我的數組元素在Java中具有相同的ID？

Question

這基本上是一個將兩個稀疏矩陣相乘的程序。 當我想設置為對象創建的數組的元素時，我有一個SpEntry類型的數組（一個具有3個即時變量，int行，列，值和getter和setter方法的類）（m_1和m_2是SpArray類的實例） ＆每個對象都是一個SpEntry [] spArray，其大小為非零元素，當我想設置每個數組的元素時，我喜歡m_1 [0]和＆m_1 [1]（m_1數組的元素）具有相同的ID，因此當我設置m_1 [0]的行，行，列時，元素也被復制為m_1 [1]的行，行，列值。

public class SpArray {
    public static int N ; //size of NxN matrix
    private SpEntry[] spArray;

    public SpArray(int nNZ){
        spArray = new SpEntry[nNZ];  //nNZ is the number of Non-Zero elements of the sparse matrix

        SpEntry init = new SpEntry(0,0,0);
        for (int s=0; s<spArray.length ; s++){
            spArray[s]= init ; 

        }

    }




    //returns the spArray
    public SpEntry[] getSpArray (){
        return this.spArray;
    }




    //returns the spArray elements
        public SpEntry getSpArray (int index){
            return this.spArray[index];
        }

這是SpArray類的一部分，並且在主程序中：

 public static void main(String[] args) {
    int nnz_1;
    int nnz_2;
    SpArray m_1;
    SpArray m_2;


    input = new Scanner (System.in);

    System.out.println("Please enter the size of your square sparse matrix: ");
    SpArray.N = input.nextInt();

    //getting the non zero elements of the 1st sparse matrix & making its sparse array

System.out.println（“請在第一個稀疏矩陣中輸入非零元素的數量：”）; nnz_1 = input.nextInt（）;

    m_1 = new SpArray (nnz_1);

    for(int j_1=0; j_1<nnz_1 ; j_1++){
    System.out.println("Enter number "+ (j_1+1) + " non-zero element of the 1st sparse matrix");
        System.out.println("row: ");
        int r_1 = input.nextInt();
        System.out.println("column: ");
        int c_1 = input.nextInt();
        System.out.println("Value: ");
        int v_1 = input.nextInt();


        /*
        SpEntry e_1 = new SpEntry (r_1, c_1, v_1);
        m_1.getSpArray()[j_1].setRow(e_1.getRow());
        m_1.getSpArray()[j_1].setCol(e_1.getCol());
        m_1.getSpArray()[j_1].setVal(e_1.getVal());
        */

        //new versiin revised
        SpEntry e_1 = new SpEntry (r_1, c_1, v_1);
        m_1.getSpArray(j_1).setRow(e_1.getRow());
        m_1.getSpArray(j_1).setCol(e_1.getCol());
        m_1.getSpArray(j_1).setVal(e_1.getVal());**

    } 

當我調試程序時，它表明m_1的數組的元素具有相同的id（和m_2的層相同）：

m_1           Value: SpArray (id=21)`enter code here`
  spArray            SpEntry[2] (id=22)
    [0]              SpEntry   (id=661)
    [1]              SpEntry   (id=661)

Answer 1

您的問題在這里：

public SpArray(int nNZ){
    spArray = new SpEntry[nNZ];  //nNZ is the number of Non-Zero elements of the sparse matrix

    SpEntry init = new SpEntry(0,0,0);       // Problem here
    for (int s=0; s<spArray.length ; s++){
        spArray[s]= init ; 

    }

}

您只創建一個對象，然后用同一對象填充整個矩陣。

如果要使對象與眾不同，則需要為每個元素創建一個新對象：

public SpArray(int nNZ){
    spArray = new SpEntry[nNZ];  //nNZ is the number of Non-Zero elements of the sparse matrix

    for (int s=0; s<spArray.length ; s++){
        spArray[s]= new SpEntry(0,0,0) ; 

    }

}