How to use the join() function of the String class in Java to concatenate multiple strings into one string

How to use the join() function of the String class in Java to splice multiple strings into one string

In Java, the String class is a commonly used class used to represent strings. It provides many methods for manipulating strings, one of the important methods is the join() function. This function can concatenate multiple strings into one string, and you can specify a delimiter to separate each string. This article will introduce how to use the join() function to implement string splicing operations.

Using String's join() function is very simple. You only need to call the function and pass in the delimiter and the string to be spliced ​​as parameters. The following is a sample code using the join() function:

public class StringJoinExample {
    public static void main(String[] args) {
        String[] words = {"Hello", "World", "Java"};
        String result = String.join(" ", words);
        System.out.println(result);
    }
}

In the above code, we first created a string array words, which contains three strings "Hello", "World" and "Java". Then, we called the join() function of the String class and passed in a space as the separator and the string array words as parameters. Finally, the returned splicing result is assigned to the result variable and the result is printed.

Run the above code, the output result is: "Hello World Java". As you can see, you can use the join() function to concatenate multiple strings into one string and separate them using the specified delimiter.

In addition to regular string arrays, String's join() function can also accept other types of parameters, such as List, Set, Stream, etc. The following is a sample code using List parameters:

import java.util.Arrays;
import java.util.List;

public class StringJoinExample {
    public static void main(String[] args) {
        List<String> words = Arrays.asList("Hello", "World", "Java");
        String result = String.join(" ", words);
        System.out.println(result);
    }
}

In the above code, we use List to store strings and pass the List to the join() function for splicing operation. The other parts are the same as the previous sample code.

In addition to string arrays and Lists, String's join() function can also accept any other number of parameters, such as:

public class StringJoinExample {
    public static void main(String[] args) {
        String result = String.join(" ", "Hello", "World", "Java");
        System.out.println(result);
    }
}

In the above code, we directly use multiple strings as The parameters are passed to the join() function, and the other parts are the same as the previous example code.

It should be noted that when using the join() function, the parameter type passed in must be a subclass of CharSequence, because the parameter type of the join() function is a serializable character sequence. Common subclasses include String, StringBuilder, StringBuffer, etc.

To summarize, you can use String's join() function to concatenate multiple strings into one string and separate them using the specified delimiter. Just pass in a delimiter and the string parameters to be spliced. Whether it is a string array, List or any other number of parameters, they can be spliced ​​through the join() function.

I hope this article will be helpful to understand and use the join() function of the String class, and can be used flexibly in actual development.

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