我想通过分隔符“-”将字符串“004-034556”拆分为两个字符串:

part1 = "004";
part2 = "034556";

这意味着第一个字符串将包含“-”之前的字符,第二个字符串将包括“-”之后的字符。

我还想检查字符串中是否有“-”。


当前回答

我查看了所有答案,发现所有答案都是第三方许可或基于正则表达式的。

下面是我使用的一个很好的哑实现:

/**
 * Separates a string into pieces using
 * case-sensitive-non-regex-char-separators.
 * <p>
 * &nbsp;&nbsp;<code>separate("12-34", '-') = "12", "34"</code><br>
 * &nbsp;&nbsp;<code>separate("a-b-", '-') = "a", "b", ""</code>
 * <p>
 * When the separator is the first character in the string, the first result is
 * an empty string. When the separator is the last character in the string the
 * last element will be an empty string. One separator after another in the
 * string will create an empty.
 * <p>
 * If no separators are set the source is returned.
 * <p>
 * This method is very fast, but it does not focus on memory-efficiency. The memory
 * consumption is approximately double the size of the string. This method is
 * thread-safe but not synchronized.
 *
 * @param source    The string to split, never <code>null</code>.
 * @param separator The character to use as splitting.
 * @return The mutable array of pieces.
 * @throws NullPointerException When the source or separators are <code>null</code>.
 */
public final static String[] separate(String source, char... separator) throws NullPointerException {
    String[] resultArray = {};
    boolean multiSeparators = separator.length > 1;
    if (!multiSeparators) {
        if (separator.length == 0) {
            return new String[] { source };
        }
    }
    int charIndex = source.length();
    int lastSeparator = source.length();
    while (charIndex-- > -1) {
        if (charIndex < 0 || (multiSeparators ? Arrays.binarySearch(separator, source.charAt(charIndex)) >= 0 : source.charAt(charIndex) == separator[0])) {
            String piece = source.substring(charIndex + 1, lastSeparator);
            lastSeparator = charIndex;
            String[] tmp = new String[resultArray.length + 1];
            System.arraycopy(resultArray, 0, tmp, 1, resultArray.length);
            tmp[0] = piece;
            resultArray = tmp;
        }
    }
    return resultArray;
}

其他回答

使用Java 8:

    List<String> stringList = Pattern.compile("-")
            .splitAsStream("004-034556")
            .collect(Collectors.toList());

    stringList.forEach(s -> System.out.println(s));

使用Regex使用多个字符拆分字符串

public class StringSplitTest {
     public static void main(String args[]) {
        String s = " ;String; String; String; String, String; String;;String;String; String; String; ;String;String;String;String";
        //String[] strs = s.split("[,\\s\\;]");
        String[] strs = s.split("[,\\;]");
        System.out.println("Substrings length:"+strs.length);
        for (int i=0; i < strs.length; i++) {
            System.out.println("Str["+i+"]:"+strs[i]);
        }
     }
  }

输出:

Substrings length:17
Str[0]:
Str[1]:String
Str[2]: String
Str[3]: String
Str[4]: String
Str[5]: String
Str[6]: String
Str[7]:
Str[8]:String
Str[9]:String
Str[10]: String
Str[11]: String
Str[12]:
Str[13]:String
Str[14]:String
Str[15]:String
Str[16]:String

但不要期望所有JDK版本都有相同的输出。我看到了一个bug,在某些JDK版本中,第一个空字符串被忽略了。此错误在最新的JDK版本中不存在,但在JDK1.7晚期版本和1.8早期版本之间的某些版本中存在。

这些要求为解释留下了空间。我建议写一个方法,

public final static String[] mySplit(final String s)

其封装了该功能。当然,您可以使用String.split(..),如实现的其他答案中所述。

您应该为输入字符串以及期望的结果和行为编写一些单元测试。

优秀的考生应包括:

 - "0022-3333"
 - "-"
 - "5555-"
 - "-333"
 - "3344-"
 - "--"
 - ""
 - "553535"
 - "333-333-33"
 - "222--222"
 - "222--"
 - "--4555"

通过定义相应的测试结果,您可以指定行为。

例如,如果“-333”应在[,333]中返回,或者如果它是一个错误。“333-333-33”是否可以在[333333-33]或[3333-333,33]中分开,或者这是一个错误?等等

我查看了所有答案,发现所有答案都是第三方许可或基于正则表达式的。

下面是我使用的一个很好的哑实现:

/**
 * Separates a string into pieces using
 * case-sensitive-non-regex-char-separators.
 * <p>
 * &nbsp;&nbsp;<code>separate("12-34", '-') = "12", "34"</code><br>
 * &nbsp;&nbsp;<code>separate("a-b-", '-') = "a", "b", ""</code>
 * <p>
 * When the separator is the first character in the string, the first result is
 * an empty string. When the separator is the last character in the string the
 * last element will be an empty string. One separator after another in the
 * string will create an empty.
 * <p>
 * If no separators are set the source is returned.
 * <p>
 * This method is very fast, but it does not focus on memory-efficiency. The memory
 * consumption is approximately double the size of the string. This method is
 * thread-safe but not synchronized.
 *
 * @param source    The string to split, never <code>null</code>.
 * @param separator The character to use as splitting.
 * @return The mutable array of pieces.
 * @throws NullPointerException When the source or separators are <code>null</code>.
 */
public final static String[] separate(String source, char... separator) throws NullPointerException {
    String[] resultArray = {};
    boolean multiSeparators = separator.length > 1;
    if (!multiSeparators) {
        if (separator.length == 0) {
            return new String[] { source };
        }
    }
    int charIndex = source.length();
    int lastSeparator = source.length();
    while (charIndex-- > -1) {
        if (charIndex < 0 || (multiSeparators ? Arrays.binarySearch(separator, source.charAt(charIndex)) >= 0 : source.charAt(charIndex) == separator[0])) {
            String piece = source.substring(charIndex + 1, lastSeparator);
            lastSeparator = charIndex;
            String[] tmp = new String[resultArray.length + 1];
            System.arraycopy(resultArray, 0, tmp, 1, resultArray.length);
            tmp[0] = piece;
            resultArray = tmp;
        }
    }
    return resultArray;
}

直接处理字符串的另一种方法是将正则表达式与捕获组一起使用。这样做的优点是,它可以直接暗示对输入的更复杂的约束。例如,以下命令将字符串拆分为两部分,并确保两者仅由数字组成:

import java.util.regex.Pattern;
import java.util.regex.Matcher;

class SplitExample
{
    private static Pattern twopart = Pattern.compile("(\\d+)-(\\d+)");

    public static void checkString(String s)
    {
        Matcher m = twopart.matcher(s);
        if (m.matches()) {
            System.out.println(s + " matches; first part is " + m.group(1) +
                               ", second part is " + m.group(2) + ".");
        } else {
            System.out.println(s + " does not match.");
        }
    }

    public static void main(String[] args) {
        checkString("123-4567");
        checkString("foo-bar");
        checkString("123-");
        checkString("-4567");
        checkString("123-4567-890");
    }
}

由于模式在本例中是固定的,因此可以预先编译并存储为静态成员(在示例中是在类加载时初始化的)。正则表达式为:

(\d+)-(\d+)

括号表示捕获组;可以通过Match.group()方法访问与正则表达式的该部分匹配的字符串,如图所示。\d匹配一个十进制数字,+表示“匹配一个或多个前一个表达式)。-没有特殊含义,因此只匹配输入中的字符。请注意,当将其写成Java字符串时,需要对反斜杠进行双转义。其他一些示例:

([A-Z]+)-([A-Z]+)          // Each part consists of only capital letters 
([^-]+)-([^-]+)            // Each part consists of characters other than -
([A-Z]{2})-(\d+)           // The first part is exactly two capital letters,
                           // the second consists of digits