Java Pattern pattern()用法及代碼示例

Java中Pattern類的pattern()方法用於獲取正則表達式，將其編譯以創建此模式。我們使用正則表達式創建模式，並且使用此方法來獲取相同的源表達式。

用法:

public String pattern()

參數：此方法不接受任何內容作為參數。

返回值：此方法返回模式的源正則表達式。

以下示例程序旨在說明pattern()方法：
示例1:

// Java program to demonstrate 
// Pattern.pattern() method 
  
import java.util.regex.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create a REGEX String 
        String REGEX = "(.*)(for)(.*)?"; 
  
        // create the string 
        // in which you want to search 
        String actualString 
            = "code of Machine"; 
  
        // create pattern 
        Pattern pattern1 = Pattern.compile(REGEX); 
  
        // find the regular expressio of pattern 
        String RegularExpression = pattern1.pattern(); 
  
        System.out.println("Pattern's RegularExpression = "
                           + RegularExpression); 
    } 
}

輸出：

Pattern's RegularExpression = (.*)(for)(.*)?

示例2:

// Java program to demonstrate 
// Pattern.compile method 
  
import java.util.regex.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create a REGEX String 
        String REGEX = "(.*)(ee)(.*)?"; 
  
        // create the string 
        // in which you want to search 
        String actualString 
            = "geeks"; 
  
        // create pattern 
        Pattern pattern1 = Pattern.compile(REGEX); 
  
        // find the regular expressio of pattern 
        String RegularExpression = pattern1.pattern(); 
  
        System.out.println("Pattern's RegularExpression = "
                           + RegularExpression); 
    } 
}

輸出：

Pattern's RegularExpression = (.*)(ee)(.*)?

參考文獻：
https://docs.oracle.com/javase/10/docs/api/java/util/regex/Pattern.html#pattern()

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