Suppose we want to be able to create a Bank objectfrom a serialized version on a

Question

  Suppose we want to be able to create a Bank objectfrom a serialized version on a file (if one exists). Write amethod getBank which is consistent with the following client code.(A "client" of Bank is any software that uses Bank but which is nota member of Bank -- in our case it will be code in BankGui

String fileName ="/home/doug/my.bnk";
    Bank myB =Bank.getBank(fileName); //makes myB from serializeddata
    if(myB ==null){     //if file did not contain anobject of type Bank
    System.out.println("A NewBank");
    myB = newBank(fileName); //makes empty Bank that usesfilename

Explanation / Answer

Having a serialized version on file...it sounds as though youmight be able to use ObjectInputStreamand ObjectOutputStream. The onlything you have to do to Bank is add that it implements java.io.Serializable - which just notes that itcan be serialized. To read from a file: public Bank getBank(Stringfile) {    try    {       // create new input stream       ObjectInputStreamin=new ObjectInputStream(new FileInputStream(newFile(file)));       // read object       Bankbank=(Bank)in.readObject();       // close stream       in.close();       returnbank;    }    catch(IOExceptionex)    {       out.println("Cannotfind file.");    }    catch(ClassNotFoundExceptionex2)    {       out.println("Objectis not a bank.");    }       returnnull; } To write objects to the file: public void save(Bank bank, Stringfile) {    try    {       // create output       ObjectOutputStreamout=new ObjectOutputStream(new FileOutputStream(newFile(file)));       // write bank       out.writeObject(bank);       out.close();    }    catch(IOExceptionex)    {       out.println("Cannotfind file.");    } } }

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