【翻译】Java Array的排名前十方法(Top 10 Methods for Java Arrays)

这里列举了Java Array 的前十的方法。他们在stackoverflow最大投票的问题。

The following are top 10 methods for Java Array. They are the most voted questions from stackoverflow.

 

0.声明一个数组

0. Declare an array

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

 1.打印数组

1. Print an array in Java

int[] intArray = {1, 2, 3, 4, 5};
String intArrayString = Arrays.toString(intArray);

//直接输出Array，输出,内存地址:[I@4554617c
System.out.println(intArray);

//输出：[1, 2, 3, 4, 5]
System.out.println(intArrayString);

2.从数组中转为ArrayList

2. Create an ArrayList from an array

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

3.判断数组是否含有某值

3. Check if an array contains a certain value

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

4.连接两个数组

4. Concatenate two arrays

 //需要导入 org.apache.commons.lang3
 int[] intArray1 = {1, 2, 3, 4, 5};
 int[] intArray2 = {6, 7 , 8, 9, 10};
 int[] combinedIntArray = org.apache.commons.lang3.ArrayUtils.addAll(intArray1, intArray2);
 String arrayString = Arrays.toString(combinedIntArray);
 //[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
 System.out.println(arrayString);

 5.Declare an array inline  --- 不知道这个的作用

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

6.将数组的每个元素取出拼接成字符串

6. Joins the elements of the provided array into a single String

 String j = org.apache.commons.lang3.StringUtils.join(new String[] { "a", "b", "c" }, ":");
 //a:b:c
 System.out.println(j);

7.将ArrayList转换为数组

7.Covnert an ArrayList to an array

 String[] stringsArray = {"a", "b", "c", "d", "e"};
 ArrayList arrayList = new ArrayList<>(Arrays.asList(stringsArray));
 String[] stringArr = new String[arrayList.size()];
 arrayList.toArray(stringArr);

8.将数组转换为set

8. Convert an array to a set

  String[] stringsArray = {"a", "b", "c", "d", "e"};
  Set set = new HashSet(Arrays.asList(stringsArray));
  System.out.println(set);

9.反转一个数组

9. Reverse an array

 String[] stringsArray = {"a", "b", "c", "d", "e"};
 ArrayUtils.reverse(stringsArray);
 //[e, d, c, b, a]
 System.out.println(Arrays.toString(stringsArray));

10.移除数组的某个元素

10. Remove element of an array

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

One more - convert int to byte array

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