《Java数组》常用方法

小咪咪 2023-10-04 08:34 3阅读 0赞

##### 1.声明一个数组 #####

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

##### 2.打印一个数组 #####

int[] a = { 1, 2, 3, 4, 5 };
    String intArrayString = Arrays.toString(a);
    System.out.println(a);
    // [I@7150bd4d
    System.out.println(intArrayString);
    // [1, 2, 3, 4, 5]

##### 3.根据数组创建ArrayList #####

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.判断数组内部是否包含某个值 #####

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.ArrayList转数组 #####

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);

##### 7.Array转Set #####

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

##### 8.反转数组 #####

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

##### 9.删除数组元素 #####

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

##### 10.整形转字节数组 #####

byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
    for (byte t : bytes) {
        System.out.format("0x%x ", t);
    }