Hello, Adventurer! Today, we will learn about splitting and joining strings — two vital operations for processing textual data in Java. Are you ready? Let's start this journey!

In Java, the split() method divides a string into several substrings based on a delimiter — a character that separates words. It stores these substrings into an array. Here's an example to clarify:

Java
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1// Our original sentence
2String sentence = "I love programming.";
3
4// Let's split it into individual words
5String[] words = sentence.split(" "); // Now words = ["I", "love", "programming."]
6System.out.println(Arrays.toString(words)); // [I, love, programming.]

In this snippet, we have a sentence that we divide into separate words using the split() method with a space as the delimiter. The results are stored in the array words.

The join() method merges an array of strings back into a single string using a specified delimiter. It is the reverse of the split() method. Here's how it works:

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1// Our original words
2String[] words = {"programming", "I" "love"};
3
4// Let's join the words into a new sentence
5String sentence = String.join(" ", words);
6
7// Now "sentence" is "programming I love"

In the example above, we took an array of words and combined them into a single string, using a space as the delimiter.

You can combine split() and join() to rearrange sentences. For instance, let's take "I love programming" and rearrange it to "programming love I":

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1String sentence = "I love programming.";
2
3// Split the sentence into words
4String[] words = sentence.split(" ");
5
6// Swap the first and third words
7String tempWord = words[0];
8words[0] = words[2];
9words[2] = tempWord;
10
11// The `words` is ["programming", "love", "I"] now
12
13// Join the words back into a sentence
14String newSentence = String.join(" ", words);
15
16System.out.println(newSentence); // Output: "programming love I"

In this example, we first split the sentence into words. Next, we swapped the first and last words, and, finally, we joined them back into a new sentence.

In fact, String.join is so flexible that it even allows to specify all parts to join one by one:

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1System.out.println(String.join(" ", "See", "how", "you", "can", "join", "any", "number", "of", "words!"));
2// Output: See how you can join any number of words!

It's very useful at times!

Great job, Explorer! You've learned how to split and join strings in Java using split() and join(). Now, you will try your hand at some exercises to reinforce your newly acquired skills. Are you ready to explore further? Let's proceed!