Java 比赛

Java Matcher 类是 Java Regex 包的类之一。 Java Matcher 类和模式是 Regex 包的一部分，它提供了为正则表达式创建类和接口的工具。它有助于找到正则表达式的操作和字符序列，然后与正则表达式的其他字符序列进行比较以匹配。一旦匹配成功，它就会创建一个称为 MatchResult 接口的接口。正则表达式引擎用于执行字符序列匹配和创建界面的定义场景。

开始您的免费软件开发课程

网络开发、编程语言、软件测试及其他

Java 匹配器类方法

下面给出的是类方法：

• 公共布尔匹配()
• 公共布尔查找()
• 公共布尔查找（int start）
• 公共字符串组()
• public int start() 和 int start(int group)
• public int end() 和 int end(int group)
• public int groupCount()
• 公共布尔型lookingAt()
• 公共匹配器appendReplacement()
• public StringBufferappendTail()
• 公共字符串replaceAll()
• 公共字符串replaceFirst()
• public static String quoteReplacement()

1.公共布尔匹配()

boolean matches() 是 Java Matcher 类中的一个方法，用于测试正则表达式是否与模式匹配。

示例：

此程序使用模式说明了 Java Matcher 类的公共 boolean matches() 方法。

代码：

import java.util.regex.*;
public class BooleanRegMatches{
public static void main(String args[])
{
System.out.println(Pattern.matches("[banana]", "qda"));
System.out.println(Pattern.matches("[mango]", "mn"));
System.out.println(Pattern.matches("[orange]", "e"));
}
}

输出：

2.公共布尔查找（）

该方法是匹配器类的一部分，用于查找并匹配下一个表达式，它可以匹配模式并可用于创建接口。

示例：

该程序用于查找并匹配正则表达式，以与模式进行匹配和比较，以创建界面。

代码：

import java.util.regex.Pattern;
import java.util.Scanner;
import java.util.regex.Matcher;
public class Regx_Pattrn_1 {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
while (true) {
System.out.println("consider a regulr exprssn for traversing:");
Pattern pattern_k = Pattern.compile(sc.nextLine());
System.out.println("Next Text to Execute:");
Matcher matcher_g = pattern_k.matcher(sc.nextLine());
boolean found = false;
while (matcher_g.find()) {
System.out.println(" Text needs to be searched  "+matcher_g.group()+" from starting index "+
matcher_g.start()+" and from ending index "+matcher_g.end());
found = true;
}
if(!found){
System.out.println("No match is found after comparison");
}
}
}
}

输出：

3.公共布尔查找（int start）

该方法用于查找从开头或结尾索引开始匹配正则表达式的方法。

示例：

该程序演示了 boolean find(int start) 方法，该方法给出了正则表达式的起始和结束索引。

代码：

import java.util.regex.Pattern;
import java.util.Scanner;
import java.util.regex.Matcher;
public class Java_Pattrn_2 {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
while (true) {
System.out.println("Form one reg_expression pattern:");
Pattern pattern_j = Pattern.compile(sc.nextLine());
System.out.println("Neeed to match some part of the string for execution:");
Matcher matcher_o = pattern_j.matcher(sc.nextLine());
boolean found1 = false;
while (matcher_o.find()) {
System.out.println("got the pattern initiated where "+matcher_o.group()+" index_is_starting "+
matcher_o.start()+" index_is_ending "+matcher_o.end());
found1 = true;
}
if(!found1){
System.out.println("Some kind of mismatch is prevailing");
}
}
}
}

输出：

4.公共字符串组()

此方法是 Java Matcher 类的一部分，该类随后返回正则表达式的匹配字符串。

示例：

该程序演示了 Java Matcher 类的 String group() 方法，该方法尝试在命中匹配字符串后生成正则表达式的后续子字符串。

代码：

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Regx_Pttrn_3 {
public static void main(String[] args) {
String reg_exprn_txt ="I am trying to learn something new, and trying to learning something from there," +
" and will one day become a skilled person. ";
String pattern_one_str = "(trying)";
Pattern pattrn_7 = Pattern.compile(pattern_one_str);
Matcher matchr_0 = pattrn_7.matcher(reg_exprn_txt);
while(matchr_0.find()) {
System.out.println(" Matched_Value: " + matchr_0.group(1));
}
}
}

输出：

5. public int start() 和 int start(int group)

int start() 和 int start(int group) 方法作为 Java Matcher 类的一部分，用于获取以分组字符串的起始索引为起始索引的字符串的子字符串的后续值。

示例：

该程序演示了字符串分组，然后查找后续匹配器字符串以匹配正则表达式的起始索引。

代码：

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Regx_Pttrn4 {
public static void main(String[] args) {
String reg_txt_exprssion    =
"This text needs to be done " +
"with some careful attention 'done'.";
String string_grouping = "done";
Pattern pattern_l = Pattern.compile(string_grouping);
Matcher matcher_l = pattern_l.matcher(reg_txt_exprssion);
int count = 0;
while(matcher_l.find()) {
count++;
System.out.println("Matching_context: " + count + " : "
+ matcher_l.start());
}
}
}

输出：

6. public int end() 和 int end(in group)

此方法用于返回匹配的后续字符串模式的子字符串的结束索引。

示例：

该程序用于演示Java Matcher类的int end（in group）方法。

代码：

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Regx_Pattrn5 {
public static void main(String[] args) {
String Expression    =
"Some special substring characters and escape characters need to be searched for. " +
"that to get the number of hits on the given expression of the text 'to'.";
String string_Pattrn = "to";
Pattern pattern_f = Pattern.compile(string_Pattrn);
Matcher matcher_f = pattern_f.matcher(Expression);
int count = 0;
while(matcher_f.find()) {
count++;
System.out.println("match_found: " + count + " : "
+ matcher_f.end());
}
}
}

输出：

7.公共 int groupCount

此方法用于在比较正则表达式的匹配子字符串后返回作为一组正则表达式出现的组的计数。

示例：

该程序演示了 Java Matcher 类的 int 组计数方法。

代码：

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Regx_Pattrn_6 {
public static void main(String[] args) {
String run_Exp  = " I am fond of eating delicious and yummy food everythime, and my mom is also fond of cooking that," +
" and dad also wants to taste the yummy food.";
String patternString1 = "(fond) (.+?) ";
Pattern pattern_s = Pattern.compile(patternString1);
Matcher matcher_s = pattern_s.matcher(run_Exp);
while(matcher_s.find()) {
System.out.println("matching_found_present: " +  "count:"+ matcher_s.group(1) +
" "       + matcher_s.group(2));
}
}
}

输出：

8. public boolean lookingat()

As part of the matcher class, this method only tries to match the beginning of the text, not the entire text, which means, unlike the matcher class, which considers the entire regular expression for matching and result.

Example:

This program demonstrates the boolean lookingat() method of the Java Matcher class.

Code:

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Regx_Pattrn_7 {
public static void main(String[] args) {
String String_expr = "An expression to search and match the string pattern " + "make a search for the pattern.";
String String_ptrn = "pattern";
Pattern pattern_k = Pattern.compile(String_ptrn, Pattern.CASE_INSENSITIVE);
Matcher matcher_k = pattern_k.matcher(String_expr);
System.out.println("currently_looking_At = " + matcher_k.lookingAt());
System.out.println("currently_matches   = " + matcher_k.matches());
}
}

Output:

9. public Matcher appendReplacement()

This method is used to replace the set of text in the regular expression and then append that input string into the string buffer. It keeps a check on the string buffer what is being copied and what is needed to be replaced.

Example:

This program demonstrates the Matcher appendReplacement() method of Java Matcher.

Code:

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Regex_Pttrn_8 {
public static void main(String[] args) {
String sm_txt  =  "I love to read books of harry potter, and i also love to read books of JK Rowling" +   " and My favourite writer writes all fiction books.";
String String_ptrn1 = "((books) (.+?)) ";
Pattern pattern_o = Pattern.compile(String_ptrn1);
Matcher matcher_o = pattern_o.matcher(sm_txt);
StringBuffer stringBuffer = new StringBuffer();
while(matcher_o.find()){
matcher_o.appendReplacement(stringBuffer, " fiction books ");
System.out.println(stringBuffer.toString());
}
}
}

Output:

10. public StringBuffer appendTail()

This method also behaves in a similar fashion with a difference that if the last match is found from the input text and is not yet copied to the string buffer, then it is needed to check for the required text and can append at the end of the expression and then can be copied into the buffer.

Example:

This program demonstrates the StringBuffer append Tail() method of Java Matcher.

Code:

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Regex_Pttrn_8 {
public static void main(String[] args) {
String sm_txt  =  "I love to read books of harry potter, and i also love to read books of JK Rowling" +  " and My favourite writer writes all fiction books.";
String String_ptrn1 = "((books) (.+?)) ";
Pattern pattern_p = Pattern.compile(String_ptrn1);
Matcher matcher_p = pattern_p.matcher(sm_txt);
StringBuffer stringBuffer = new StringBuffer();
while(matcher_p.find()){
matcher_p.appendReplacement(stringBuffer, " fiction books ");
System.out.println(stringBuffer.toString());
}
matcher_p.appendTail(stringBuffer);
System.out.println(stringBuffer.toString());
}
}

Output:

11. public String replaceAll()

As its name suggests, the String replaceAll () method can replace all the found matches and matched groups with the regular expression.

Example:

This program demonstrates the String replaceAll() method of Java Matcher.

Code:

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Java_Reg_Replace {
public static void main(String[] args) {
String one_ptrn    ="I want to have a cup of tea, and I also want to have a cup of coffe at the same time," +
" and also want to have toffee.";
String ptrn_ex_strng = "((cofee) (.+?)) ";
Pattern pattern1 = Pattern.compile(ptrn_ex_strng);
Matcher matcherb = pattern1.matcher(one_ptrn);
String replaceAll = matcherb.replaceAll("tea or coffee ");
System.out.println("replaceAll   = " + replaceAll);
}
}

Output:

12. public String replaceFirst()

This method is used for replacing the string text from the beginning of the regular expression as soon as the first match gets hit.

Example:

This program demonstrates the replaceFirst() method of Java Matcher.

Code:

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class Java_Reg_Replace {
public static void main(String[] args) {
String one_ptrn    ="I want to have a cup of tea, and I also want to have a cup of coffe at the same time," + " and also want to have toffee.";
String ptrn_ex_strng = "((cofee) (.+?)) ";
Pattern pattern1 = Pattern.compile(ptrn_ex_strng);
Matcher matcherb = pattern1.matcher(one_ptrn);
String replaceAll = matcherb.replaceAll("tea or coffee ");
System.out.println("replaceAll   = " + replaceAll);
String replaceFirst = matcherb.replaceFirst("tea or coffee ");
System.out.println("replaceFirst = " + replaceFirst);
}
}

Output:

13. public static String quoteReplacement()

It is a mediator method of all the replace methods and is used when the string and the characters in the string need to be replaced with the parameters passed as a replaced parameter.

Example:

This program demonstrates the String quoteReplacement() method of Java Matcher.

Code:

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class reg_quote_replcment {
public static void main(String[] args) {
String reg_exprsn = "Welcome Everyone";
Pattern pattern_a = Pattern.compile(reg_exprsn);
String stringNeedsToMatch  = "Welcome evryone to the laerning portal of educba";
Matcher matcher_b = pattern_a.matcher(stringNeedsToMatch);
String stringToBeReplaced = "Welcome";
System.out.println(matcher_b .quoteReplacement(stringToBeReplaced));
}
}

Output:

Conclusion

Java Matcher class is a class which is part of Java regex package and mainly deals with the regular expressions and its functioning with the other regular function at the index level, replacement methods and quotereplacement method. It has simplified the overall manipulation of the strings and characters of the string for regular expressions.

以上是Java 比赛的详细内容。更多信息请关注PHP中文网其他相关文章！