Arrays工具类十大常用方法

以下是由 stackoverflow 网站 投票决出的Java数组最常用的十个方法, 

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);
    
   

   

    

   
   

    

     }
    
   
 

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