Java 数组的 12 个最佳方法

1.  声明一个数组

    String[] aArray = new String[5];
    String[] bArray = {"a","b","c", "d", "e"};
    String[] cArray = new String[]{"a","b","c","d","e"};  

2.  输出一个数组

    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]  

3.  从一个数组创建数组列表

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]

4.  检查一个数组是否包含某个值

    String[] stringArray = { "a", "b", "c", "d", "e" };
    boolean b = Arrays.asList(stringArray).contains("a");
    System.out.println(b);
    // true  

5.  连接两个数组

    int[] intArray = { 1, 2, 3, 4, 5 };
    int[] intArray2 = { 6, 7, 8, 9, 10 };
    // Apache Commons Lang library
    int[] combinedIntArray = ArrayUtils.addAll(intArray, intArray2);  

6.  声明一个内联数组（Array inline）

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

7.  把提供的数组元素放入一个字符串

    // 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  

8.  将一个数组列表转换为数组

    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);  

9.  将一个数组转换为集（set）

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

10.  逆向一个数组

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

11.  移除数组中的元素

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

12.  将整数转换为字节数组

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

    for (byte t : bytes) {
       System.out.format("0x%x ", t);
    }