如何添加阵列ArrayList的？ [英] How to add arrays to ArrayList?

问题描述

我有一个int [3] [3]数组，它仅包含0或1的值，
如果值是1我要添加此值的坐标ArrayList中为int [2]数组，但我不知道为什么它总是添加最后1价值坐标，是什么问题？

 公共静态无效的主要（字串[] args）{    随机随机=新的随机（）;
    INT [] =坐标INT新[2];
    ArrayList的＆LT; INT [] GT; ArrayList的=新的ArrayList＆LT;＆GT;（）;
    INT [] []板=新INT [3] [3];    的for（int i = 0; I＆LT; board.length;我++）{
        对于（INT J = 0; J＆LT;主板[I]。长度; J ++）{
            板[I] [J] = random.nextInt（2）;
        }
    }    的for（int i = 0; I＆LT; board.length;我++）{
        对于（INT J = 0; J＆LT;主板[I]。长度; J ++）{
            System.out.print（板[I] [J] +）;
            如果（板[I] [J] == 1）{
                坐标[0] = I;
                坐标[1] = j的;
                arrayList.add（坐标）;            }
        }
        的System.out.println（）;
    }    的System.out.println（包含值1细胞的坐标）;    对于（INT [] coordianate：ArrayList的）{
        的for（int i = 0; I＆LT; coordianate.length;我++）{
            System.out.print（co​​ordianate [I] +）;
        }
        的System.out.println（）;
    }
}
 

}

输出：

  1 0 1
1 1 0
1 1 0
包含1值单元格的坐标
2 1
2 1
2 1
2 1
2 1
2 1
 

解决方案

您需要创建新的坐标阵列每个 I 要在列表的地方，Ĵ对。现在要放置的同一阵列的多次，它可以记住最后一组对。

在你需要换句话说

 如果（板[I] [J] == 1）{
    坐标= INT新[2]; //添加此行
    坐标[0] = I;
    坐标[1] = j的;
    arrayList.add（坐标）;}
 

I have an int[3][3] array and it contains only 0 or 1 values, if the value is 1 I want to add the coordinates of this value in the ArrayList as int[2] array, but I don't know why it always add the last 1-value coordinates, what's the problem?

public static void main(String[] args) {

    Random random = new Random();
    int[] coordinates = new int[2];
    ArrayList<int[]> arrayList = new ArrayList<>();
    int[][] board = new int[3][3];

    for (int i = 0; i < board.length; i++) {
        for (int j = 0; j < board[i].length; j++) {
            board[i][j] = random.nextInt(2);
        }
    }

    for (int i = 0; i < board.length; i++) {
        for (int j = 0; j < board[i].length; j++) {
            System.out.print(board[i][j] + " ");
            if (board[i][j] == 1){
                coordinates[0] = i;
                coordinates[1] = j;
                arrayList.add(coordinates);

            }
        }
        System.out.println();
    }

    System.out.println("coordinates of cells that contain 1 value");

    for (int[] coordianate : arrayList) {
        for (int i = 0; i < coordianate.length; i++) {
            System.out.print(coordianate[i] + " ");
        }
        System.out.println();
    }
}

}

output:

1 0 1 
1 1 0 
1 1 0 
coordinates of cells that contain 1 value
2 1 
2 1 
2 1 
2 1 
2 1 
2 1 

解决方案

You need to create new coordinates array for each i,j pair you want to place in your list. For now you are placing same array multiple times which remembers last set pair.

In other words you need to

if (board[i][j] == 1) {
    coordinates = new int[2];//add this line
    coordinates[0] = i;
    coordinates[1] = j;
    arrayList.add(coordinates);

}

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