java 如何在二维 ArrayList 上调用 .get()
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How do I call .get() on a 2d ArrayList
提问by papercuts
I have a 2d ArrayList
我有一个 2d ArrayList
ArrayList<ArrayList<String>> list = new ArrayList<ArrayList<String>>();
I want to get the item at say (0,0).
我想在 say (0,0) 处获取该项目。
I'm looking for something like:
我正在寻找类似的东西：
list.get(0,0)
Thanks!
谢谢！
回答by Hyman
You must use
你必须使用
list.get(0).get(0)
since you are not using a real 2-dimensional Listbut a Listof Lists.
因为你没有使用真正的2维List而是List的Lists。
回答by Bhesh Gurung
As follows
如下
String value = list.get(0).get(0);
回答by Ted Hopp
Java doesn't have 2d lists (or arrays, for that matter). Use something like this:
Java 没有二维列表（或数组，就此而言）。使用这样的东西：
list.get(0).get(0)
Note that arrays have a similar issue. You do not do this:
请注意，数组也有类似的问题。你不要这样做：
array[0,0] // WRONG! This isn't Fortran!
Instead you do this:
相反，你这样做：
array[0][0]
回答by Aravinth
This is a program to traverse the 2D-ArrayList. In this program instead of LineXyour can get item in the list (i , j ) :-)
这是一个遍历 2D-ArrayList 的程序。在这个程序而不是LineX 中，您可以获得列表中的项目 (i , j ) :-)
PROGRAM:
程序：
Scanner scan = new Scanner(System.in);
int no_of_rows = scan.nextInt(); //Number of rows
int no_of_columns = scan.nextInt(); //Number of columns
ArrayList<ArrayList<String>> list = new ArrayList<>();
for (int i = 0; i < no_of_rows; i++) {
list.add(new ArrayList<>()); //For every instance of row create an Arraylist
for (int j = 0; j < no_of_columns; j++) {
list.get(i).add(scan.next()); //Specify values for each indices
}
}
//ArrayList Travesal
for (int i = 0; i < list.size(); i++) {
for (int j = 0; j < list.get(i).size(); j++) {
System.out.print(list.get(i).get(j)+" "); //LineX
}
System.out.println();
}
OUTPUT:
输出：
2 3
1 2 3 4 5 6
1 2 3
4 5 6
回答by Jeevan Patil
It being List of List, you try :
它是列表列表，您尝试：
String val = list.get(0).get(0);
