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  • Top 10 Methods for Java Arrays

    作者:X Wang

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

    转载文章,转载请注明作者和出处

    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);
    // [I@7150bd4d
     
    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);
    }
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  • 原文地址:https://www.cnblogs.com/lonkiss/p/3722040.html
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