12个操作数组的最佳方法
2015-01-13 08:40 踏雪无痕轻似燕 阅读(228) 评论(0) 编辑 收藏 举报1. 声明一个数组
- String[] aArray = new String[5];
- String[] bArray = {"a","b","c", "d", "e"};
- String[] cArray = new String[]{"a","b","c","d","e"};
2. 输出一个数组
- int[] intArray = { 1, 2, 3, 4, 5 };
- String intArrayString = Arrays.toString(intArray);
- // print directly will print reference value
- System.out.println(intArray);
- // [I@7150bd4d
- System.out.println(intArrayString);
- // [1, 2, 3, 4, 5]
3. 从一个数组创建数组列表
- 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. 检查一个数组是否包含某个值
- 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. 声明一个内联数组
- method(new String[]{"a", "b", "c", "d", "e"});
7. 把提供的数组元素放入一个字符串
- // containing the provided list of elements
- // Apache common lang
- String j = StringUtils.join(new String[] { "a", "b", "c" }, ", ");
- System.out.println(j);
- // a, b, c
8. 将一个数组列表转换为数组
- 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);
9. 将一个数组转换为集(set)
- Set set = new HashSet(Arrays.asList(stringArray));
- System.out.println(set);
- //[d, e, b, c, a]
10. 逆向一个数组
- int[] intArray = { 1, 2, 3, 4, 5 };
- ArrayUtils.reverse(intArray);
- System.out.println(Arrays.toString(intArray));
- //[5, 4, 3, 2, 1]
11. 移除数组中的元素
- int[] intArray = { 1, 2, 3, 4, 5 };
- int[] removed = ArrayUtils.removeElement(intArray, 3);//create a new array
- System.out.println(Arrays.toString(removed));
12. 将整数转换为字节数组
- byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
- for (byte t : bytes) {
- System.out.format("0x%x ", t );
}