如何从方法返回数组？

Question

我是编程初学者，希望有人能帮助我解决我的问题，请

public int [][]matrixSetup(String size, char i) throws IOException { 

    int size_num = Integer.parseInt(size); 

    if (size_num > 1 && size_num < 4) { 
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 


    System.out.println("input the value store them, they arrange as" + i + "11,"+ i+ "12," + i +"21,"+ i +"22 etc"); 

    for(int row = 0; row < size_num ; row++) 
     for(int col = 0 ; col < size_num ; col++){ 
      int [][]A = new int [size_num][size_num]; 
      String ipS = br.readLine();      //ipS = input String 
      int input_value = Integer.parseInt(ipS); 
      A[row][col] = input_value;   
     } 
    } else System.out.println("invalid matrix size!"); 
    return A; //How to return the matrix? 
} 

Answer 1

要回答你的问题“如何来回报矩阵”：你已经在做了正确的方式。从目前为止的评论中可以看出，问题在于A的声明。

A声明和内部初始化for -loop：

int [][]A = new int [size_num][size_num]; 

因此其知名度仅限于for -loop。为了使A可见你必须移动它的声明中已经存在的return声明：

int size_num = Integer.parseInt(size); 
int[][] A = new int[size_num][size_num]; 
if (size_num > 1 && size_num < 4) { 
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
    for(int row = 0; row < size_num ; row++) 
    for(int col = 0 ; col < size_num ; col++){ 
     String ipS = br.readLine(); 
     int input_value = Integer.parseInt(ipS); 
     A[row][col] = input_value; 
    } 
} else { 
    System.out.println("invalid matrix size!"); 
} 
return A;