CharMatcher 类|番石榴|爪哇

原文:https://www.geeksforgeeks.org/charmatcher-class-guava-java/

CharMatcher 为任何 Java 字符值确定一个真或假值。这个类提供了各种方法来处理各种 Java 类型的字符值。

申报:对的申报为:

@GwtCompatible(emulated = true)
public final class CharMatcher
   extends Object

有 2 种方法可以获得 CharMatcher 实例:

  • Using constants: CharMatcher class provides following constants to obtain CharMatcher instance.

    注意:这个类只处理字符值。它不理解 0x10000 到 0x10FFFF 范围内的补充 Unicode 代码点。这样的逻辑字符使用代理项对被编码到一个字符串中，CharMatcher 将这些字符视为两个独立的字符。

  • 使用 CharMatcher 类提供的方法:可以使用以下方法获取 CharMatcher 类的实例。 T3】

例 1:

// Java code to get number of matching
// characters in given sequence
// and display them using countIn()

import com.google.common.base.CharMatcher;

class GFG {

    // Driver code
    public static void main(String args[])
    {

        // "anyOf" method returns a char matcher
        // that matches any character present in
        // the given character sequence.
        CharMatcher matcher = CharMatcher.anyOf("aeiou");

        String str = "Hello GeeksforGeeks, What's up ?";

        // "countIn" returns the number of matching
        // characters found in a character sequence.
        int vowels = matcher.countIn(str);

        // To display the number of vowels in
        // character sequence
        System.out.println("Number of vowels in '"
                           + str + "' are "
                           + vowels);
    }
}

Output:

Number of vowels in 'Hello GeeksforGeeks, What's up ?' are 9

CharMatcher 类的其他一些方法有:

例 2:

// Java code to get the index
// of matching character

import com.google.common.base.CharMatcher;

class GFG {

    // Driver code
    public static void main(String args[])
    {

        // "anyOf" method returns a char matcher
        // that matches any character present in
        // the given character sequence.
        CharMatcher matcher = CharMatcher.anyOf("aeiou");

        String str = "Hello GeeksforGeeks, What's up ?";

        // To return the index of first matching
        // character in given input sequence.
        int firstIndex = matcher.indexIn(str);

        // To Return the index of first matching
        // character in given input sequence,
        // from given starting index.
        int nextIndex = matcher.indexIn(str, firstIndex + 1);

        // To return the index of the last matching
        // character in a character sequence
        int lastIndex = matcher.lastIndexIn(str);

        System.out.println("First Index is " + firstIndex);
        System.out.println("Next Index is " + nextIndex);
        System.out.println("Last Index is " + lastIndex);
    }
}

Output:

First Index is 1
Next Index is 4
Last Index is 28

CharMatcher 类的其他一些方法有:

例 3:

// Java code to remove all digits 
// from a  given string

import com.google.common.base.CharMatcher;

class GFG {

    // Driver code
    public static void main(String args[])
    {

        // Determines whether a character is
        // a digit according to Unicode.
        CharMatcher matcher = CharMatcher.DIGIT;

        String str = "12345Hello GeeksforGeeks1287 What's 9886up";
        System.out.println("Original String : " + str);

        // To remove all matching characters
        // from given string.
        String result = matcher.removeFrom(str);

        // To display the string which
        // doesn't contain digit
        System.out.println("After digit removal : " + result);
    }
}

Output:

Original String : 12345Hello GeeksforGeeks1287 What's 9886up
After digit removal : Hello GeeksforGeeks What's up

参考:T2】谷歌番石榴

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