字符串

单引号或者双引号

• 赋值

String a = 'ducafecat';
String b = "ducafecat";

• 区别 转义分隔符

final myString = 'Bob\'s dog';            // Bob's dog
final myString = "a \"quoted\" word";     // a "quoted" word

final myString = "Bob's dog";             // Bob's dog
final myString = 'a "quoted" word';       // a "quoted" word

final value = '"quoted"';                 // "quoted"
final myString = "a $value word";         // a "quoted" word

字符串模板

var a = 123;
String b = 'ducafecat : ${a}';
print(b);

字符串连接

var a = 'hello' + ' ' + 'ducafecat';
var a = 'hello'' ''ducafecat';
var a = 'hello'   ' '     'ducafecat';

var a = 'hello'
' '
'ducafecat';

var a = '''
hello word
this is multi line
''';

var a = """
hello word
this is multi line
""";

print(a);

转义符号

var a = 'hello word \n this is multi line';
print(a);

hello word
 this is multi line

取消转义

var a = r'hello word \n this is multi line';
print(a);

hello word \n this is multi line

搜索

var a = 'web site ducafecat.tech';
print(a.contains('ducafecat'));
print(a.startsWith('web'));
print(a.endsWith('tech'));
print(a.indexOf('site'));

true
true
true
4

提取数据

var a = 'web site ducafecat.tech';
print(a.substring(0,5));
var b = a.split(' ');
print(b.length);
print(b[0]);

web s
3
web

大小写转换

var a = 'web site ducafecat.tech';
print(a.toLowerCase());
print(a.toUpperCase());

web site ducafecat.tech
WEB SITE DUCAFECAT.TECH

裁剪 判断空字符串

print('    hello word     '.trim());
print(''.isEmpty);

hello word
true

替换部分字符

print('hello word word!'.replaceAll('word', 'ducafecat'));

hello ducafecat ducafecat!

字符串创建

var sb = StringBuffer();
sb..write('hello word!')
..write('my')
..write(' ')
..writeAll(['web', 'site', 'https://ducafecat.tech']);
print(sb.toString());

hello word!my websitehttps://ducafecat.tech