JAVA Pattern.matches的使用

1.首先阅读Pattern.matches的API：

boolean java.util.regex.Pattern.matches(String regex, CharSequence input)

Compiles the given regular expression and attempts to match the given input against it. 

An invocation of this convenience method of the form 

 Pattern.matches(regex, input);
behaves in exactly the same way as the expression 
 Pattern.compile(regex).matcher(input).matches()

If a pattern is to be used multiple times, compiling it once and reusing it will be more efficient than invoking this method each time. 
Parameters:regex The expression to be compiledinput The character sequence to be matchedReturns:whether or not the regular expression matches on the inputThrows
:PatternSyntaxException – 
If the expression’s syntax is invalid

什么意思，看不懂没关系，看下面的例子

 String tx ="s_safasfasfqewgsvzvdsvgf.";
 boolean t = Pattern.matches("^[a-zA-Z]\\w*$", tx);
 System.out.println(t);

代码的意思就是  ：字符串tx是不是匹配正则表达式^[a-zA-Z]\\w*$；，如果匹配就返回ture；如果不匹配就返回false。

知识点2：^[a-zA-Z]\\w*$ 

^表示正则表达式的开始；

$表示正常表达式的结尾；

[a-zA-z]表示任意一个英文字母，不区分大小写

\\w* 表示任意一个字符，字符类型为：数字，下划线和字母

结合起来就是：一个以字母开头的以，下划线和数组字母构成的字符串！

现在我们在来看看JDK的文档：

boolean java.util.regex.Pattern.matches(String regex, CharSequence input)

Compiles the given regular expression and attempts to match the given input against it. 

An invocation of this convenience method of the form 

Pattern.matches(regex, input);
behaves in exactly the same way as the expression 
Pattern.compile(regex).matcher(input).matches()

If a pattern is to be used multiple times, compiling it once and reusing it will be more efficient than invoking this method each time. 
Parameters:regex The expression to be compiledinput The character sequence to be matchedReturns:whether or not the regular expression matches on the inputThrows
:PatternSyntaxException – 
If the expression’s syntax is invalid

说明还可以这样使用：

boolean ty=Pattern.compile("^[a-zA-Z]\\w*$").matcher(tx).matches();

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