You can do an enhanced for loop (for java 5 and higher) for iteration on array's elements:
String[] elements = {"a", "a", "a", "a"};
for (String s: elements) {
//Do your stuff here
System.out.println(s);
}
You can do an enhanced for loop (for java 5 and higher) for iteration on array's elements:
String[] elements = {"a", "a", "a", "a"};
for (String s: elements) {
//Do your stuff here
System.out.println(s);
}
String[] elements = { "a", "a", "a", "a" };
for( int i = 0; i < elements.length - 1; i++)
{
String element = elements[i];
String nextElement = elements[i+1];
}
Note that in this case, elements.length is 4, so you want to iterate from [0,2] to get elements 0,1, 1,2 and 2,3.
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for (Iterator<String> i = someIterable.iterator(); i.hasNext();) {
String item = i.next();
System.out.println(item);
}
Note that if you need to use i.remove(); in your loop, or access the actual iterator in some way, you cannot use the for ( : ) idiom, since the actual iterator is merely inferred.
As was noted by Denis Bueno, this code works for any object that implements the Iterable interface.
If the right-hand side of the for (:) idiom is an array rather than an Iterable object, the internal code uses an int index counter and checks against array.length instead. See the Java Language Specification.
for (int i = 0; i < someArray.length; i++) {
String item = someArray[i];
System.out.println(item);
}
The construct for each is also valid for arrays. e.g.
String[] fruits = new String[] { "Orange", "Apple", "Pear", "Strawberry" };
for (String fruit : fruits) {
// fruit is an element of the `fruits` array.
}
which is essentially equivalent of
for (int i = 0; i < fruits.length; i++) {
String fruit = fruits[i];
// fruit is an element of the `fruits` array.
}
So, overall summary:
[nsayer] The following is the longer form of what is happening:
for(Iterator<String> i = someList.iterator(); i.hasNext(); ) { String item = i.next(); System.out.println(item); }Note that if you need to use i.remove(); in your loop, or access the actual iterator in some way, you cannot use the for( : ) idiom, since the actual Iterator is merely inferred.
[Denis Bueno]
It's implied by nsayer's answer, but it's worth noting that the OP's for(..) syntax will work when "someList" is anything that implements java.lang.Iterable -- it doesn't have to be a list, or some collection from java.util. Even your own types, therefore, can be used with this syntax.
The easiest way to for-each every char in a String is to use toCharArray():
for (char ch: "xyz".toCharArray()) {
}
This gives you the conciseness of for-each construct, but unfortunately String (which is immutable) must perform a defensive copy to generate the char[] (which is mutable), so there is some cost penalty.
From the documentation:
[
toCharArray()returns] a newly allocated character array whose length is the length of this string and whose contents are initialized to contain the character sequence represented by this string.
There are more verbose ways of iterating over characters in an array (regular for loop, CharacterIterator, etc) but if you're willing to pay the cost toCharArray() for-each is the most concise.
String s = "xyz";
for(int i = 0; i < s.length(); i++)
{
char c = s.charAt(i);
}