DESCRIPTION:
In my program, users are asked to input some values. The values get stored into an ArrayList so that I can print them out. Now the problem with this one is all data is lost once I terminate the program. That's why I have decided to store those arrayList object into file and and read them from there.
PROBLEM/QUESTION:
I have created all the related methods to write and read file. But it seems that no objects are written and read in file.The class I am mainly concerned about is ReadWrite.
Working code:
ReadWrite:
public void writeFile(List<PersonInfo> information) {
try {
FileOutputStream fos = new FileOutputStream("C:\\Users\\Documents\\NetBeansProjects\\BankFile4.txt");
ObjectOutputStream os = new ObjectOutputStream(fos);
os.writeObject(information);
os.flush();
fos.close();
os.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public List<PersonInfo> readFile() {
List<PersonInfo> dataFromFile=null;
try {
FileInputStream fis = new FileInputStream("C:\\Users\\Documents\\NetBeansProjects\\BankFile4.txt");
ObjectInputStream is = new ObjectInputStream(fis);
dataFromFile=(List<PersonInfo>)is.readObject();
fis.close();
is.close();
//return readFile();
} catch (Exception e) {
e.printStackTrace();
}
return dataFromFile;
}
AboutPerson:
Scanner input = new Scanner(System.in);
List<PersonInfo> info = new ArrayList<PersonInfo>();
List<PersonInfo> info2 = new ArrayList<PersonInfo>();
ReadWrite rw=new ReadWrite();
rw.writeFile(info);
info2=rw.readFile();
while (true) {
System.out.println("\n");
System.out.println("1. Input personal info\n"
+ "2. Print them out\n"
+ "*************"
+ "*************");
option1 = input.nextInt();
input.nextLine();
switch (option1) {
case 1:
PersonInfo personInfo = new PersonInfo();
//take the input
System.out.println("Enter a name: ");
personInfo.setName(input.nextLine());
System.out.println("Give ID: ");
personInfo.setId(input.nextInt());
System.out.println("Input credit: ");
personInfo.setCredit(input.nextDouble());
//addint them up
info.add(personInfo);
break;
case 2:
//display them
System.out.println("");
System.out.println("Name\t\tID\t\tCredit");
for (PersonInfo pInfo : info) {
System.out.println(pInfo);
}
System.out.println("\t\t.............\n"
+ "\t\t.............");
break;
}
}
PersonInfo:
........
........
public PersonInfo() {
this.name = null;
this.id = 0;
this.credit = 0;
}
public void setName(String name) {
this.name = name;
}
.........
.........
package com.collection;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
class PersonInfo implements Serializable{
private String name;
private int id;
private double credit;
public PersonInfo(){}
public PersonInfo(String name,int id,int credit)
{
this.name=name;
this.id=id;
this.credit=credit;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public double getCredit() {
return credit;
}
public void setCredit(double credit) {
this.credit = credit;
}
}
class ReadWrite
{
public void writeFile(List<PersonInfo> information){
try {
FileOutputStream fos = new FileOutputStream("/home/mohammad.sadik/TestReadWrite.txt");
ObjectOutputStream os = new ObjectOutputStream(fos);
os.writeObject(information);
os.flush();
fos.close();
os.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public List<PersonInfo> readFile() {
List<PersonInfo> dataFromFile=null;
try {
FileInputStream fis = new FileInputStream("/home/mohammad.sadik/TestReadWrite.txt");
ObjectInputStream is = new ObjectInputStream(fis);
dataFromFile=(List<PersonInfo>)is.readObject();
fis.close();
is.close();
//return readFile();
} catch (Exception e) {
e.printStackTrace();
}
return dataFromFile;
}
}
public class AboutPerson {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
List<PersonInfo> info = new ArrayList<PersonInfo>();
List<PersonInfo> info2 = new ArrayList<PersonInfo>();
ReadWrite rw=new ReadWrite();
while (true) {
System.out.println("\n");
System.out.println("1. Input personal info\n"
+ "2. Print them out\n"
+ "*************"
+ "*************");
int option1 = input.nextInt();
input.nextLine();
switch (option1) {
case 1:
PersonInfo personInfo = new PersonInfo();
//take the input
System.out.println("Enter a name: ");
personInfo.setName(input.nextLine());
System.out.println("Give ID: ");
personInfo.setId(input.nextInt());
System.out.println("Input credit: ");
personInfo.setCredit(input.nextDouble());
//addint them up
info.add(personInfo);
rw.writeFile(info);
break;
case 2:
//display them
info2=rw.readFile();
System.out.println("");
System.out.println("Name\t\tID\t\tCredit");
for (PersonInfo pinfo : info2) {
System.out.println(pinfo.getName()+"\t\t"+pinfo.getId()+"\t\t"+pinfo.getCredit());
}
System.out.println("\t\t.............\n"
+ "\t\t.............");
break;
}
}
}
}
Please implement serializable interface in PersonInf class.When u going to write object into file then u need to implement serializable interface other wise u will get exception like this: java.io.NotSerializableException: com.collection.PersonInfo