Array reverse output

I just started to learn java, please help look randomly generated integers less than 10 100 , respectively, according to their positive sequence and reverse sequence output
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int []arr=new int[10];
  		System.out.println("随机数的顺序是：");
  		for(int a = 0 ;a<10;a++){
  			int random = (int) (Math.random()*100);
  			arr[a]=random;
  			System.out.print(" "+random);
  		}
  		System.out.println();
  		System.out.println("正序是");
  		for(int b :arr){
  			System.out.print(" "+b);
  		}
  		System.out.println();
  		System.out.println("逆序是：");
  		for(int c = 9;c>=0;c--){
  			System.out.print(" "+arr[c]);
  		}

------ Solution - ------------------------------------------

public class Test {
  
  	public static void main(String[] args) {
  		int a[] = new int[10];
  		
  		for(int i=0;i<a.length;i++){
  			a[i] = (int)(Math.random()*100);
  		}
  		
  		Arrays.sort(a);
  		//升序
  		System.out.println("升序");
  		for(int i=0;i<a.length;i++){
  			System.out.print(a[i] + " ");
  		}
  		System.out.println();
  		
  		//降序
  		System.out.println("降序");
  		for(int i=a.length-1;i>=0;i--){
  			System.out.print(a[i] + " ");
  		}
  		System.out.println();
  	}
  }
  

Arrays.sort (a); own sorting algorithm in Java , you can also write your own sorting algorithm to sort
Math.random (); is a randomly generated number between 0.0 and 1.0 * 100 is a number between 0 and 100 a
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for (int i = 0; i<arr.length;i++){
  			 arr[i] = (int)(Math.random() * 100);
  		 }
  		 
  		 System.out.println(Arrays.toString(arr));

reverse method and two upstairs same, do not write
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upstairs can !
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ArrayList<Integer> list = new ArrayList<>(100);
  ThreadLocalRandom generator = ThreadLocalRandom.current();
  for(int i = 0; i < 10; ++i){
      list.add(generator.nextInt(0,100)); //  [0, 100)
  }
  Collections.sort(list);
  System.out.println(list);
  Collections.reverse(list);
  System.out.println(list):

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let you say
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Mmm
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Thank you , too thanked