000 * Math . sqrt ( mOuterRadius / WAVE_TOUCH_DOWN_ACCELERATION * mDensity ) + 0.5 ) ; final ObjectAnimator radius = ObjectAnimator . ofFloat ( this , "radiusGravity" , 1 ) ; radius . setAutoCancel ( true ) ; radius . setDuration ( radiusDuration ) ; radius . setInterpolator ( LINEAR_INTERPOLATOR ) ; radius . setStartDelay ( RIPPLE_ENTER_DELAY ) ; final ObjectAnimator cX = ObjectAnimator . ofFloat ( this , "xGravity" , 1 ) ; cX . setAutoCancel ( true ) ; cX . setDuration ( radiusDuration ) ; cX . setInterpolator ( LINEAR_INTERPOLATOR ) ; cX . setStartDelay ( RIPPLE_ENTER_DELAY ) ; final ObjectAnimator cY = ObjectAnimator . ofFloat ( this , "yGravity" , 1 ) ; cY . setAutoCancel ( true ) ; cY . setDuration ( radiusDuration ) ; cY . setInterpolator ( LINEAR_INTERPOLATOR ) ; cY . setStartDelay ( RIPPLE_ENTER_DELAY ) ; mAnimRadius = radius ; mAnimX = cX ; mAnimY = cY ; radius . start ( ) ; cX . start ( ) ; cY . start ( ) ; }
target:  Starts the enter animation.