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Question

在使用Serializable读取对象之后，我试图编辑对象数组。 该代码适用于我的对象的新实例，但是当我尝试编辑从文件读取的对象时，该代码给出了NullPointer异常。

public class ShoppingCenter implements Serializable{

// I cant write to file without transient
transient Scanner scan=new  Scanner (System.in);

private static final long serialVersionUID = 6529685098267757692L;


//This is the edit details method which will be used to modify the details
public void editDetails()
{
 System.out.println("The details are as follows:");
    System.out.println("*Name is "+ name);
    System.out.println("\t(1-Edit 2-Continue)");

    // *******This is where it gives the exception********
    if (scan.nextInt()==1)
    {System.out.println("\t Write the new value..");
        name=scan.next(); 
    System.out.println("Done..");}

    System.out.println("*Location is "+ location);
    System.out.println("\t(1-Edit 2-Continue)");
    if (scan.nextInt()==1)
    {System.out.println("\t Write the new value..");
        location=scan.next(); 
    System.out.println("Done..");}
}

这是堆栈跟踪。

java.lang.NullPointerException
at ShoppingCenter.editDetails(ShoppingCenter.java:40)
at Part3Main.searchObject(Part3Main.java:99)
at Part3Main.init(Part3Main.java:130)
at Part3Main.main(Part3Main.java:189)

这是我的司机。

       public void init(){
       readFile("shoppingCenter");
        }

        public void readFile(String name){
    try{
        FileInputStream fis = new FileInputStream(name);
        ObjectInputStream ois = new ObjectInputStream(fis);
        sc = (ShoppingCenter[]) ois.readObject();
        ois.close();
        System.out.println("The Object  was succesfully read from the file");
        //System.out.println(sc[1].toString());
        //System.out.println(sc.toString());
    }
    catch (Exception ex){
        ex.printStackTrace();
    }
}

一点帮助将不胜感激..谢谢..