Java extends inheritance 程序不工作？

Question

所以我有 3 个文件 - 在其中一个文件中出现此错误：

Package in class Package cannot be applied to given types; required int, char / Found no arguments

我已经尝试了所有可能想到的方法，但无法弄清楚如何修复它，这可能是菜鸟错误！？所以我希望有人能帮助解释我做错了什么。我会在下面粘贴代码！

Package.java

package chap10q5;

/**
 *
 * @author james
 */
public class Package {
    int weight;
    char shippingMethod;
    double shippingcost;

public Package(int weight, char shippingMethod){
    this.weight = weight;
    this.shippingMethod = shippingMethod;

    if( (this.weight > 0 && this.weight <= 8) && this.shippingMethod == 'A'){
        this.shippingcost = 2.00;
    }
    else if( (this.weight > 0 && this.weight <= 8) && this.shippingMethod == 'T'){
        this.shippingcost = 1.50;
    }
    else if( (this.weight > 0 && this.weight <= 8) && this.shippingMethod == 'M'){
        this.shippingcost = 0.50;
    }

    if( (this.weight >=9 && this.weight <= 16) && this.shippingMethod == 'A'){
        this.shippingcost = 3.00;
    }
    else if( (this.weight >= 9 && this.weight <= 16) && this.shippingMethod == 'T'){
        this.shippingcost = 2.35;
    }
    else if( (this.weight >= 9 && this.weight <= 16) && this.shippingMethod == 'M'){
        this.shippingcost = 1.50;
    }

    if( (this.weight > 17) && this.shippingMethod == 'A'){
        this.shippingcost = 4.50;
    }
    else if( (this.weight > 17) && this.shippingMethod == 'T'){
        this.shippingcost = 3.25;
    }
    else if( (this.weight > 17) && this.shippingMethod == 'M'){
        this.shippingcost = 2.15;
    }

}

public String toString(){
    return "Weight: " + this.weight + "\nShipping Method: " + 
            this.shippingMethod + "\nCost: " + this.shippingcost;
}
}

投保Package.java

package chap10q5;

/**
 *
 * @author james
 */
public class InsuredPackage extends Package {

public InsuredPackage(int weight, char shippingCost){
    if(super.shippingcost <= 1){
        super.shippingcost += 2.45;
    }
    else if( (super.shippingcost > 1.00) && (super.shippingcost <= 3.00) ){
        super.shippingcost += 3.95;
    }
    else if( super.shippingcost > 3 ){
        super.shippingcost += 5.55;
    }
}

@Override
public String toString(){
    return super.toString();
}
 }

使用Package.java（我的主要方法）：

package chap10q5;

/**
 *
 * @author james
 */
public class UsePackage {
    public static void main(String[] args){
        Package one = new Package(1, 'A');

        System.out.println(one);
    }
}

Answer 1

由于您在 Package 中没有默认构造函数，您需要在 InsuredPackage 构造函数中调用 Package 的构造函数之一。例如：

public InsuredPackage(int weight, char shippingMethod, double shippingCost) {
    super(weight, shippingMethod);

    ...
}

Answer 2

改变

public InsuredPackage(int weight, char shippingCost){
    if(super.shippingcost <= 1){
        super.shippingcost += 2.45;
    }
    else if( (super.shippingcost > 1.00) && (super.shippingcost <= 3.00) ){
        super.shippingcost += 3.95;
    }
    else if( super.shippingcost > 3 ){
        super.shippingcost += 5.55;
    }
}

至

public InsuredPackage(int weight, char shippingMethod){
    super(weight,shippingMethod);
    if(shippingcost <= 1){
        shippingcost += 2.45;
    }
    else if( (shippingcost > 1.00) && (shippingcost <= 3.00) ){
        shippingcost += 3.95;
    }
    else if(shippingcost > 3 ){
        shippingcost += 5.55;
    }
}

Answer 3

问题在于，当子 class 的构造函数不调用父 class 的构造函数时，编译器会在第一行调用默认构造函数，我的意思是 super()，但您没有在 Package class 中定义它，这就是错误。

Java extends inheritance 程序不工作？

Java extends inheritance Program not working?

java

inheritance

netbeans

Package.java

投保Package.java

使用Package.java（我的主要方法）：