dar中list,map常用属性和方法

dar中list,map常用属性和方法

list常用属性和方法

常用属性

1,length 获取list的长度

main() {var list = ['red','yellow','pink'];print(list.length);
}

2,判断是否为空

main() {var list = ['red','yellow','pink'];print(list.isEmpty);
}

3,判断不为空

main() {var list = ['red','yellow','pink'];print(list.isNotEmpty);
}

4，数组翻转

main() {var list = ['red','yellow','pink'];List());
}
(pink, yellow, red)

常用方法

1，增加数据add

main() {var list = ['red','yellow','pink'];list.add("green");print(list);
}
[red, yellow, pink, green]

2，查找数据indexOf,查找到返回索引，查找不到返回-1

main() {var list = ['red','yellow','pink'];var res = list.indexOf('yellow');print(res);}  1

3,删了数据remove(‘值’),removeAt(索引)

main() {var list = ['red','yellow','pink'];ve('yellow');veAt(1);print(list);}  
[red]

4,修改数据fillRange(start,end,value) 不包含end

main() {var list = ['red','yellow','pink'];list.fillRange(1, 2,'green');print(list);}[red, green, pink]

5, 给指定位置插入数据insert(index,value) 从index开始插入

main() {var list = ['red','yellow','pink'];list.insert(1, 'green');print(list);
}[red, green, yellow, pink] main() {var list = ['red','yellow','pink'];list.insertAll(1, ['green','white']);print(list);} 
[red, green, white, yellow, pink]

6,转换成字符串join(’,’),并不改为原有list

main() {var list = ['red','yellow','pink'];var str = list.join(',');print(str);}red,yellow,pink

7,将字符串转换成数组split(’-’),不改为原有字符串

main() {var str = 'red-yellow-pink';var list = str.split('-');print(list);print(str);}  
[red, yellow, pink]
red-yellow-pink

8，for(var item in list) 循环list

main() {var list = ['red','yellow','pink'];for(var item in list) {print(item);}
}red
yellow
pink

9,map循环环list

main() {var list = [1,2,3,4];var newList = list.map((value) => value * 2);List());
}

10,查看集合满足某个条件any

main() {var list = ['red','yellow','pink'];var f = list.any((value) => value == 'red');print(f);print(list);}

11，通过set不能添加重复集合,所以不能通过索引去获取

main() {var set = new Set();set.add('red');set.add('yellow');set.add('pink');set.add('red');List());
}  [red, yellow, pink]

maps类型常用属性与方法

1,获取所有的key

main() {var person = {'name':'张三','age':20,};print(List());
}[name, age]

2,获取所有的value

main() {var person = {'name':'张三','age':20,};print(List());
}

3,判断属性是否为空isEmpty

main() {var person = {'name':'张三','age':20,};print(person.isEmpty);}
false

常用方法

1,删除指定key的数据remove(key)

main() {var person = {'name':'张三','age':20,};ve('name');print(person);
}
{age: 20}

2,给map对像添加属性addAll({‘key’:‘value’})

main() {var person = {'name':'张三','age':20,};person.addAll({'sex':'男',});print(person);
}{name: 张三, age: 20, sex: 男}

3,查看个字段是否在map内containsKey(key),返回true/false并不改变原有对像

main() {var person = {'name':'张三','age':20,};var boo = ainsKey('name');print(boo);}true

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