Java中的继承问题

我在继承遗产方面遇到了一些问题。在父类中，数组系数是私有的。我有一些访问方法，但仍然无法让它工作

import java.util.ArrayList;
public class Poly {

private float[] coefficients;
public static void main (String[] args){
    float[] fa = {3, 2, 4};
    Poly test = new Poly(fa);

}

public Poly() {
    coefficients = new float[1];
    coefficients[0] = 0;
}

public Poly(int degree) {
    coefficients = new float[degree+1];
    for (int i = 0; i <= degree; i++)
        coefficients[i] = 0;
}


public Poly(float[] a) {
    coefficients = new float[a.length];
    for (int i = 0; i < a.length; i++)
        coefficients[i] = a[i];
}

public int getDegree() {
    return coefficients.length-1;
}

public float getCoefficient(int i) {
    return coefficients[i];
}

public void setCoefficient(int i, float value) {
    coefficients[i] = value;
}

public Poly add(Poly p) {
    int n = getDegree();
    int m = p.getDegree();
    Poly result = new Poly(Poly.max(n, m));
    int i;

        for (i = 0; i <= Poly.min(n, m); i++) 
            result.setCoefficient(i, coefficients[i] + p.getCoefficient(i));
        if (i <= n) {
            //we have to copy the remaining coefficients from this object
            for ( ; i <= n; i++) 
                result.setCoefficient(i, coefficients[i]);
        } else {
            // we have to copy the remaining coefficients from p
            for ( ; i <= m; i++) 
                result.setCoefficient(i, p.getCoefficient(i));
        }
    return result;
}

public void displayPoly () {
    for (int i=0; i < coefficients.length; i++)
        System.out.print(" "+coefficients[i]);
    System.out.println();
}

private static int max (int n, int m) {
    if (n > m)
        return n;
    return m;
}

private static int min (int n, int m) {
    if (n > m)
        return m;
    return n;
}

public Poly multiplyCon (double c){
    int n = getDegree();
    Poly results = new Poly(n);
    for (int i =0; i <= n; i++){ // can work when multiplying only 1 coefficient
        results.setCoefficient(i, (float)(coefficients[i] * c)); // errors   ArrayIndexOutOfBounds for setCoefficient
       }

    return results;
   }

  public Poly multiplyPoly (Poly p){
    int n = getDegree();
    int m = p.getDegree();
    Poly result = null;
    for (int i = 0; i <= n; i++){
        Poly tmpResult = p.multiByConstantWithDegree(coefficients[i], i); //Calls new method
        if (result == null){
            result = tmpResult;
        } else {
            result = result.add(tmpResult);
        }
    }
    return result;
}
  public void leadingZero() {
    int degree = getDegree();
    if ( degree == 0 ) return;
    if ( coefficients[degree] != 0 ) return;
    // find the last highest degree with non-zero cofficient 
    int highestDegree = degree;
    for ( int i = degree; i <= 0; i--) {
         if ( coefficients[i] == 0 ) {
              highestDegree = i -1;
         } else {
              // if the value is non-zero
              break;
         }
    }
    float[] newCoefficients = new float[highestDegree + 1];
    for ( int i=0; i<= highestDegree; i++ ) {
           newCoefficients[i] = coefficients[i];
    }
    coefficients =   newCoefficients;
}

  public Poly differentiate(){
    int n = getDegree();
    Poly newResult = new Poly(n);
    if (n>0){   //checking if it has a degree
        for (int i = 1; i<= n; i++){
             newResult.coefficients[i-1]= coefficients[i] * (i); // shift degree by 1 and multiplies
     }
     return newResult;

     } else {
    return new Poly(); //empty
     }
   }


    public Poly multiByConstantWithDegree(double c, int degree){ //used specifically for multiply poly
    int oldPolyDegree = this.getDegree();
    int newPolyDegree = oldPolyDegree + degree;
    Poly newResult = new Poly(newPolyDegree);
    //set all coeff to zero
    for (int i = 0; i<= newPolyDegree; i++){
        newResult.coefficients[i] = 0;
    }
    //shift by n degree
    for (int j = 0; j <= oldPolyDegree; j++){
        newResult.coefficients[j+degree] = coefficients[j] * (float)c;
    }

    return newResult;
}
}

import java.util.ArrayList；
公共级保利{
私有浮动系数；
公共静态void main（字符串[]args）{
float[]fa={3,2,4}；
多边形测试=新多边形（fa）；
}
公共保利（）{
系数=新浮点数[1]；
系数[0]=0；
}
公共保利（国际学位）{
系数=新浮点数[度数+1]；
对于（int i=0；i我将使系数
受保护
或使用访问器方法

我不会抛出一个简单的checked
异常
。一个IllegalArgumentException将是一个更好的选择

什么是
quadCourtificates
？它们似乎不在任何地方设置。
您将系数
放置在private
中。我不会更改此设置，但我会在
Poly
类中添加一个getter方法：

public class Poly {
    //somecode here
    public float[] getCoefficients(){
        return this.coefficients;
    }
}

然后我会在其他代码中通过getter方法使用它

public QuadPoly(Poly p){
    super(p.getCoefficients);
    //some more code here
}

即使您将“系数”
设置为“受保护”
，您也在尝试访问另一个对象的“系数”字段，该字段是一个参数。因此，它与继承和问题无关。
上述代码的错误是什么？好吧，现在，当我尝试“超级（p.系数）”时，父类中的数组系数是私有的。你能给我一些提示，让第二个类中的加法和乘法方法发挥作用吗？我有点不安，在同一个24小时内看到同一个作业中的4篇文章都在同一个作业上。看，.oops。这不应该在那里。我要去cr只为这个类创建第二个数组，但这样做会破坏继承的目的。有没有一种访问器方法可以让我访问整个数组？我遇到的问题是我不确定如何让add and multiply方法工作。我应该尽可能多地使用父类的方法。我明白了，你应该如果你这样做，他们可以简单地改变。我会强烈考虑发送一个防御性拷贝或一个不可修改的集合。给他们一个私有可变变量的原始访问是一个非常糟糕的决定。
public QuadPoly(Poly p){
    super(p.getCoefficients);
    //some more code here
}