Java中数组常用方法简介说明

声明数组

String[] aArray = new String[5];
String[] bArray = {"java265-1","java265-2","java265-3", "java265-4", "java265-5"};
String[] cArray = new String[]{"java265-1","java265-2","java265-3", "java265-4", "java265-5"};

打印数组

int[] intArray = { 88,99,110,222,333 };
String intArrayString = Arrays.toString(intArray);

System.out.println(intArray);
//打印数组地址

System.out.println(intArrayString);
// [88,99,110,222,333]

从数组创建一个 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]

检查数组是否包含某一个值

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

合并数组

int[] intArray = { 88,99,110,222,333 };
int[] intArray2 = { 6, 7, 8, 9, 10 };
// Apache Commons Lang library
int[] combinedIntArray = ArrayUtils.addAll(intArray, intArray2);

一行代码声明数组

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

将数组中的元素使用的分隔符连接起来

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

将一个 ArrayList 转换成数组

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);

将一个数组转换成Set

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

反转数组

int[] intArray = { 88,99,110,222,333 };
ArrayUtils.reverse(intArray);
System.out.println(Arrays.toString(intArray));
//[333,222,110,99,88]

移除数组中的元素

int[] intArray = { 88,99,110,222,333 };
int[] removed = ArrayUtils.removeElement(intArray, 3); 
System.out.println(Arrays.toString(removed));
 
//将int转换成字节数组
byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
 
for (byte t : bytes) {
   System.out.format("0x%x ", t);
}