關於 Java 數組的 12 個最佳方法

 

1.  聲明一個數組

 

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

 

 

2.  輸出一個數組

 

    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.  從一個數組建立數組列表

 

    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.  檢查一個數組是否包含某個值

 

    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

 

    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.  聲明一個內聯數組（Array inline）

 

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

 

7.  把提供的數組元素放入一個字符串

 

    // 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.  將一個數組列表轉換爲數組

 

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.  將一個數組轉換爲集（set）

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

 

10.  逆向一個數組

 

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

 

11.  移除數組中的元素

 

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

 

12.  將整數轉換爲字節數組

 

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

 

 

  轉自： 【ITEYE】http://www.iteye.com/news/28296