What are the methods for intercepting strings in Java?

1 .substring()

This is a more commonly used method.

This method has two forms:

substring(int beginIndex); //提取从索引位置开始至结尾处的字符串部分
substring(int beginIndex,int endIndex); //提取beginIndex开始到endIndex的字符串部分

Instance code:

        String str = "你好，Java练习生";
        //substring(int beginIndex);
        String substring1 = str.substring(3);

        //substring(int beginIndex,int endIndex);
        String substring2 = str.substring(3, 7);

        System.out.println(substring1);//Java练习生
        System.out.println(substring2);//Java

It should be noted that: The counting starts from 0, if it exceeds the character If the string length is too long, an error will be reported:

java.lang.StringIndexOutOfBoundsException: String index out of range:

Calculation position diagram

##2 split() regular expression

is not commonly used, but in certain Especially useful in certain situations.

Format:

String.split("specify delimiter");–returns an array

Example (using English comma as delimiter):

        String str = "good,good,study,day,day,up";
        String[] split = str.split(",");

        for (String s:
             split) {
            System.out.println(s);
        }

3 StringUtils.substring()

You need to import the StringUtils tool class. A combination of many methods.

Because everyone uses different tools, only one type is recorded.

maven import:

        <dependency>
            <groupId>com.lispcast</groupId>
            <artifactId>org.apache.commons.lang</artifactId>
            <version>2.5.0</version>
        </dependency>

• String substring(String str,int start): Avoid abnormally obtaining a substring from the specified String.

• String substring(String str,int start, int end): It can avoid abnormally obtaining a substring from the specified String.

• String substringAfter(String str,String separator): Get the substring after the first occurrence of the separator.

• String substringAfterLast(String str,String separator): Gets the substring after the last occurrence of the separator.

• String substringBefore(String str,String separator): Gets the substring before the first occurrence of the separator.

• String substringBeforeLast(String str,String separator): Gets the substring before the last occurrence of the separator.

• String substringBetween(String str,String tag): Get the String nested between two instances of the same String.

• String substringBetween(String str, String open, String close): Get the string nested between two strings.

Test:

String str = "大家好，我是练习两年半的个人练习生，cxk";

        //- String substring(String str,int start)：避免异常地从指定的String获取一个子字符串。
        String substring1 = StringUtils.substring(str, 4);
        
        //- String substring(String str,int start, int end)：可避免异常地从指定的String获取一个子字符串。
        String substring2 = StringUtils.substring(str, 4, 7);
        
        //- String substringAfter(String str,String separator)：在第一次出现分隔符后获取子字符串。
        String substringAfter = StringUtils.substringAfter(str, "，");
        
        //- String substringAfterLast(String str,String separator)：在最后一次出现分隔符之后获取子字符串。
        String substringAfterLast = StringUtils.substringAfterLast(str, "，");
        
        //- String substringBefore(String str,String separator)：在第一次出现分隔符之前获取子字符串。
        String substringBefore = StringUtils.substringBefore(str, "，");
        
        //- String substringBeforeLast(String str,String separator)：在最后一次出现分隔符之前获取子字符串。
        String substringBeforeLast = StringUtils.substringBeforeLast(str, "，");
        
        //- String substringBetween(String str,String tag)：获取嵌套在同一String的两个实例之间的String。
        String substringBetween1 = StringUtils.substringBetween(str, "，");
        
        // - String  substringBetween(String str, String open, String close)：获取嵌套在两个字符串之间的字符串。
        String substringBetween2 = StringUtils.substringBetween(str, "好", "的");

        System.out.println(substring1);
        System.out.println(substring2);
        System.out.println(substringAfter);
        System.out.println(substringAfterLast);
        System.out.println(substringBefore);
        System.out.println(substringBeforeLast);
        System.out.println(substringBetween1);
        System.out.println(substringBetween2);

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