내 코드가 잘못된 배열을 수정하는 이유는 무엇입니까?

Question

이이 내 테스트 클래스

import java.util.Arrays; 
public class MatrixTest { 
    public static void main(String[] args) { 
    /* test cases for Matrix class methods */ 
    double[][] matrixA = {{1,2,3,4},{2,4,6,8},{9,10,11,12}}; 
    double[][] matrixB = {{0.92,-900,44},{1201,18.264,-21.0},{0,0,0}}; 
    double[][] matrixC = {{1.5E-12,-6.034E2},{41.8,-125E-3}}; 
    Matrix One = new Matrix(matrixA); 
    Matrix Two = new Matrix(matrixB); 
    Matrix Three = new Matrix(matrixC); 

    /* test whether or not maxRow works properly */ 
    if (One.maxRow(0) == 2) { 
      System.out.println("Passed maxRow test for matrix One"); } 
    else { System.out.println("Failed maxRow test for matrix One"); } 
    if (Two.maxRow(1) == 1) { 
      System.out.println("Passed maxRow test for matrix Two"); } 
    else { System.out.println("Failed maxRow test for matrix Two"); } 

    /* test whether or not scaleRow works properly */ 
    One.scaleRow(0,2.0); // scale row 0 by 2.0 
    if (Arrays.equals(One.getRow(0),matrixA[1])) { 
      System.out.println("Passed scaleRow test for matrix One"); } 
    else { System.out.println("Failed scaleRow test for matrix One"); } 
    Two.scaleRow(2,12.608); // scale row 2 by 12.608 
    if (Arrays.equals(Two.getRow(2),matrixB[2])) { 
      System.out.println("Passed scaleRow test for matrix Two"); } 
    else { System.out.println("Failed scaleRow test for matrix Two"); } 
    One.scaleRow(0,0.5); // scale row 0 by 0.5 
    if (Arrays.equals(One.getRow(0),matrixA[0])) { 
      System.out.println("Passed scaleRow test for matrix Three"); } 
    else { System.out.println("Failed scaleRow test for matrix Three"); } 

    for(int i = 0; i < matrixA[2].length; i++){ 
     System.out.println(matrixA[2][i]); 
    } 
    System.out.println("This prints row 2 of matrixA before the swap"); 

    /* test whether or not swap method works properly */ 
    One.swap(2,0); // swap contents of Row 2 with Row 0 
    if (Arrays.equals(One.getRow(0),matrixA[2]) && 
     Arrays.equals(One.getRow(2),matrixA[0])) { 
      System.out.println("Passed swap test for matrix One"); } 
    else { 
     double[] row0 = One.getRow(0); 
     for(int i = 0; i < row0.length; i++){ 
      System.out.println(row0[i]); 
     } 
     System.out.println("This prints row 0 of One after the swap"); 
     for(int i = 0; i < row0.length; i++){ 
      System.out.println(matrixA[2][i]); 
     } 
     System.out.println("This prints row 2 of matrixA after the swap"); 
     System.out.println("Failed swap test for matrix One"); 
    } 
    Two.swap(0,1); Two.swap(1,2); Two.swap(1,0); // fancy swap sequence 
    if (Arrays.equals(Two.getRow(0),matrixB[2]) && 
     Arrays.equals(Two.getRow(2),matrixB[0])) { 
      System.out.println("Passed swap test for matrix Two"); } 
    else { System.out.println("Failed swap test for matrix Two"); } 

    } 
    } 

내 방법

public class Matrix { 
    //this is the stored matrix given from another class 
    private double[][] stored; 

    //constructor 
    public Matrix(double[][] input){ 
    stored = input; 
    } 

    public double[] getRow(int rownum){ 
    return stored[rownum]; 
    } 

    //change current matrix by swapping rows rowA and rowB 
    public void swap(int rowA, int rowB){ 
    double[] temp = stored[rowA]; 
    stored[rowA] = stored[rowB]; 
    stored[rowB] = temp; 
    } 

    // looking only at column column_num in matrix, 
    // return index of which row has largest value 
    public int maxRow(int column_num){ 
    double largest = 0.0; //current largest value 
    int index = 0; //index of row with largest value 
    for(int i = 0; i < stored.length; i++){ 
     if(stored[i][column_num] > largest){ 
     largest = stored[i][column_num]; 
     index = i; 
     } 
    } 
    return index; 
    } 

    //method to iterate through a row and scale by factor 
    public void scaleRow(int rownum, double factor){ 
    for(int i = 0; i < stored[rownum].length; i++){ 
     double cValue = stored[rownum][i]; 
     stored[rownum][i] = cValue*factor; 
    } 
    } 

} 

내 클래스입니다 이건 내 출력 내가 스왑에를 수행 한 후 MatrixA가 수정되는 이유는

Passed maxRow test for matrix One 
Passed maxRow test for matrix Two 
Passed scaleRow test for matrix One 
Passed scaleRow test for matrix Two 
Passed scaleRow test for matrix Three 
9.0 
10.0 
11.0 
12.0 
This prints row 2 of matrixA before the swap 
9.0 
10.0 
11.0 
12.0 
This prints row 0 of One after the swap 
1.0 
2.0 
3.0 
4.0 
This prints row 2 of matrixA after the swap 
Failed swap test for matrix One 
Failed swap test for matrix Two 

하나?

* 참고 모든 인쇄 서식을 사용하고 싶지 않기 때문에 아래쪽으로 인쇄합니다.

Answer 1

매트릭스 내 생성자 단지 복사 배열 참조 :

가

public Matrix(double[][] input){ 
    stored = input; 
} 

이 떨어 지므로 matrixA 및 One 객체에 포함 된 배열과 동일한 배열이다.

원래의 입력 배열을 수정하여 Matrix 인스턴스를 원하지 않는 경우, 당신은 배열을 복사 만들어야합니다

public Matrix(double[][] input){ 
    // stored = Arrays.copyOf(input,input.length); // this would only work for 1D arrays 
    stored = new double[input.length][]; 
    for (int i = 0; i < input.length; i++) 
     stored[i] = Arrays.copyOf(input[i],input[i].length); 
}