JAVA基础——Arrays工具类十大常用方法

Arrays工具类十大常用方法

原文链接:http://blog.csdn.net/renfufei/article/details/16829457

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);  }  

 相关阅读:

1. Example of Sorting Arrays
2. Read bytes from FileInputStream in Java
3. Java: convert a file to a byte array, then convert byte array to a file.
4. Top 10 questions about Java Collections