java数组

转自：http://www.iteye.com/news/28296

1. 声明一个数组

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

2. 输出一个数组

1 int[] intArray = { 1, 2, 3, 4, 5 };
2 String intArrayString = Arrays.toString(intArray);
3  
4 // print directly will print reference value
5 System.out.println(intArray);
6 // [I@7150bd4d
7  
8 System.out.println(intArrayString);
9 // [1, 2, 3, 4, 5]

3. 从一个数组创建数组列表

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

4. 检查一个数组是否包含某个值

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

5. 连接两个数组

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

6. 声明一个内联数组（Array inline）

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

7. 把提供的数组元素放入一个字符串

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

8. 将一个数组列表转换为数组

1 String[] stringArray = { "a", "b", "c", "d", "e" };
2 ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(stringArray));
3 String[] stringArr = new String[arrayList.size()];
4 arrayList.toArray(stringArr);
5 for (String s : stringArr)
6     System.out.println(s);

9. 将一个数组转换为集（set）

1 Set<String> set = new HashSet<String>(Arrays.asList(stringArray));
2 
3 System.out.println(set);
4 
5 //[d, e, b, c, a]

10. 逆向一个数组

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

11. 移除数组中的元素

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

12. 将整数转换为字节数组

1 byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
2  
3 for (byte t : bytes) {
4    System.out.format("0x%x ", t);
5 }