在AOSP源码全局搜了一下包含Util关键字的类，整理出这个列表供大家参考：
// 系统
./android/database/DatabaseUtils.java
./android/transition/TransitionUtils.java
./android/view/animation/AnimationUtils.java
./android/view/ViewAnimationUtils.java
./android/webkit/URLUtil.java
./android/bluetooth/le/BluetoothLeUtils.java
./android/gesture/GestureUtils.java
./android/text/TextUtils.java
./android/text/format/DateUtils.java
./android/os/FileUtils.java
./android/os/CommonTimeUtils.java
./android/net/NetworkUtils.java
./android/util/MathUtils.java
./android/util/TimeUtils.java
./android/util/ExceptionUtils.java
./android/util/DebugUtils.java
./android/drm/DrmUtils.java
./android/media/ThumbnailUtils.java
./android/media/ImageUtils.java
./android/media/Utils.java
./android/opengl/GLUtils.java
./android/opengl/ETC1Util.java
./android/telephony/PhoneNumberUtils.java
// 设计和支持库
./design/src/android/support/design/widget/ViewGroupUtils.java
./design/src/android/support/design/widget/ThemeUtils.java
./design/src/android/support/design/widget/ViewUtils.java
./design/lollipop/android/support/design/widget/ViewUtilsLollipop.java
./design/base/android/support/design/widget/AnimationUtils.java
./design/base/android/support/design/widget/MathUtils.java
./design/honeycomb/android/support/design/widget/ViewGroupUtilsHoneycomb.java
./v7/recyclerview/src/android/support/v7/widget/helper/ItemTouchUIUtil.java
./v7/recyclerview/src/android/support/v7/widget/helper/ItemTouchUIUtilImpl.java
./v7/recyclerview/src/android/support/v7/util/MessageThreadUtil.java
./v7/recyclerview/src/android/support/v7/util/AsyncListUtil.java
./v7/recyclerview/src/android/support/v7/util/ThreadUtil.java
./v7/recyclerview/tests/src/android/support/v7/widget/AsyncListUtilLayoutTest.java
./v7/recyclerview/tests/src/android/support/v7/util/AsyncListUtilTest.java
./v7/recyclerview/tests/src/android/support/v7/util/ThreadUtilTest.java
./v7/appcompat/src/android/support/v7/graphics/drawable/DrawableUtils.java
./v7/appcompat/src/android/support/v7/widget/DrawableUtils.java
./v7/appcompat/src/android/support/v7/widget/ThemeUtils.java
./v7/appcompat/src/android/support/v7/widget/ViewUtils.java
./v4/tests/java/android/support/v4/graphics/ColorUtilsTest.java
./v4/jellybean-mr1/android/support/v4/text/TextUtilsCompatJellybeanMr1.java
./v4/jellybean/android/support/v4/app/BundleUtil.java
./v4/jellybean/android/support/v4/app/NavUtilsJB.java
./v4/java/android/support/v4/app/NavUtils.java
./v4/java/android/support/v4/database/DatabaseUtilsCompat.java
./v4/java/android/support/v4/graphics/ColorUtils.java
./v4/java/android/support/v4/text/TextUtilsCompat.java
./v4/java/android/support/v4/util/TimeUtils.java
./v4/java/android/support/v4/util/DebugUtils.java
./v4/java/android/support/v4/content/res/TypedArrayUtils.java
