使用一天的感覺: 

層級確實減少很多,

但傻瓜式(圖形,拖動式)操作很難用  

左邊的格子里想要的ID始終不出來, 用代碼編輯方式(特別是與鄰近控件的constraint)更實用

一般都要將控件的四個方向都有constraint才不會報錯

最新的 ConstraintLayout  庫導入

//compile 'com.android.support.constraint:constraint-layout:1.0.0-beta5'compile 'com.android.support.constraint:constraint-layout-solver:1.0.0-beta5'
怎么找 ConstraintLayout 庫的版本呢
1.   (SDK根目錄)/extras/m2repository/com/android/support/constraint   這里有兩個工程,如果你更新了的話     進入里面目錄,打開 maven-metadata.xml  可以找到相應的版本號
java.lang.NoSuchMethodError: android.support.constraint.solver.widgets.ConstraintWidgetContainer.setOptimizationLevel(I)Vat android.support.constraint.ConstraintLayout.init(ConstraintLayout.java:456)at android.support.constraint.ConstraintLayout.<init>(ConstraintLayout.java:421)at sun.reflect.NativeConstructoraccessorImpl.newInstance0(Native Method)at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)at java.lang.reflect.Constructor.newInstance(Constructor.java:423)at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:465)at org.jetbrains.android.uiPReview.ViewLoader.loadClass(ViewLoader.java:172)at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:105)at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadView(LayoutlibCallbackImpl.java:186)at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:334)at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:345)at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:245)at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:858)at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)at android.view.LayoutInflater.rInflate(LayoutInflater.java:834)at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)at android.view.LayoutInflater.inflate(LayoutInflater.java:518)at android.view.LayoutInflater.inflate(LayoutInflater.java:397)at com.android.layoutlib.bridge.impl.RendersessionImpl.inflate(RenderSessionImpl.java:324)at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:429)at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:389)at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:548)at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:533)at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:966)at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:533)at com.android.tools.idea.rendering.RenderTask.lambda$inflate$70(RenderTask.java:659)at java.util.concurrent.FutureTask.run(FutureTask.java:266)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)at java.lang.Thread.run(Thread.java:745)