用兩個隨機數組打印Arraylist

Question

有人告訴我什麼是錯的。我想用兩個帶有自由度數字的動態數組來生成一個Arraylist。例如，我想打印一個7行5列的矩陣。而且我也不會在我的矩陣中有重複。

ArrayList<int[]> lottoraws= new ArrayList<int[]>(); 

    int[] a = new int[5]; 
    int[] b = new int[7]; 

    for (int i = 0; i < 7; i++) { 
     int rand = (int) (Math.random() * 35 + 1); 
     b[i] = rand; 

     for (int j = 0; j < 5; j++) { 
      int rand2 = (int) (Math.random() * 35 + 1); 
      a[j] = rand2; 
    } 
    } 
    lottoraws.add(a); 
    lottoraws.add(b); 

    System.out.println("The players row: \n" + Arrays.toString(lottoraws.get(0))); 

Answer 1

這樣的事情？

int[][] a = new int[7][5]; 
    for (int i = 0; i < a.length; i++) { 
     for(int j = 0; j < a[0].length ; j++){ 
      a[i][j] = (int) (Math.random() * 35 + 1); 
     } 
    } 

Answer 2

請在下面嘗試，您可以根據需要更改隨機方案。

ArrayList<int[]> lottoraws = new ArrayList<int[]>(); 
    int[] a = {}; 

    Random random = new Random(); 
    for (int i = 0; i < 7; i++) { 

     a = new int[5]; 

     for (int j = 0; j < 5; j++) { 
      int rand2 = (int) (random.nextInt(200)); 
      a[j] = rand2; 
     } 
     lottoraws.add(a); 
    } 

    for(int k=0; k< lottoraws.size(); k++){ 
     System.out.println(Arrays.toString(lottoraws.get(k))); 
    } 
}