Reg exp：从文本中提取第一个数字

问题描述

我就是不知道如何从 Textview 中提取第一个数字。

我的文本视图是

"Maximum week limit of this debit card is 300 000 CZK. Limit can be still increased up to 265 944 CZK".

我需要从这个对象中提取 300 000 个数字。

我可以很容易地找到这个 Textview 的 ID 并使用它。请有人帮助我吗？谢谢。

解决方法

您可以使用正则表达式方法：

String input = "Maximum week limit of this debit card is 300 000 CZK. Limit can be still increased up to 265 944 CZK";
String firstNum = input.replaceAll("^.*?(\\d[0-9 ]*).*$","$1");
System.out.println("First number is: " + firstNum);

打印：

First number is: 300 000

这里的策略是使用正则表达式来捕获第一个数字。这是逻辑：

^                 from the start of the string
    .*?           match all content up to,but not including,the first digit
    (\\d[0-9 ]*)  then match and capture any number of digits or space separators
    .*            match the rest of the input
$                 end of the input

,

参考：https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html 在这里您可以测试您的正则表达式 https://regexr.com/

    final String REGX1 = "([0-9]+ [0-9]+)";
    final String REGX2 = "([0-9]+)";
    String sample = "Maximum week limit of this debit card is 300 000 CZK. Limit can be still increased up to 265 944 CZK";
    
    Pattern pattern1 = Pattern.compile(REGX1);
    Pattern pattern2 = Pattern.compile(REGX2);
    
    Matcher pm1 = pattern1.matcher(sample);
    Matcher pm2 = pattern2.matcher(sample);
    
    System.out.println("1. REGX");
    System.out.println("--------------------------------");
    int index = 1;
    while(pm1.find())
    {
        System.out.println(index+". "+pm1.group(0));
        index++;
    }
    
    System.out.println("--------------------------------");
    System.out.println("2. REGX");
    System.out.println("--------------------------------");
    
    index = 1;
    while(pm2.find())
    {
        System.out.println(index+". "+pm2.group(0));
        index++;
    }

Output

1. REGX
--------------------------------
1. 300 000
2. 265 944
--------------------------------
2. REGX
--------------------------------
1. 300
2. 000
3. 265
4. 944