JAVA开发之 30-java的数组的12个最佳方法

1. 声明一个数组

Java代码

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

Java代码

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

Java代码

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

Java代码

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

Java代码

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（Array inline）

Java代码

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

7. 把提供的数组元素放入一个字符串

Java代码

// 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

Java代码

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）

Java代码

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

10. 逆向一个数组

Java代码

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

Java代码

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

Java代码

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