Android Studio布局编辑器

Question

Hey i just started using the Android Studio Layout Editor, so i just made a new projcect with basic activity, so it jsut has a hello world text in the middle. I followed all the instructions from: https://developer.android.com/training/basics/firstapp/building-ui But mine looks nothing like that, mine is just a blue rectangle with nothing on it. I noticed some errors in the Warning and Errors message tab:

1 Rendering Error
Failed to find style 'coordinatorLayoutStyle' in current theme   Tip: Try to refresh the layout. 
1 Using Private resources: 
The resource @string/appbar_scrolling_view_behavior is marked as private in com.android.support:design  Private resources should not be referenced; the may not be present everywhere, and even where they are they may disappear without notice.  To fix this, copy the resource into your own project instead.
1 Missing Styles:
Missing styles. Is the correct theme chosen for this layout?  Use the Theme combo box above the layout to choose a different layout, or fix the theme style references.
1 Failed to instance one or more classes
The following classes could not be instantiated:
- android.support.design.widget.CoordinatorLayout (Open Class, Show Exception, Clear Cache)
- android.support.design.widget.AppBarLayout (Open Class, Show Exception, Clear Cache)
 Tip: Use View.isInEditMode() in your custom views to skip code or show sample data when shown in the IDE.  If this is an unexpected error you can also try to build the project, then manually refresh the layout.  Exception Details java.lang.ClassNotFoundException: android.view.View$OnUnhandledKeyEventListener Copy stack to clipboard

I have no idea why this is happening since i very recently installed Android Studio and was not expecting any errors with a brand new basic project. Hope you can help, thanks!

EDIT: THE XML TEXT AFTER I DELETED THE HELLO WORLD AND SIMPLE DRAGGED AND DOPPED AN EDIT TEXT

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/editText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName"
        android:text="Name"
        tools:layout_editor_absoluteX="126dp"
        tools:layout_editor_absoluteY="158dp" />
</android.support.constraint.ConstraintLayout>

ANOTHER EDIT: When hovering over the EditText (becouse it is red underlined) it says This view is not constrained.

Answer 1

You're using a constraint layout but your text view is using absolute position. tools:layout_editor_absoluteX="126dp" & tools:layout_editor_absoluteY="158dp" .

https://developer.android.com/training/constraint-layout/

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

Also, your app theme is looking for coordinatorLayout.

<style name="AppTheme.NoActionBar">
  <item name="coordinatorLayoutStyle">@style/Widget.Design.CoordinatorLayout</item>
</style>