JAVA开发之 30-java的数组的12个最佳方法

不念不忘少年蓝@ 2022-06-15 10:10 145阅读 0赞

**1. 声明一个数组**

Java代码

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**

Java代码

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**

Java代码

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. 检查一个数组是否包含某个值**

Java代码

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**

Java代码

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）**

Java代码

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

**7. 把提供的数组元素放入一个字符串**

Java代码

// 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**

Java代码

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. 将一个数组转换为集（set）**

Java代码

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

**10. 逆向一个数组**

Java代码

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**

Java代码

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**

Java代码

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