Java String split方法

Java String split方法用于根据给定的分隔符或正则表达式将String拆分为其子串。

例如:

String: [email protected]
Regular Expression: @ 
Output : {"chaitanya", "singh"}

Java 字符串拆分方法

我们在String类中有两种split()方法。

  1. String[] split(String regex):在根据分隔正则表达式拆分输入String后返回一个字符串数组。

  2. String[] split(String regex, int limit):当我们想要限制子串时,使用这个String split方法。此方法与上述方法的唯一区别在于它限制了拆分后返回的字符串数。对于例如split("anydelimiter", 3)将返回仅 3 个字符串的数组,即使字符串中的分隔符超过 3 次也是如此。

如果限制为负,则返回的数组将具有尽可能多的子串,但是当限制为零时,返回的数组将具有除尾随空字符串之外的所有子串。

如果指定正则表达式的语法无效,则抛出PatternSyntaxException

Java String拆分示例

public class SplitExample{
   public static void main(String args[]){
    // This is out input String
    String str = new String("28/12/2013");

    System.out.println("split(String regex):");
    /* Here we are using first variation of java string split method
     * which splits the string into substring based on the regular
     * expression, there is no limit on the substrings
     */
    String array1[]= str.split("/");
    for (String temp: array1){
          System.out.println(temp);
    }

    /* Using second variation of split method here. Since the limit is passed 
     * as 2\. This method would only produce two substrings. 
     */
    System.out.println("split(String regex, int limit) with limit=2:");
    String array2[]= str.split("/", 2);
    for (String temp: array2){
          System.out.println(temp);
    }

    System.out.println("split(String regex, int limit) with limit=0:");
    String array3[]= str.split("/", 0);
    for (String temp: array3){
          System.out.println(temp);
    }

    /* When we pass limit as negative. The split method works same as the first variation
     * because negative limit says that the method returns substrings with no limit.
     */
    System.out.println("split(String regex, int limit) with limit=-5:");
    String array4[]= str.split("/", -5);
    for (String temp: array4){
          System.out.println(temp);
    }
   }
}

输出:

split(String regex):
28
12
2013
split(String regex, int limit) with limit=2:
28
12/2013
split(String regex, int limit) with limit=0:
28
12
2013
split(String regex, int limit) with limit=-5:
28
12
2013

java 字符串拆分方法中零和负限制之间的差异

在上面的示例中,split("/", 0)split("/", -5)返回相同的值,但在某些情况下,结果会有所不同。让我们通过一个例子来看看这两者之间的区别:

String s="bbaaccaa";
String arr1[]= s.split("a", -1);
String arr2[]= s.split("a", 0);

在这种情况下,arr1将具有{"bb","","cc","",""}但是arr2将具有{"bb","","cc"},因为限制零不包括试验空字符串。

让我们看看完整的程序。

public class JavaExample{
   public static void main(String args[]){
    // This is out input String
    String s = new String("bbaaccaa");

    //Splitting with limit as 0
    String arr2[]= s.split("a", 0);
    System.out.println("Zero Limit split:");
    for (String str2: arr2){
       System.out.println(str2);
    }

    //Splitting with negative limit
    String arr1[]= s.split("a", -1);
    System.out.println("Negative Limit split:");
    for (String str: arr1){
       System.out.println(str);
    }

       System.out.println("End of program");
   }
}

输出:

Java String split方法

Java 带有多个分隔符(特殊字符)的字符串拆分

让我们看看我们如何在使用split()方法时传递多个分隔符。在这个例子中,我们基于多个特殊字符拆分输入字符串。

public class JavaExample{
   public static void main(String args[]){
    String s = " ,ab;gh,bc;pq#kk$bb";
    String[] str = s.split("[,;#$]");

    //Total how many substrings? The array length
    System.out.println("Number of substrings: "+str.length);

    for (int i=0; i < str.length; i++) {
        System.out.println("Str["+i+"]:"+str[i]);
    }
   }
}

输出:

Java String split方法

让我们再练习几个例子:

示例:Java String split方法中的正则表达式

public class SplitExample1 { 
    public static void main(String args[]) 
    { 
        String str = "helloxyzhixyzbye"; 
        String[] arr = str.split("xyz"); 

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

输出:

hello
hi
bye

示例:基于空格分割字符串

public class SplitExample2 { 
    public static void main(String args[]) 
    { 
        String str = "My name is Chaitanya";
        //regular expression is a whitespace here 
        String[] arr = str.split(" "); 

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

输出:

My
name
is
Chaitanya

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