Top 10 Methods for Java Arrays
The following are top 10 methods for Java Array. They are the most voted questions from stackoverflow.
0. Declare an array
String[] aArray = new String[5]; String[] bArray = {"a","b","c", "d", "e"}; String[] cArray = new String[]{"a","b","c","d","e"}; |
1. Print an array in Java
int[] intArray = { 1, 2, 3, 4, 5 }; String intArrayString = Arrays.toString(intArray); // print directly will print reference value System.out.println(intArray); // [[email protected] System.out.println(intArrayString); // [1, 2, 3, 4, 5] |
2. Create an ArrayList from an array
String[] stringArray = { "a", "b", "c", "d", "e" }; ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(stringArray)); System.out.println(arrayList); // [a, b, c, d, e] |
3. Check if an array contains a certain value
String[] stringArray = { "a", "b", "c", "d", "e" }; boolean b = Arrays.asList(stringArray).contains("a"); System.out.println(b); // true |
4. Concatenate two arrays
int[] intArray = { 1, 2, 3, 4, 5 }; int[] intArray2 = { 6, 7, 8, 9, 10 }; // Apache Commons Lang library int[] combinedIntArray = ArrayUtils.addAll(intArray, intArray2); |
5. Declare an array inline
method(new String[]{"a", "b", "c", "d", "e"}); |
6. Joins the elements of the provided array into a single String
// containing the provided list of elements // Apache common lang String j = StringUtils.join(new String[] { "a", "b", "c" }, ", "); System.out.println(j); // a, b, c |
7. Covnert an ArrayList to an array
String[] stringArray = { "a", "b", "c", "d", "e" }; ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(stringArray)); String[] stringArr = new String[arrayList.size()]; arrayList.toArray(stringArr); for (String s : stringArr) System.out.println(s); |
8. Convert an array to a set
Set<String> set = new HashSet<String>(Arrays.asList(stringArray)); System.out.println(set); //[d, e, b, c, a] |
9. Reverse an array
int[] intArray = { 1, 2, 3, 4, 5 }; ArrayUtils.reverse(intArray); System.out.println(Arrays.toString(intArray)); //[5, 4, 3, 2, 1] |
10. Remove element of an array
int[] intArray = { 1, 2, 3, 4, 5 }; int[] removed = ArrayUtils.removeElement(intArray, 3);//create a new array System.out.println(Arrays.toString(removed)); |
One more - convert int to byte array
byte[] bytes = ByteBuffer.allocate(4).putInt(8).array(); for (byte t : bytes) { System.out.format("0x%x ", t); } |
<pre><code> String foo = "bar"; </code></pre>
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Superb 😉
I loved it a lot.
that was good but this will also be helpful : kodingexamples.blogspot.com/2014/04/how-to-reverse-string-in-java.html
These are good, but what about int array instead of String?? (3.)
You can find the more details and the Example program here,
http://javadomain.in/converting-string-array-integer-array-example-java/
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This is a good point. (3.) does not work for int type. “the problem lies in the interpretation of the varargs method Arrays.asList. It interprets the type to be int[], so that you receive back a List, not a List. So none of the numbers you pass in will be equal to an int[].”http://stackoverflow.com/questions/21197930/arrays-aslistan-array-containsan-integer-always-false-why
УОТ ТАК УОТ
this is good post and help me more to understand java array. must visit java array program examples
BTW, there is an “obvious” typo.:
7. Covnert
should be “Convert”
It’s not a big deal to me. The rest of the article was helpful. Thanks.
BTW, there is an “obvious” typo.:
7. Covnert
should be “Convert”
I’m unable to compile and run “ArrayUtils.reverse(intArray);”
You have to use: import org.apache.commons.lang3.ArrayUtils;
get cacner nigag XDXD