Java從一個主函數調用打印方法並使用來自另一個單獨方法的數據

Question

我試圖運行一個程序，該程序從用戶輸入構造一個2D數組，然後打印該數組。該數組必須在一個方法中構造並以單獨的方法打印行。我只打算在新行上打印數組中的每一行。我不知道如何將數組從一種方法拉到另一種方法。

代碼被設置成當main方法被調用它會調用「構造」的方法來構建數組，然後數組建成後它就會採取陣列和數據發送到打印方法打印每一行。我不確定從代碼中的哪個位置開始，但我仍然不明白如何從不同的方法提取數據。

package workfiles; 

import java.util.*; 
import java.util.Scanner; 

public class hw2 
{ 
    // Do not modify this method 
    public static void main(String[] args) 
    { 
     try { 
      int[][] iArray = enter2DPosArray(); 
      System.out.println("The original array values:"); 
      print2DIArray(iArray); 

      int[][] tArray = transposition(iArray); 
      System.out.println("The transposed array values:"); 
      print2DIArray(tArray); 
     } catch (InputMismatchException exception) { 
      System.out.println("The array entry failed. The program will now halt."); 
     } 
    } 

    // A function that prints a 2D integer array to standard output 
    // THIS METHOD IS THE ONE THAT IS SUPOSED TO PRINT THE ROWS ON NEW LINES 
    public static void print2DIArray(int[][] output) 
    { 
     int[][] iArray; 

     for (int row = 0; row < iArray.length; row++) { 
      for (int column = 0; column < iArray[row].length; column++) { 
       System.out.print(iArray[row][column] + " "); 
      } 
      System.out.println(); 
     } 
    } 

    // A function that enters a 2D integer array from the user 
    // It raises an InputMismatchException if the user enters anything other 
    // than positive (> 0) values for the number of rows, the number of 
    // columns, or any array entry 
    public static int[][] enter2DPosArray() throws InputMismatchException 
    { 
     int row = 0, col = 0, arow = 0, acol = 0, holder; 

     Scanner numScan = new Scanner(System.in); 

     while (row <= 0) { 
      System.out.print("How many rows (>0) should the array have? "); 
      row = numScan.nextInt(); 
     } 

     while (col <= 0) { 
      System.out.print("How many columns (>0) should the array have? "); 
      col = numScan.nextInt(); 
     } 

     int[][] iArray = new int[row][col]; 

     while (arow < row) { 
      while (acol < col) { 
       System.out.println("Enter a positive (> 0) integer value: "); 
       holder = numScan.nextInt(); 
       iArray[arow][acol] = holder; 
       acol++; 
      } 

      if (acol >= col) { 
       acol = 0; 
       arow ++; 
      } 
     } 

     //arrayName[i][j] 
     numScan.close(); 
     return iArray; 
    } 

    public static int[][] transposition(int[][] iArray) 
    { 
     int r = 0, c = 0; 

     int[][] transpose = new int[r][c]; 
     for (int i = 0; i < r; i++) { 
      for (int j = 0; j < c; j++) { 
       transpose[i][j] = iArray[j][i]; 
      } 
     } 
     return transpose; 
    } 
} 

Answer 1

public static void print2DIArray(int[][] output) {  
    int[][] iArray; 
    for (int row = 0; row < iArray.length; row++) { 

當你調用print2DIArray方法，你正試圖重複剛纔創建的空數組了。我想你想遍歷你通過「輸出」參數

Answer 2

您可以只改變名稱的方法是這樣的：

print2DIArray(int[][] iArray) 

所以，你的代碼看起來應該是這樣

//your array can send like an attribute, you can use it like is it 
public static void print2DIArray(int[][] iArray) { 
    //int[][] iArray you dont need to use another array here 

    for (int row = 0; row < iArray.length; row++) { 
    //... 

Answer 3

我編輯過你的代碼。我希望這會有所幫助。

public class Test { 

    private static int[][] iArray ; 

    public static void main(String[] args) { 


    try 
    { 
     int [][] iArray = enter2DPosArray(); 
     System.out.println("The original array values:"); 
     print2DIArray(iArray); 
     int [][] tArray = transposition(iArray); 
     System.out.println("The transposed array values:"); 
     print2DIArray(tArray); 
    } 

    catch (InputMismatchException exception) 
    { 
     System.out.println("The array entry failed. The program will now halt."); 
    } 

} 

    // A function that prints a 2D integer array to standard output 
    // THIS METHOD IS THE ONE THAT IS SUPPOSED TO PRINT THE ROWS ON NEW LINES 

    public static void print2DIArray(int[][] output) { 
     //int iArray[][] = new int[0][]; 

     for (int row = 0; row < iArray.length; row++) { 
      for (int column = 0; column < iArray[row].length; column++) { 
       System.out.print(iArray[row][column] + " "); 
      } 
      System.out.println(); 
     } 
    } 



    // A function that enters a 2D integer array from the user 
// It raises an InputMismatchException if the user enters anything other 
// than positive (> 0) values for the number of rows, the number of 
// columns, or any array entry 
    public static int[][] enter2DPosArray() throws InputMismatchException { 

     int row=0; 
     int col=0; 
     int arow=0; 
     int acol=0; 
     int holder; 
     Scanner numScan = new Scanner(System.in); 

     while (row<=0){ 
      System.out.print("How many rows (>0) should the array have? "); 
      row = numScan.nextInt(); 
     } 

     while (col<=0){ 
      System.out.print("How many columns (>0) should the array have? "); 
      col = numScan.nextInt(); 
     } 
     iArray = new int[row][col]; 

     while (arow < row) { 

      while (acol < col) { 
       System.out.println("Enter a positive (> 0) integer value: "); 
       holder = numScan.nextInt(); 
       iArray[arow][acol] = holder; 
       acol++; 
      } 

      if (acol >= col) { 
       acol = 0; 
       arow ++; 

      } 

     } 
     //arrayName[i][j] 
     numScan.close(); 
     return iArray; 
    } 

    public static int[][] transposition(int [][] iArray) { 

     int r=0, c=0; 

     int[][] transpose = new int[r][c]; 
     for (int i = 0; i < r; i++) { 
      for (int j = 0; j < c; j++) { 
       transpose[i][j] = iArray[j][i]; 
      } 
     } 
     return transpose; 
    } 

}