This Activity already has an action bar supplied by the window decor

问题： 

Caused by: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
        at androidx.appcompat.app.AppCompatDelegateImpl.setSupportActionBar(AppCompatDelegateImpl.java:581)
        at androidx.appcompat.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:183)
        at com.example.mykotlin1.AddUpdateDishActivity.setupActionBar(AddUpdateDishActivity.kt:22)
        at com.example.mykotlin1.AddUpdateDishActivity.onCreate(AddUpdateDishActivity.kt:17)
        at android.app.Activity.performCreate(Activity.java:8000)
        at android.app.Activity.performCreate(Activity.java:7984)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) 
 

问题描述：通过如下代码给activity设置actionbar

    private fun setupActionBar(){
        setSupportActionBar(mBinding.toolbarAddDishActivity)
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
        mBinding.toolbarAddDishActivity.setNavigationOnClickListener {
            onBackPressed()
        }
    }

mainfest中activity没有设置theme，默认是有actionbar的

原因：使用代码设置actionbar之前，先设置activity的theme为无actionbar，然后再调用代码

解决办法：

设置activity为noactionbar

 自定义theme：