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    <p>There really isn't a good answer. An iterator in Java specifically applies to a collection of discrete items (objects). You would think that a <code>String</code>, which implements <code>CharSequence</code>, should be a "collection" of discrete characters. Instead, it is treated as a single entity that happens to consist of characters. </p> <p>In Java, it seems that iterators are only really applied to collections and not to a string. There is no reason why it is this way (near as I can tell - you would probably have to talk to Gosling or the API writers); it appears to be convention or a design decision. Indeed, there is nothing <em>preventing</em> <code>CharSequence</code> from implementing <code>Iterable</code>. </p> <p>That said, you can iterate over the characters in a string like so:</p> <pre><code>for (int i = 0; i &lt; str.length(); i++) { System.out.println(str.charAt(i)); } </code></pre> <p>Or:</p> <pre><code>for(char c : str.toCharArray()) { System.out.println(c); } </code></pre> <p>Or:</p> <pre><code>"Java 8".chars().forEach(System.out::println); </code></pre> <p>Also note that you cannot modify a character of a String in place because Strings are immutable. The mutable companion to a String is StringBuilder (or the older StringBuffer).</p> <p><strong>EDIT</strong></p> <p>To clarify based on the comments on this answer. I'm trying to explain <em>a possible rationale</em> as to why there is no Iterator on a <code>String</code>. I'm not trying to say that it's not possible; indeed I think it would make sense for <code>CharSequence</code> to implement <code>Iterable</code>.</p> <p><code>String</code> provides <code>CharSequence</code>, which, if only conceptually, is different from a <code>String</code>. A <code>String</code> is usually thought of as a single entity, whereas <code>CharSequence</code> is exactly that: a sequence of characters. It would make sense to have an iterator on a sequence of characters (i.e., on <code>CharSequence</code>), but not simply on a <code>String</code> itself.</p> <p>As Foxfire has rightly pointed out in the comments, <code>String</code> implements the <code>CharSequence</code> interface, so type-wise, a <code>String</code> is a <code>CharSequence</code>. Semantically, it seems to me that they are two separate things - I'm probably being pedantic here, but when I think of a <code>String</code> I usually think of it as a single entity that happens to consist of characters. Consider the difference between the sequence of digits <code>1, 2, 3, 4</code> and the number <code>1234</code>. Now consider the difference between the string <code>abcd</code> and the sequence of characters <code>a, b, c, d</code>. I'm trying to point out this difference. </p> <p>In my opinion, asking why <code>String</code> doesn't have an iterator is like asking why <code>Integer</code> doesn't have an iterator so that you can iterate over the individual digits.</p>
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    1. POWhy doesn't the String class in Java implement Iterable?
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    1. USMartin Andersson
    1. USVivin Paliath
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    1. COSurely treating a string as a collection of letters isn't entirely without precedent, and to argue it on a "makes sense" case seems a little spurious.
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    2. CO@Svend that's true - I was actually at a loss for words - I think I wanted to say "it doesn't make sense in some cases" or even "it doesn't make sense in most cases" considering what iterators really are. I will edit my answer.
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    3. CO"A String is not really a "collection" of discrete characters.". Well it is. In fact it even implements CharSequence, which is exactly that: An orderd collection of discrete characters!
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      1. USFoxfire
 

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