JS,Java,Python语法对比
字符串
| Java | Javascript | Python | 说明 |
|---|---|---|---|
| charAt | charAt | ||
| compareTo | >< | ||
| compareToIgnoreCase | |||
| concat | concat | ||
| contains | includes | ||
| endsWith | endsWith | endswith | |
| getBytes | |||
| getChars | |||
| indexOf(str,from) | indexOf | find | 找不到返回-1 |
| str.search() | 可使用正则 | ||
| isEmpty | length() is 0. | ||
| lastIndexOf | lastIndexOf | rfind | |
| "s".repeat(2) | 's' * 2 | ||
| subSequence(start,end) | |||
| toLowerCase | toLowerCase | lower() | |
| trim | trim | strip | |
| trimStart | lstrip | ||
| trimEnd | rstrip | ||
| length() | length | len(str) | 字符串 |
| length | length | len(arr) | 数组 |
| slice(-12, -6) | [:] | ||
| subString(start,end) | subString(start,end) | 参数不能为负 | |
| substr(start,length) | 指定数目的字符 | ||
| replace | replace | replace(old, new, max) | js非全部替换 |
| charCodeAt | |||
| split | split | split(str,num) |
正则
| Javascript | Java | Python |
|---|---|---|
| p=/[az][xc]/g | p=Pattern.compile("r"); | p= re.compile(r'([a-z]+)' |
| 新建Pattern对象 | 首先import re | |
| p.exec(string) | p.matcher(str) | p.search(str)<==>re.search(reg,str) |
| 数组或null,返回第一个匹配的分组 | 获取Matcher对象 | 任意位置匹配,返回match对象 |
| p.match(str)<==>re.match('www',str). | ||
| 从首字母开始,只匹配一个Match或None | ||
| m.group(0) | m.group(0) | |
| <==>m.group() | <==>m.group() | |
| m.group(1) | m.group(1) | |
| 获取第一个分组 | ||
| m.groupCount;m.start | m.span;m.start | |
| 获取匹配信息 | ||
| 'ixaapzzpaa'.match(/az/g) | p.findall | |
| 数组或null | 数组或空数组 | |
| re.search(pattern, string) | ||
| 返回match对象,无需从头匹配 | ||
| m.replaceAll() | re.sub(pattern, repl, string) | |
| m.matches() | ||
| 是否全局匹配 | ||
| m.lookAt() | ||
| 开头匹配 | ||
| /e/.test("best") | m.find() | |
| 布尔值 | 非开头匹配 | |
| str.matches(reg) | ||
| 全局匹配,返回布尔型 | ||
| /^be[sn]t$/.test("best") | Pattern.matches(reg,str) | |
| 方法 | ||
| StringObj.split([separator) | re.split | |
数组
| Java | Javascript | Python |
|---|---|---|
| 数组新建 | ||
| int a[]=new int[]{1,2,3} | var myCars=["E","SV","B"]; | [1,2,3,] |
| int a[]= {2,3,4,5}; | ||
| splice(start,len) | ||
| slice(start,end) | [:] | |
| [].map(foo,init) | list(map(mul, blist)) | |
| [].filter(foo,init) | filter(fun,list) | |
| every() | all([i > 5 for i in nums]) | |
| some() | any([i % 2 == 0 for i in nums]) | |
[1, 2, 3, 4].forEach(function (elem, index, array) {
this.push(elem * elem);
}, out);
语法
| Java | Javascript | Python | |
|---|---|---|---|
| 不定参数 | |||
| String... args | ... args | * args | |
| 默认参数 | |||
| function say(name='dude') | def print(age=35 ): | ||
| foreach | |||
| for(int : ) | for(v of list) | for in : | |
| 下标遍历 | |||
| for(v in list) | for in: | ||
| new Cat() | new Cat() | Cat() | |
| (x,y) ->x>0 | const foo = bar => bar + 1 | lambda x,y:y*x | |
| obj instanceof class) | x instanceof Array | isinstance(object, classinfo) | |
| typeof() | type() |
for of 可对字符串进行遍历
Java:
ArrayList<Integer> a = new ArrayList<Integer>();
a.add(44);
a.add(66);
a.add(366);
for(int b : a) {
q(String.valueOf(b));
}
for (Integer in : map.keySet()) {
String str = map.get(in);//得到每个key多对用value的值
}
2、通过Map.entrySet使用iterator遍历key和value
Iterator<Map.Entry<Integer, String>> it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<Integer, String> entry = it.next();
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
3、通过Map.entrySet遍历key和value，推荐，尤其是容量大时
for (Map.Entry<Integer, String> entry : map.entrySet()) {
//Map.entry<Integer,String> 映射项（键-值对） 有几个方法：用上面的名字entry
//entry.getKey() ;entry.getValue(); entry.setValue();
//map.entrySet() 返回此映射中包含的映射关系的 Set视图。
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
4、通过Map.values()遍历所有的value，但不能遍历key
for (String v : map.values()) {
System.out.println("value= " + v);
}
jquery:$.each
players.forEach((player) -> System.out.print(player + "; "));
Js#
try {
throw "值为空";
} catch(err) {
txt="本页有一个错误。\n\n";
txt+="错误描述：" + err.message + "\n\n";
txt+="点击确定继续。\n\n";
alert(txt);
}
Python#
try:
raise ValueError
print c
except (IOError ,ZeroDivisionError),x:
print x
else:
print "no error"
print "done"
