實用的Java數組技巧

1. 聲明一個數組（Declare an array） 

String[] aArray = new String[6];
String[] bArray = {"a","b","c","d"};
String[] cArray = new String[]{"a","b","c","d"};

2.Java中輸出一個數組（Print an array in Java）

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

System.out.println(intArray);
//

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

3.從數組中建立數組列表（Create an ArrayList from an array）

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.檢查數組中是否包含特定值（Check if an array contains a certain value）

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

5.鏈接兩個數組（ Concatenate two arrays）

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.聲明一個數組內鏈（Declare an array inline ）

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

7.將數組元素加入到一個獨立的字符串中（Joins the elements of the provided array into a single String）

// 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.將數組列表轉換成一個數組 （Covnert an ArrayList to an array） 

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.將數組轉換成一個集合（Convert an array to a set） 

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

10.反向數組（Reverse an array）

int[] intArray = { 1, 2, 3, 4, 5 }; ArrayUtils.reverse(intArray); System.out.println(Arrays.toString(intArray)); //[5, 4, 3, 2, 1]

11.刪除數組元素（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));