Top 10 Methods for Java Arrays

http://www.programcreek.com/2013/09/top-10-methods-for-java-arrays/

0. Declare an array

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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



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int[] intArray = { 1, 2, 3, 4, 5 };

String intArrayString = Arrays.toString(intArray);



// print directly will print reference value

System.out.println(intArray);

// [I@7150bd4d



System.out.println(intArrayString);

// [1, 2, 3, 4, 5]

2. Create an ArrayList from an array

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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

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String[] stringArray = { "a", "b", "c", "d", "e" };

boolean b = Arrays.asList(stringArray).contains("a");

System.out.println(b);

// true



4. Concatenate two arrays

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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

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method(new String[]{"a", "b", "c", "d", "e"});



6. Joins the elements of the provided array into a single String

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// 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

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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

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Set<String> set = new HashSet<String>(Arrays.asList(stringArray));

System.out.println(set);

//[d, e, b, c, a]



9. Reverse an array

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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

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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

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byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();



for (byte t : bytes) {

System.out.format("0x%x ", t);