网站页面切换效果,抖音代运营图片,如何把网站点击连接到百度商桥,电影网站做淘客1、Flutter的数据基本类型
Dart语言里一切皆为对象#xff0c;所以如果没有将变初始化,那么它的默认值为null
Number(int、doubkle)StringBoolean(bool) List Map2、测试代码 void testData() {//Number包含了int和doubleint a 4;int b 8;print(a b);int a1;if (a null)…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)StringBoolean(bool) List Map2、测试代码 void testData() {//Number包含了int和doubleint 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 wordpublic static void main1;print(hello);var word hello wordpublic 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 公众号记得关注我。
