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

Posted 2020-10-30 caorm

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:[[email protected]
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<String> 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<String> 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<String> set = new HashSet<String>(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);
}