空指针异常在调用getter函数时发生。请尽快提供帮助。我最后写了错误。我还提到了发生错误的那一行。不过,部分输出是正确的。
import java.util.Scanner;
public class Solution
{
public static void main(String args[] ) throws Exception
{
/* Do not alter code in main method */
Shirt[] shirts = new Shirt[5];
Scanner sc = new Scanner(System.in);
for(int i = 0;i<5;i++)
{
int tag = sc.nextInt();sc.nextLine();
String brand = sc.nextLine();
double price = sc.nextDouble();sc.nextLine();
char g = sc.nextLine().charAt(0);
shirts[i] = new Shirt(tag,brand,price,g);
}
double price = sc.nextDouble();
for(Shirt s: shirts)
{
System.out.println(getDiscountPrice(s));
}
Shirt[] result = getShirtWithMoreThanSpecificPrice(shirts,price);
for(Shirt s: result)
{
System.out.println(s.getTag()+" "+s.getPrice()+" "+s.getBrand());//This is where the exception occurs
}
}
public static double getDiscountPrice(Shirt s)
{
double p;
if(s.g=='m')
{
p=s.price-((0.1*s.price));
return p;
}
if(s.g=='f')
{
p=s.price-((0.2*s.price));
return p;
}
if(s.g=='u')
{
p=s.price-((0.3*s.price));
return p;
}
return 0.0;
}
public static Shirt[] getShirtWithMoreThanSpecificPrice(Shirt[] shirts,double price)
{
Shirt[] sh=new Shirt[5];
for(int i=0;i<5;i++)
{
if(shirts[i].price>price)
{
sh[i]=shirts[i];
}
}
return sh;
}
}
class Shirt
{
//define the class as per details shared in the question
int tag;
String brand;
double price;
char g;
public Shirt(int tag,String brand,double price,char g)
{
this.brand=brand;
this.g=g;
this.price=price;
this.tag=tag;
}
public void setG(char g)
{
this.g = g;
}
public void setTag(int tag)
{
this.tag = tag;
}
public void setBrand(String brand)
{
this.brand = brand;
}
public void setPrice(double price)
{
this.price = price;
}
public int getTag()
{
return tag;
}
public double getPrice()
{
return price;
}
public String getBrand()
{
return brand;
}
public char getG()
{
return g;
}
}
错误:
线程“主”中的异常java.lang.NullPointerExceptionSolution.main(Solution.java:32
错误发生在第32行。我试图初始化变量。没有一个是成功的。
[使用getShirtWithMoreThanSpecificPrice
在Shirt[] sh = new Shirt[5]
中分配新数组时,将使用五个null
值对其进行初始化。
然后分配元素,但仅在有条件的情况下:if (shirts[i].price > price) sh[i] = shirts[i];
。因此,某些值可能仍然是null
。在main
中循环访问此数组时,必须在for (Shirt s: result)
中检查s
是否为null
。可能会发生,这就是这里发生的事情。
现在,最好只返回一个非空值的数组,也就是返回其值为shirts[i].price > price
的衬衫。您可以改用List
(仅附加非空值)或Arrays.copyOf
(如果您设法在数组sh
的开头存储非空值,且不带孔)。
尝试用以下代码替换您的for循环代码:
for (Shirt s : result) {
if(s != null) {
System.out.println(s.getTag() + " " + s.getPrice() + " " + s.getBrand());// This is where the exception
}
// occurs
}
当您初始化数组而不分配值时,它的默认值为null
。