Arrays实用功能

1.打印数组内容
Arrays.toString(arr)

   public static void main(String[] args) {
        int[] arr1 = new int[3];
        int[] arr2 = new int[5];
        Arrays.fill(arr1,11);
        Arrays.fill(arr2,22);
        System.out.println("arr1 = [" + Arrays.toString(arr1) + "]");
        System.out.println("arr2 = [" + Arrays.toString(arr2) + "]");
    }
  
    输出结果：
    arr1 = [[11, 11, 11]]
    arr2 = [[22, 22, 22, 22, 22]]

2. 比较两个数组是否相等,Arrays.equals(arr1,arr2);

	   public static void main(String[] args) {
		        int[] arr1 = new int[3];
		        int[] arr2 = new int[5];
		        int[] arr3 = new int[5];
		        Arrays.fill(arr1,11);
		        Arrays.fill(arr2,22);
		        Arrays.fill(arr3,22);
		        System.out.println("arr1==arr2 ["+ Arrays.equals(arr1,arr2)+"]");
		        System.out.println("arr2==arr3 ["+ Arrays.equals(arr2,arr3)+"]");
	    }
	    
	   输出结果：
	   arr1==arr2 [false]
	   arr2==arr3 [true]

3. 数组排序，Arrays.sort();

   	   public static void main(String[] args) {
	        int[] arr1 = {1,3,2};
	        String[] arr2 = {"a","bc","aa","ss"};
	        Arrays.sort(arr1);
	        Arrays.sort(arr2);
	        System.out.println("arr1 = [" + Arrays.toString(arr1) + "]");
	        System.out.println("arr2 = [" + Arrays.toString(arr2) + "]");
	    }
	    
	    输出结果：
	    arr1 = [[1, 2, 3]]
	    arr2 = [[a, aa, bc, ss]]

4. 复制数组
   使用System.arraycopy(arr1,0,arr2,0,arr.length)方法，表示从arr1的第0个位置开始复制到目标数组arr2的第0个位置开始，复制arr1.length个元素。注意异常。是一种浅复制，如果数组元素为对象只复制了对象的引用而不是对象本身。比for循环效率高。

	    public static void main(String[] args) {
	        String[] arr1 = {"1","3","2"};
	        String[] arr2 = {"a","bc","aa","ss"};
	        Arrays.sort(arr1);
	        Arrays.sort(arr2);
	        System.arraycopy(arr1,0,arr2,1,2);
	        System.out.println("arr1 = [" + Arrays.toString(arr1) + "]");
	        System.out.println("arr2 = [" + Arrays.toString(arr2) + "]");
	    }
	    
	    输出结果：
	    arr1 = [[1, 2, 3]]
	    arr2 = [[a, 1, 2, ss]]
   

5. Arrays.asList()接受一个数组或者一个用逗号分隔的元素列表将其转化为list

	   public static void main(String[] args) {
	        String[] arr1 = {"1","3","2"};
	        String str = "a,b,c,d";
	        List list = Arrays.asList(arr1);
	        List listStr = Arrays.asList(str);
	        System.out.println("list = [" + list. + "]");
	        System.out.println("listStr = [" + listStr + "]");
	    }