一、Array与List相互转换

List----->Arrray

List
    
      users =new ArrayList<>();        users.add(new User(11,"aa",112));        users.add(new User(22,"bb",222));        users.add(new User(22,"bb",332));        users.add(new User(33,"cc",332));        users.add(new User(33,"cc",332));        users.add(new User(33,"cc",3311));        User[] strings = new User[users.size()];        users.toArray(strings);        System.out.println(strings.toString());
    

 

Array---->List

String[] s = {"a","b","c"};        List
    
      list2 = java.util.Arrays.asList(s);        System.out.println(list2.toString());
    

 

二、12个最佳方法

http://www.iteye.com/news/28296

import org.apache.commons.lang.ArrayUtils;

引入pom.xml

       
     
      org.apache.commons
        
     
      commons-lang3
        
     
      3.5
     
    

1.  声明一个数组 

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

2.  输出一个数组 

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.  从一个数组创建数组列表   Array--->List

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

4.  检查一个数组是否包含某个值 

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

5.  连接两个数组 

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.  声明一个内联数组（Array inline） 

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

7.  把提供的数组元素放入一个字符串 

// 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.  将一个数组列表转换为数组   List--->Array

String[] stringArray = { "a", "b", "c", "d", "e" };  ArrayList
    
      arrayList = new ArrayList
     
      (Arrays.asList(stringArray));  String[] stringArr = new String[arrayList.size()];  arrayList.toArray(stringArr);  for (String s : stringArr)      System.out.println(s);
     
    

9.  将一个数组转换为集（set） 

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

10.  逆向一个数组 

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

11.  移除数组中的元素 

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

12.  将整数转换为字节数组 

byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();        for (byte t : bytes) {            System.out.format("0x%x ", t);        }        //0x0 0x0 0x0 0x8