Question

如何在循环时将两个元素添加到2D数组中。

for(...){
gradeArray[i][i] (gradeArray[95][5]  <---- i = 0, gets the zero term for the grade and frequency 
gradeArray[i][i] (gradeArray[96][2] <-----i = 1; gets the first term for the grade and frequency

Answer 1

在我看来，你想知道每个年级发生的次数。我认为你最好的选择是HashMap：

Map<Integer, Integer> frequencyTable = new HashMap<Integer, Integer>();
for (Integer grade : gradeArray) {
    if (!frequencyTable.containsKey(grade)) {
        frequencyTable.put(grade, Collections.frequency(gradeArray, grade));
    }
}

Answer 2

您的新编辑仍然让我感到困惑，但这就是我能想到的所有问题：

int[][] gradesAndFrequencies = new int[gradeCount][2];
for (int i = minGrade; i < maxGrade; i++) {
    int grade = ?;
    int frequency = ?;
    gradesAndFrequencies[i][0] = grade;
    gradesAndFrequencies[i][1] = frequency;
}

这假设您知道总共有多少等级，您知道如何找到每个等级及其频率。

我仍然支持我之前对Ted Hopp回答的评论：如果没有任何关于你想要做什么的额外信息，我不得不说这不是你数据的好模型。

Answer 3

你不会喜欢它，但这是怎么回事。因此，数组是不可变的。所以，为了避免这个问题，我会使用一个可变的ArrayList。但要回答你的问题（假设尺寸为95x95）：

int newGradeArray[][] = new int[96][96]; //creating a new array that has an extra column and row, for more space.
for(int i = 0; i < 95; i++)//a set of nested loops taking everything from the old array, and moving it to this new one.
    for(int j = 0; j < 95; j++)
        newGradeArray[i][j] = gradeArray[i][j]
//now to add the elements (in the new element or column, your choice)
newGradeArray[95][95] = 95; //assigns the very edge of the new array a value of 95

或者，您可以使用ArrayList。这样，您不需要创建新数组并重新分配，您可以执行以下操作：

ArrayList<Integer> a = new ArrayList<Integer>(); //note: ArrayLists can only have classes, not primitive types. Luckily, Integer and I think Character are classes too!
a.add(95, new Integer(95)); //sets the index of 95 as an Integer: 95.

这些可以是二维的。或者：

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

甚至：的ArrayList＆GT; l = new ArrayList＆gt;（）; 如果你想：）

希望这有帮助！

Answer 4

只使用2个列表，一个用于成绩，一个用于频率

使用：

List<Integer> grades = new ArrayList<Integer>();
List<Integer> freq = new ArrayList<Integer>();
grades.add(grade);
freq.add(frequency);

添加到他们

这会更简单。

示例：

while(1 == 1) //infinite loop
{
    grade = -1
    frequency = -1
    grade = inputGrade.nextInt();
    frequency = inputFrequency.nextInt();
    if(grade != -1 && frequency != -1)
    {
        grades.add(grade);
        freq.add(frequency);
    }
    else
    {
    //if using a command window
    System.out.println("Missing either frequency or grade, values not stored");
    //if not using a command window
    JOptionPane.showMessageDialog(null, "Missing either frequency or grade, values not stored");
    }
}

添加到2D阵列

4 个答案: