Java 遍历二维数组
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Iterate through 2 dimensional array
提问by Peter111
I have a "connect four board" which I simulate with a 2d array (array[x][y] x=x coordinate, y = y coordinate). I have to use "System.out.println", so I have to iterate through the rows.
我有一个“连接四块板”，我用二维数组（数组 [x][y] x=x 坐标，y = y 坐标）模拟它。我必须使用“System.out.println”，所以我必须遍历行。
I need a way to iterate this way [0,0] [1,0] [2,0] [3,0] [0,1] [1,1] [2,1] etc
我需要一种以这种方式迭代的方法 [0,0] [1,0] [2,0] [3,0] [0,1] [1,1] [2,1] 等
If i use the normal procedure:
如果我使用正常程序：
for (int i = 0; i<array.length; i++){
for (int j = 0; j<array[i].length; j++){
string += array[i][j];
} System.out.println(string)
}
it doesnt work because it iterates this way [0,0] [0,1] [0,2] [0,3] etc
它不起作用，因为它以这种方式迭代 [0,0] [0,1] [0,2] [0,3] 等
The normal procedure stays in x and increments y until the end of the column, but i need to say in y and increment x until the end of the row.
正常过程停留在 x 并增加 y 直到列的末尾，但我需要在 y 中说并增加 x 直到行的末尾。
回答by Mateusz Dymczyk
Simple idea: get the lenght of the longest row, iterate over each column printing the content of a row if it has elements. The below code might have some off-by-one errors as it was coded in a simple text editor.
简单的想法：获取最长行的长度，迭代每一列，如果它有元素，则打印一行的内容。下面的代码可能有一些逐一错误，因为它是在一个简单的文本编辑器中编码的。
int longestRow = 0;
for (int i = 0; i < array.length; i++) {
if (array[i].length > longestRow) {
longestRow = array[i].length;
}
}
for (int j = 0; j < longestRow; j++) {
for (int i = 0; i < array.length; i++) {
if(array[i].length > j) {
System.out.println(array[i][j]);
}
}
}
回答by jcstar
Just invert the indexes' order like this:
只需像这样反转索引的顺序：
for (int j = 0; j<array[0].length; j++){
for (int i = 0; i<array.length; i++){
because all rows has same amount of columns you can use this condition j < array[0].lengt in first for condition due to the fact you are iterating over a matrix
因为所有行都具有相同数量的列，您可以首先使用此条件 j < array[0].lengt 作为条件，因为您正在迭代矩阵
回答by Bharat
Consider it as an array of arrays and this will work for sure.
将其视为一个数组数组，这肯定会起作用。
int mat[][] = { {10, 20, 30, 40, 50, 60, 70, 80, 90},
{15, 25, 35, 45},
{27, 29, 37, 48},
{32, 33, 39, 50, 51, 89},
};
for(int i=0; i<mat.length; i++) {
for(int j=0; j<mat[i].length; j++) {
System.out.println("Values at arr["+i+"]["+j+"] is "+mat[i][j]);
}
}
回答by BadNews
Just change the indexes. i and j....in the loop, plus if you're dealing with Strings you have to use concat and initialize the variable to an empty Strong otherwise you'll get an exception.
只需更改索引。i 和 j.... 在循环中，此外，如果您正在处理字符串，则必须使用 concat 并将变量初始化为空的 Strong，否则您将收到异常。
String string="";
for (int i = 0; i<array.length; i++){
for (int j = 0; j<array[i].length; j++){
string = string.concat(array[j][i]);
}
}
System.out.println(string)
回答by Niamatullah Bakhshi
//This is The easiest I can Imagine .
// You need to just change the order of Columns and rows , Yours is printing columns X rows and the solution is printing them rows X columns
for(int rows=0;rows<array.length;rows++){
for(int columns=0;columns <array[rows].length;columns++){
System.out.print(array[rows][columns] + "\t" );}
System.out.println();}
