如何通过将列表中的数组相加来获得这个2*2矩阵

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英文:

How do i get this 2*2 matrix by adding array in List

问题

  1. public class Main {
  2. public static void main(String[] args) {
  3. System.out.println("Hello World");
  4. List<List<Integer>> list = new List<List<Integer>>();
  5. list.add({1, 2, 3});
  6. list.add({3, 4, 5});
  7. list.add({6, 7, 8});
  8. System.out.println(list);
  9. }
  10. }
  1. import java.util.ArrayList;
  2. import java.util.Collections;
  3. import java.util.List;
  4. import java.util.Arrays;
  5. public class Main {
  6. public static void main(String[] args) {
  7. System.out.println("Hello World");
  8. List<List<Integer>> list = new ArrayList<>();
  9. list.add(Arrays.asList(1, 2, 3));
  10. list.add(Arrays.asList(4, 5, 6));
  11. list.add(Arrays.asList(7, 8, 9));
  12. System.out.println(list);
  13. System.out.println(list.get(0).get(0));
  14. }
  15. }
英文:
  1. public class Main
  2. {
  3. public static void main(String[] args) {
  4. System.out.println(&quot;Hello World&quot;);
  5. List&lt;List&lt;Integer&gt;&gt; list = new List&lt;List&lt;Integer&gt;&gt;();
  6. list.add({1,2,3});
  7. list.add({3,4,5});
  8. list.add({6,7,8});
  9. System.out.println(list);
  10. }
  11. }

** I want the below matrix. And i want it by adding array to the List, but i amnot getting the desire output. Please let me know what i am missing.

  1. 1 2 3
  2. 4 5 6
  3. 7 8 9

below code is working, and i have updated incase anyone needs....


  1. import java.util.ArrayList;
  2. import java.util.Collections;
  3. import java.util.List;
  4. import java.util.Arrays;
  5. public class Main
  6. {
  7. public static void main(String[] args) {
  8. System.out.println(&quot;Hello World&quot;);
  9. List&lt;List&lt;Integer&gt;&gt; list = new ArrayList&lt;&gt;();
  10. list.add(Arrays.asList(1,2,3));
  11. list.add(Arrays.asList(4,5,6));
  12. list.add(Arrays.asList(7,8,9));
  13. System.out.println(list);
  14. System.out.println(list.get(0).get(0));
  15. }
  16. }

答案1

得分: 2

你不能实例化List,因为它是一个接口,你应该使用其中一个列表实现来创建新的列表,例如ArrayList。

  1. List<List<Integer>> list = new ArrayList<>();

并将元素添加到列表中。

  1. list.add(Arrays.asList(6, 7, 8));
英文:

You cannot instantiate List because its interface you should create new list using one of list implementation e.g. Arraylist

  1. List&lt;List&lt;Integer&gt;&gt; list = new ArrayList&gt;();

and adding to list

  1. list.add(Arrays.asList(6,7,8));
  2. </details>
  3. # 答案2
  4. **得分**: 1
  5. list.forEach(rowList -&gt; {
  6. rowList.forEach(number -&gt; System.out.print(number + &quot; &quot;));
  7. System.out.println();
  8. });
  9. <details>
  10. <summary>英文:</summary>
  11. list.forEach(rowList -&gt; {
  12. rowList.forEach(number -&gt; System.out.print(number + &quot; &quot;));
  13. System.out.println();
  14. });
  15. </details>

huangapple
  • 本文由 发表于 2020年8月5日 20:30:49
  • 转载请务必保留本文链接:https://go.coder-hub.com/63265263.html
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