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  • Java StringJoiner

    Java StringJoiner

    Java added a new final class StringJoiner in java.util package. It is used to construct a sequence of characters separated by a delimiter. Now, you can create string by passing delimiters like comma(,), hyphen(-) etc. You can also pass prefix and suffix to the char sequence.

    import java.util.StringJoiner;
    
    public class StringJoinerExample {
        public static void main(String[] args) {
            // passing comma(,) as delimiter
            StringJoiner joinNames = new StringJoiner(",");
            // Adding values to StringJoiner
            joinNames.add("Rahul");
            joinNames.add("Raju");
            joinNames.add("Peter");
            joinNames.add("Raheem");
            System.out.println(joinNames);
    
            // passing comma(,) and square-brackets as delimiter
            StringJoiner joinNames2 = new StringJoiner(",", "[", "]");
            // Adding values to StringJoiner
            joinNames2.add("Rahul");
            joinNames2.add("Raju");
            joinNames2.add("Peter");
            joinNames2.add("Raheem");
            System.out.println(joinNames2);
    
            StringJoiner joinNames3 = new StringJoiner(",", "[", "]");
            joinNames3.add("Rahul");
            joinNames3.add("Raju");
    
            StringJoiner joinNames4 = new StringJoiner(":", "[", "]");
            joinNames4.add("Peter");
            joinNames4.add("Raheem");
    
            // Merging two StringJoiner
            StringJoiner merge = joinNames3.merge(joinNames4);
            System.out.println(merge);
        }
    }
    

    点击查看结果

    ``` Rahul,Raju,Peter,Raheem [Rahul,Raju,Peter,Raheem] [Rahul,Raju,Peter:Raheem] ```
    import java.util.StringJoiner;
    
    public class StringJoinerMethodExample {
        public static void main(String[] args) {
            StringJoiner joinNames = new StringJoiner(",");
    
            // Prints nothing because it is empty
            System.out.println(joinNames);
    
            // We can set default empty value.
            joinNames.setEmptyValue("It is empty");
            System.out.println(joinNames);
    
            // Adding values to StringJoiner
            joinNames.add("Rahul");
            joinNames.add("Raju");
            System.out.println(joinNames);
    
            // Returns length of StringJoiner
            int length = joinNames.length();
            System.out.println("Length: " + length);
    
            // Returns StringJoiner as String type
            String str = joinNames.toString();
            System.out.println(str);
    
            // Now, we can apply String methods on it
            char ch = str.charAt(3);
            System.out.println("Character at index 3: " + ch);
    
            // Adding one more element
            joinNames.add("Sorabh");
            System.out.println(joinNames);
    
            // Returns length
            int newLength = joinNames.length();
            System.out.println("New Length: " + newLength);
        }
    }
    

    点击查看结果

    ```

    It is empty
    Rahul,Raju
    Length: 10
    Rahul,Raju
    Character at index 3: u
    Rahul,Raju,Sorabh
    New Length: 17

    </div>
    
    **参考资料**
    * [https://www.javatpoint.com/java-stringjoiner](https://www.javatpoint.com/java-stringjoiner)
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  • 原文地址:https://www.cnblogs.com/hgnulb/p/10095770.html
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