Flutter之基本数据类型测试

1、Flutter的数据基本类型

Dart语言里一切皆为对象，所以如果没有将变初始化,那么它的默认值为null

    Number(int、doubkle)
    String
    Boolean(bool)
    List
    Map

 
2、测试代码

     void testData() {
     
        //Number包含了int和double
        int a = 4;
        int b = 8;
        print(a + b);
        int a1;
        if (a == null) {
          print('a == null');
        } else {
          print('a != null');
        }
     
        if (a1 == null) {
          print('a1 == null');
        } else {
          print('a1 != null');
        }
     
        double c = 5.9;
        double d = 6.4;
        print(c + d);
     
        //String类型
        var chen = 'chen';
        var yu = 'yu';
        var name = chen + yu;
        print(name);
     
        var hello = '''
        hello word
        public static void main1
        ''';
        print(hello);
     
        var word = """
        hello word
        public stati void main2
        """;
        print(word);
     
     
        //Boolean类型
        bool isSelect = false;
        if (isSelect) {
          print('isSelect is true');
        } else {
          print('isSelect is false');
        }
     
     
        //List类型
        var list = [];
        list.add(1);
        list.add(2);
        print(list);
        print('size is ${list.length}');
     
        list.removeAt(0);
        print(list);
        print('size is ${list.length}');
     
     
        //Map类型
        var week = {'one':'test1', 'two':'test2'};
        print(week);
        print('week length is ${week.length}');
        week.putIfAbsent('three', () => 'test3');
        print(week);
        print('week length is ${week.length}');
      }


 
3、运行结果

    I/flutter (24359): 12
    I/flutter (24359): a != null
    I/flutter (24359): a1 == null
    I/flutter (24359): 12.3
    I/flutter (24359): chenyu
    I/flutter (24359):     hello word
    I/flutter (24359):     public static void main1
    I/flutter (24359):     
    I/flutter (24359):     hello word
    I/flutter (24359):     public stati void main2
    I/flutter (24359):     
    I/flutter (24359): isSelect is false
    I/flutter (24359): [1, 2]
    I/flutter (24359): size is 2
    I/flutter (24359): [2]
    I/flutter (24359): size is 1
    I/flutter (24359): {one: test1, two: test2}
    I/flutter (24359): week length is 2
    I/flutter (24359): {one: test1, two: test2, three: test3}
    I/flutter (24359): week length is 3

 

作者：chen.yu
深信服三年半工作经验，目前就职游戏厂商，希望能和大家交流和学习,
微信公众号：编程入门到秃头 或扫描下面二维码
零基础入门进阶人工智能(链接)