[英]How to check a string contains only digits and one occurrence of a decimal point?
My idea is something like this but I dont know the correct code 我的想法是这样的,但我不知道正确的代码
if (mystring.matches("[0-9.]+")){
//do something here
}else{
//do something here
}
I think I'm almost there. 我想我差不多了。 The only problem is multiple decimal points can be present in the string.
唯一的问题是字符串中可能存在多个小数点。 I did look for this answer but I couldn't find how.
我确实找到了这个答案,但我找不到如何。
If you want to -> make sure it's a number AND has only one decimal <- try this RegEx instead: 如果你想 - > 确保它是一个数字并且只有一个小数 < - 请尝试使用此RegEx:
if(mystring.matches("^[0-9]*\\.?[0-9]*$")) {
// Do something
}
else {
// Do something else
}
This RegEx states: 此RegEx声明:
Note that bullet point #2 is to catch someone entering ".02" for example. 请注意,项目符号#2是为了捕获某人输入“.02”。
If that is not valid make the RegEx: "^[0-9]+\\\\.?[0-9]*$"
如果这是无效的,请使用RegEx:
"^[0-9]+\\\\.?[0-9]*$"
I think using regexes complicates the answer. 我认为使用正则表达式会使答案复杂化。 A simpler approach is to use
indexOf()
and substring()
: 一种更简单的方法是使用
indexOf()
和substring()
:
int index = mystring.indexOf(".");
if(index != -1) {
// Contains a decimal point
if (mystring.substring(index + 1).indexOf(".") == -1) {
// Contains only one decimal points
} else {
// Contains more than one decimal point
}
}
else {
// Contains no decimal points
}
You could use indexOf()
and lastIndexOf()
: 您可以使用
indexOf()
和lastIndexOf()
:
int first = str.indexOf(".");
if ( (first >= 0) && (first - str.lastIndexOf(".")) == 0) {
// only one decimal point
}
else {
// no decimal point or more than one decimal point
}
Simplest 简单
Example: 例:
"123.45".split(".").length();
If you want to check if a number (positive) has one dot and if you want to use regex, you must escape the dot, because the dot means "any char" :-) 如果你想检查一个数字(正数)是否有一个点,如果你想使用正则表达式,你必须转义点,因为点意味着“任何字符”:-)
see http://docs.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html 见http://docs.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html
Predefined character classes
. Any character (may or may not match line terminators)
\d A digit: [0-9]
\D A non-digit: [^0-9]
\s A whitespace character: [ \t\n\x0B\f\r]
\S A non-whitespace character: [^\s]
\w A word character: [a-zA-Z_0-9]
\W A non-word character: [^\w]
so you can use something like 所以你可以使用像
System.out.println(s.matches("[0-9]+\\.[0-9]+"));
ps. PS。 this will match number such as 01.1 too.
这也将匹配01.1等数字。 I just want to illustrate the \\\\.
我只想说明\\\\。
int count=0;
For(int i=0;i<mystring.length();i++){
if(mystring.charAt(i) == '/.') count++;
}
if(count!=1) return false;
Use the below RegEx its solve your proble 使用以下RegEx解决您的问题
allow 2 decimal places ( eg 0.00 to 9.99) 允许2个小数位(例如0.00到9.99)
^[0-9]{1}[.]{1}[0-9]{2}$ This RegEx states: 1. ^ means the string must start with this. 2. [0-9] accept 0 to 9 digit. 3. {1} number length is one. 4. [.] accept next character dot. 5. [0-9] accept 0 to 9 digit. 6. {2} number length is one.
allow 1 decimal places ( eg 0.0 to 9.9) 允许1位小数(例如0.0到9.9)
^[0-9]{1}[.]{1}[0-9]{1}$ This RegEx states: 1. ^ means the string must start with this. 2. [0-9] accept 0 to 9 digit. 3. {1} number length is one. 4. [.] accept next character dot. 5. [0-9] accept 0 to 9 digit. 6. {1} number length is one.
I create myself to solve exactly question's problem. 我创造自己来解决问题的确切问题。 I'll share you guys the regex:
我会和你们分享正则表达式:
^(\\d)*(\\.)?([0-9]{1})?$
Take a look at this Online Regex to see work properly 看看这个在线正则表达式 ,看看是否正常工作
Refer documentation if you wish continue to custom the regex 如果您希望继续自定义正则表达式,请参阅文档
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