Java 检查字符串是否包含点
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Checking if a string contains a dot
提问by Robin De Baets
Today I was trying to detect if a string contains a dot, but my code isn't working
今天我试图检测一个字符串是否包含一个点，但我的代码不起作用
String s = "test.test";
if(s.contains("\.")) {
System.out.printLn("string contains dot");
}
采纳答案by HaveNoDisplayName
contains()method of String class does not take regular expression as a parameter, it takes normal text.
contains()String类的方法不以正则表达式为参数，它以普通文本为参数。
String s = "test.test";
if(s.contains("."))
{
System.out.println("string contains dot");
}
回答by Luiggi Mendoza
String#containsreceives a plain CharacterSequencee.g. a String, not a regex. Remove the \\from there.
String#contains接收一个普通的CharacterSequence例如 a String，而不是一个正则表达式。\\从那里删除。
String s = "test.test";
if (s.contains(".")) {
System.out.println("string contains dot");
}
回答by Jaeger Kor
You only need
你只需要
s.contains (".");
回答by svarog
Sometimes you will need to find a character and do something with it, a similar check can also be done using .indexOf('.'), for instance:
有时你需要找到一个字符并用它做一些事情，也可以使用类似的检查来完成.indexOf('.')，例如：
"Mr. Anderson".indexOf('.'); // will return 2
The method will return the index position of the dot, if the character doesn't exist, the method will return -1, you can later do a check on that.
该方法将返回点的索引位置，如果该字符不存在，该方法将返回-1，您可以稍后进行检查。
if ((index = str.indexOf('.'))>-1) { .. do something with index.. }
回答by Erangad
Try this,
尝试这个，
String k="test.test";
String pattern="\.";
Pattern p=Pattern.compile(pattern);
Matcher m=p.matcher(k);
if(m.find()){
System.out.println("Contains a dot");
}
}
回答by Demon App Programmer
The easiest way is to check with a .contains() statement.(.contains() only works for strings) From
最简单的方法是使用 .contains() 语句进行检查。（.contains() 仅适用于字符串）来自
String s = "test.test";
if(s.contains("\.")) {
System.out.printLn("string contains dot");
}
to
到
String s = "test.test";
if(s.contains(".")) {
System.out.printLn("string contains dot");
}
Do like this to check any symbol or character in a string
这样做以检查字符串中的任何符号或字符
