我在activity_main.xml中看不到textview和其他元素布局android studio

Question

This error is displayed:

Render problem - Failed to load AppCompat ActionBar with unknown error.

---

xml (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">

    <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" />

    </android.support.constraint.ConstraintLayout>

Main activity(java):

package net.ggg.ddd.myapp1;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

image of log:

enter image description here

Answer 1

In your styles.xml change

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">

to

<style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">

Answer 2

The main problem is the AppCompat version.I changed the AppCompat version to latest(27.1.1 instead of 28+ or alfa versions and so on).In this case, I have to change the minsdkversion and the targetsdkversion to 27.Then gradle sync again. I have shown this in the picture:

picture