Dart syntax

1.main Function time entry , Must have , You can pass parameters when running code
2. There are many ways to name variables ,final and const The difference between
3. No non-zero is true ,
4. Function is not overloaded , There are required and optional parameters , Only optional parameters can have default values
5. There are generics
6. String and variable splicing ￥
7. For printing print
8. Function with arrow , But the condition is that the function body has only one line of code
9. It is recommended to define types for the parameters and return values of each function
10. The assignment operators are ？？=
11. There are abstract classes Abstract method
12. hold datalesswidget Change to datafulwidget Use shortcut keys alt+enter
13. Shortcut key alt+enter+w Extract into widget part
14. Life cycle in Android studio Two calls... Are shown in , Actually only once , This problem does not occur with terminal execution
15stl stf Quickly generate
16.ctrl+alt+b View all implementation classes

17. Cold start （ It's a long time ）, Cold restart （ Only changed build What's in it ）, Hot restart
Put in local pictures ：1. Create a file to put pictures ,2. Change configuration ,3 quote
18.alt+enter Express package widget
19.flatButton By default, there is a certain space between the top and bottom , Because there are properties materialTapTargetSize The default value of , Set no spacing , Set this property to MaterialTapTargetSize.shrinkWrap
It has a certain width and height by default
20. There are factory constructor abstract classes that can be instantiated
21containner You can set the length and width ,center Equivalent to his parent class align