10 commonly used methods for java arrays

Create an array:

String[] a = new String[5]; String[] b = {“a”,”b”,”c”, “d”, “e”}; String[] c = new String[]{“a”,”b”,”c”,”d”,”e”};

1. Print the array

We often use for loops or some iterators to print out all elements of the array. But we can also change the posture.

int array[] = {1,2,3,4,5}; System.out.println(array); //[I@1234be4e String arrStr = Arrays.toString(array); System.out.println(array); //[1,2,3,4,5];

2. Create ArrayList

String[] array = { “a”, “b”, “c”, “d”, “e” }; ArrayList arrayList = new ArrayList(Arrays.asList(array)); System.out.println(arrayList); // [a, b, c, d, e]

3. Check whether it contains a certain value

int array[] = {1,2,3,4,5}; boolean isContain= Arrays.asList(array).contains(5); System.out.println(isContain); // true

4. Connect two arrays

int[] array1 = { 1, 2, 3, 4, 5 }; int[] array2 = { 6, 7, 8, 9, 10 }; // Apache Commons Lang library int[] combinedIntArray = ArrayUtils.addAll(array1, array2);

5. In one line Declare an array

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

6, invert the array

int[] intArray = { 1, 2, 3, 4, 5 }; // Apache Commons Lang library ArrayUtils.reverse(intArray); System.out.println(Arrays.toString(intArray)); //[5, 4, 3, 2, 1]

7, delete an element

int[] intArray = { 1, 2, 3, 4, 5 }; int[] removed = ArrayUtils.removeElement(intArray, 3);//create a new array System.out.println(Arrays.toString(removed));

8, convert it to set

Set set = new HashSet(Arrays.asList(new String[]{"a", "b", "c", "d", "e"})); System.out.println(set); //[d, e, b, c, a]

9, convert Array Convert List to Array

String[] stringArray = { "a", "b", "c", "d", "e" }; ArrayList arrayList = new ArrayList(Arrays.asList(stringArray)); String[] stringArr = new String[arrayList.size()]; arrayList.toArray(stringArr);

10. Compose array elements into a string

// Apache common lang String j = StringUtils.join(new String[] { "a", "b", "c" }, ", "); System.out.println(j); //a, b, c

For more related knowledge, please pay attention tojava basic tutorialcolumn

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