kotlin xml布局Android Toolbar widget is used to create menus in the apps. We will learn how to create a Toolbar using the XML layout and Kotlin code. We will implement various toolbar properties in an example Android app. Android工具欄小部件用于在應用程序
1. 改進點/基礎 //安全判空
val length = text?.length;//類型轉換
if (object is Car) {var car = object as Ca
}//操作符變化
& and
| or
^ xor
>> shr
<< shl//打印日志
print("123123")
println("asdassda") 2. 字符串 //多行字