Arrays类的十大用法

还有很多地方需要细细斟酌

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);  
}