flutter 可选参数

在flutter 里面传参数 option param 是非常有意思的

var user = new Uu("jack");
 var user2 = new Uu("toly",address: "shenzhen");
 print( "${user.name}+${user.address}" );
 print( "${user2.name}+${user2.address}" );
  printPerson1("jack");
  printPerson1("jack",age:20,gender: "man");
  printPerson2("tt");
  printPerson2("tt",33,);
  printPerson2("tt",33,"women");

class Uu{
  String name;
  String address;

  Uu(this.name, {this.address});
  say(){

  }
}
printPerson1(String name, {int age=30, String gender="FEMALE"}) {
  print("name=$name,age=$age,gender=$gender");
}
printPerson2(String name, [int age=18, String gender="MALE"]) {
  print("name=$name,age=$age,gender=$gender");
}

打印结果

jack+null
toly+shenzhen
name=jack,age=30,gender=FEMALE
name=jack,age=20,gender=man
name=tt,age=18,gender=MALE
name=tt,age=33,gender=MALE
name=tt,age=33,gender=women

仔细看，体会体会，有传参数，这个参数就会更改，没有传的就会使用默认值