每个循环的Java数据类型不匹配

I was converting a bunch of ordinary for loops to for-each loops in my most recent project and ran into a paradoxical problem.

在我最近的一个项目中，我正在将一堆普通的for循环转换成for-each循环，并遇到了一个矛盾的问题。

    imgMap = new int[rows][cols];

    for (int r=0; r<imgMap.length; r++) {
        rowArray = mapBR.readLine().split(",");
        for (int c=0; c<imgMap[r].length; c++) {
            imgMap[r][c] = Integer.parseInt(rowArray[c]);
        }
    }

    System.out.println(imgMap.length+", "+imgMap[0].length);

    // print array in rectangular form
    for (int[] r : imgMap) {
        for (int[] c : imgMap[r]) {
            System.out.print(" " + c[0]);
        }
        System.out.println("");
    }

imgMap is a two-dimensional int array (int[][]) to hold a 'map'
mapBR is a BufferedReader of the external file that the 'map' is taken from
The first nested for loop set reads the file, the second nested for-each set writes it to the console to make sure that it is read correctly.

int imgMap是一个二维数组(int[][])举行“地图”mapBR是BufferedReader外部文件的“地图”是来自第一个嵌套循环读取文件,第二组嵌套for - each写控制台,以确保它是正确读取。

I couldn't see a way to make the first for loop set work as for-each loops so that is a sub-problem I would be delighted if someone could help me with as well.

我不知道如何使第一个for循环集作为for-each循环工作，所以如果有人也能帮助我，我将很高兴这是一个子问题。

Anyway, back to the main problem. when I (try to) compile this the compiler regurgitates an error saying that the int[] c : imgMap[r] line has incompatible types, but, and here's the catch, when I change it to int c : imgMap[r], it coughs up the same error! As I can't see how it could be any other than one of those types I am flummoxed.

不管怎样，回到主要问题。当我(尝试)编译它时，编译器会返回一个错误，说int[] c: imgMap[r]行有不兼容的类型，但是，当我将它改为int c: imgMap[r]时，它会产生同样的错误!因为我看不出它怎么会是其他类型的，我感到困惑。

I hope I have provided enough information.

我希望我已经提供了足够的信息。

IAmThePiGuy

IAmThePiGuy

7 个解决方案

#1

In the first loop, you need c to be an int so that you can access rowArray[c] - but this should work:

在第一个循环中，您需要c为int，以便您可以访问rowArray[c]——但是这应该起作用:

for (int[] row : imgMap) {
    String[] rowArray = mapBR.readLine().split(",");
    for (int c = 0; c < row.length; c++) {
        row[c] = Integer.parseInt(rowArray[c]);            
    }
}

In the second loop, you just need to iterate through r, not through imgMap[r]:

在第二个循环中，你只需要遍历r，而不是通过imgMap[r]:

for (int[] row : imgMap) {
    for (int value : row) {
        System.out.print(" " + value);
    }
    System.out.println("");
}

Basically, you need to think carefully about the types involved - whether a variable represents an index into an array, or the array itself.

基本上，您需要仔细考虑所涉及的类型——变量是表示数组中的索引，还是数组本身。

#2

you're trying to use r, which is an int [], as just int. It is wrong. fix it to

你想用r，一个int[]，作为int，这是错的。修复它

for (int c : r) {
  ...
}

#3

int[] c : imgMap[r]

as index of array it takes int and you have supplied int[]

作为数组的索引，它需要int并且你已经提供了int[]

It should be

它应该是

   for (int[] r : imgMap) {
        for (int c : r) {
            System.out.print(" " + c);
        }
        System.out.println("");
    }

#4

This is how it works:

这就是它的工作原理:

for (int[] row : imgMap) {
  for (int cell : row) {
    System.out.print(" " + cell);
  }
  System.out.println("");
}

The outer for loop provides all rows from the matrix, the inner for loops all cells from a row.

外部for循环提供来自矩阵的所有行，内部for循环来自一行的所有单元格。

#5

for (int[] r : imgMap) {
    for (int c : r) {
        System.out.print(" " + c);
    }
    System.out.println("");
}

#6

If i understand this correct it has to be like this:

如果我理解正确的话，就应该是这样:

for (int[] r : imgMap) {
        for (int c : r) {
            ...
        }
        ...
    }

#7

You'd need to code

你需要的代码

for (int c : r)

#1