java Arrays工具类常用十大方法

Arrays工具类十大常用方法

 

0. 声明数组

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

1. 打印数组

int[] intArray = { 1, 2, 3, 4, 5 };  
    String intArrayString = Arrays.toString(intArray);  

    // 直接打印,则会打印出引用对象的Hash值  
    // [I@7150bd4d  
    System.out.println(intArray);  

    // [1, 2, 3, 4, 5]  
    System.out.println(intArrayString);

2. 根据数组创建ArrayList

String[] stringArray = { "a", "b", "c", "d", "e" };  
    ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(stringArray));  
    // [a, b, c, d, e]  
    System.out.println(arrayList);

3. 检查数组是否包含某个值

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

4. 合并连接两个数组

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

5. 声明内联数组

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

6. 用给定的字符串连结(join)数组

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

7. 将ArrayList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);

8. 将数组转换为Set

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

9. 数组元素反转

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

10. 移除元素

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

更多——转换int值为字节数组

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

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