search specific data using ObjectInputStream

[lee ji eun]

public static void searchFile(String regNum)throws IOException, ClassNotFoundException{
		String foundData = "";
		File file = new File("car.bin");
			if(file.exists()){
				ObjectInputStream ois2 = new ObjectInputStream(new FileInputStream("car.bin"));
				Car.carList = (Car[])ois2.readObject();
				for(int i=0;i<100;i++){
				    String data = ? //What should i put here 
					if(data.contains(regNum)){
						foundData = data;
						break;
					}
				}
				if (foundData == ""){
					System.out.println("Cannot Find Any Record ! Please Back to the Main Menu to Register the Customer !");
				}
				else{
					System.out.println("Found Record !");
				}
			}
	}

[Carey Brown]

On line 6 you have a Car list and a Car array, which is it? How was Car list/array written to the file in the first place?

We'd need to see the source for Car and the source for where the data was being written.

[lee ji eun]

import java.io.FileNotFoundException;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.FileOutputStream;
import java.io.EOFException;
import java.util.Scanner;
import java.io.File;
import java.io.*;

public class Car implements java.io.Serializable{
	private String carId;
	private String regNum;
	private String model;
	private String color;
	private Customer owner;
	private static int nextId = 0;
	private static Car[] carList = new Car[100]; 
	
	public Car(String regNum, String model, String color, Customer owner){
		this.regNum = regNum;
		this.model = model;
		this.color = color;
		this.owner = owner;
		this.carId = String.format("V%04d", ++nextId);
		carList[nextId-1] = this;
	}
	
	public static void readFile()throws IOException, ClassNotFoundException{
		File file = new File("car.bin");
			if(file.exists()){
				ObjectInputStream ois2 = new ObjectInputStream(new FileInputStream("car.bin"));
				Car.carList = (Car[])ois2.readObject();
				for(int i=0;i<100;i++){
					if(Car.carList[i] == null){
						Car.nextId = i;
						break;
					}
				}
			}
	}
	
	public static void searchFile(String regNum)throws IOException, ClassNotFoundException{
		String foundData = "";
		File file = new File("car.bin");
			if(file.exists()){
				ObjectInputStream ois2 = new ObjectInputStream(new FileInputStream("car.bin"));
				Car.carList = (Car[])ois2.readObject();
				for(int i=0;i<100;i++){
				    String data = ? //What should i put here 
					if(data.contains(regNum)){
						foundData = data;
						break;
					}
				}
				if (foundData == ""){
					System.out.println("Cannot Find Any Record ! Please Back to the Main Menu to Register the Customer !");
				}
				else{
					System.out.println("Found Record !");
				}
			}
	}
	
	public static String getNextCarId(){
		return String.format("V%04d", nextId+1);
	} 
	
	public static Car[] getCarList(){
		return carList;
	}

	public static void displayAllCars(){
		for (int i = 0; i<nextId; i++){
			System.out.println(carList[i]);
		}
	}
	
	public void setRegNum(String regNum){
		this.regNum = regNum;
	}
	
	public void setModel(String model){
		this.model = model;
	}
	
	public void setColor(String color){
		this.color = color;
	}
	
	public String getRegNum(){
		return regNum;
	}
	
	public String getModel(){
		return model;
	}
	
	public String getColor(){
		return color;
	}
	
	public String getCarId(){
		return carId;
	}
	
	public Customer getOwner(){
		return owner;
	}
		
	public String toString(){
		return String.format("%s %s %s %s %s",carId,regNum,model,color,owner);
	}
	
}

//this is my car class

[Carey Brown]

                Car.carList = (Car[])ois2.readObject();
                for(int i=0;i<100;i++){
                    String data = ? //What should i put here 

You've got an array and and index into the array so data should be the i'th element in the array followed by getRegNum().

[Carey Brown]

Where is your writeFile() method?

[Carey Brown]

I would think you'd want to search the static Car[] in the class and not the file. If someone wants to search the file then they should call readFile() followed by a call to search(). Search should not be responsible for reading as well. The way you have it there is the potential with search to populate the array without populating nextId.

[Carey Brown]

Carey Brown wrote:

                Car.carList = (Car[])ois2.readObject();
                for(int i=0;i<100;i++){
                    String data = ? //What should i put here 

You've got an array and and index into the array so data should be the i'th element in the array followed by getRegNum().

This will barf when the i'th element is null.

[lee ji eun]

so i should write a method that search in the array ?

[Carey Brown]

lee ji eun wrote:so i should write a method that search in the array ?

Yes, and avoid nulls.

                for(int i=0;i<nextId;i++){
                    Car car = carList[i];

[lee ji eun]

sorry for the late reply. i will try it soon. thank you so much

[lee ji eun]

public static void searchCars(String regNum){
		for (int i = 0; i<nextId; i++){
			if (regNum != null){
				 Car car = carList[i];
				 System.out.println(carList[i]);
			}	
		}
		
	}

//this is what i do but still cannot output anything

[lee ji eun]

import java.io.FileNotFoundException;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.FileOutputStream;
import java.util.Scanner;
import java.util.Date;
import java.io.File;
import java.io.*;

public class CreateNewAppointment{
	public static void main(String[]args) throws IOException, ClassNotFoundException{
		Scanner input = new Scanner(System.in);
			
		Service[] serTypeArr = {new Service("Repair",600.00,"Mechanical and bodywork repair"),
								new Service("Repaint",200.00,"Protection and Decoration purposes"), 
								new Service("Wax&Polish",100.00,"Polish to add a layer of shine"),
								new Service("Maintenance",500.00,"Maintain Brakes and Tranmissions"),
								new Service("Free Inspection",0.00,"Free maintenance only for national day")};
								
		TimeSlot[] timeSlotArr = {new TimeSlot(new Date(),"10:00am","10:30am"),
								  new TimeSlot(new Date(),"10:30am","11:00am"),
								  new TimeSlot(new Date(),"11:00am","11:30am"),
								  new TimeSlot(new Date(),"11:30am","12:00pm"),
								  new TimeSlot(new Date(),"12:00pm","12:30pm"),
								  new TimeSlot(new Date(),"12:30pm","13:00pm"),
								  new TimeSlot(new Date(),"13:30pm","14:00pm"),
								  new TimeSlot(new Date(),"14:00pm","14:30pm"),
								  new TimeSlot(new Date(),"14:30pm","15:00pm"),
								  new TimeSlot(new Date(),"15:00pm","15:30pm"),
								  new TimeSlot(new Date(),"15:30pm","16:00pm"),
								  new TimeSlot(new Date(),"16:00pm","16:30pm"),
								  new TimeSlot(new Date(),"16:30pm","17:00pm")};
								  
		//Appointment.readFile();
		
		
		//ObjectOutputStream oos3 = new ObjectOutputStream(new FileOutputStream("appointment.bin",true)); //write into the file
		
		
		System.out.println("Appointment ID : "+Appointment.getNextAppointmentId()); 
			
		System.out.print("Car Registration Number : ");
		String regNum= input.next();
		
		Car.searchCars(regNum); //this is where i pass my value inside to search my element
			
		System.out.printf("\n\nService Types:\n");
		System.out.printf("%s %15s %10s %35s\n","No.","Service","Price","Service Description");
			
		for (int j=0; j<serTypeArr.length; j++){
			System.out.printf("%d %18s %10.2f %40s\n",(j+1),serTypeArr[j].getSerName(),serTypeArr[j].getSerPrice(),serTypeArr[j].getSerDesc());
		}
					
		System.out.print("Select the Servie Type[1..."+serTypeArr.length+"]:");
		int selection = input.nextInt();
		Service serType = serTypeArr[selection-1];
							
			System.out.println("The available time slot");
			System.out.println("------------------------");
			System.out.printf("%s %10s %25s %15s\n","No.","Date","Start Time","End Time");
			System.out.println("-----------------------------------------------------------");
				
			for (int i=0; i<timeSlotArr.length; i++){
				System.out.printf("%d\t\t%tB %<te, %<tY %15s %16s\n",(i+1),timeSlotArr[i].getDate(),timeSlotArr[i].getStartTime(),timeSlotArr[i].getEndTime());
			}
				
			System.out.print("Select the Time[1..."+timeSlotArr.length+"]:");
			int option = input.nextInt();
			TimeSlot time = timeSlotArr[option-1];
				
			//Appointment appoint = new Appointment(carDetail, serType, time);
				
			//System.out.println("The appointment is created !");
			
			//System.out.println(appoint.toString());
			
			//oos3.writeObject(Appointment.getAppointmentList());
			//oos3.flush();			
			//oos3.close();
		}		 
}

// this is my main program

[Carey Brown]

lee ji eun wrote:

public static void searchCars(String regNum){
		for (int i = 0; i<nextId; i++){
			if (regNum != null){
				 Car car = carList[i];
				 System.out.println(carList[i]);
			}	
		}
		
	}

Line 3: Could "regNum" be null? possible but not likely. Even if it is null, checking it 100 times inside the loop isn't going to make a difference.

On the other hand (line 4) could carList[i] be null? Absolutely, even guaranteed.

"car" is a reference to a Car object. "carList" is an array of references to Cars. So after line 4, "car" now contains the same reference as carList[i]. You can test "car" to see if it's null and you can print "car" on line 5.

[Al Hobbs]

You are trying to find the regNum so you would loop through the array, and check if the car value's regNum matches value you passed in.

[lee ji eun]

yes, but i cannot output anything

[Al Hobbs]

Have you tried debugging the app to see if you can find the problem?

[Al Hobbs]

What exactly are you trying to do?

[lee ji eun]

no i dunno how to do that

[Al Hobbs]

What IDE are you using?

[lee ji eun]

jcreator

[Al Hobbs]

Which version are you using because LE doesn't have a debugger apparently.

[lee ji eun]

JDK version 1.8.0_92

[Dave Tolls]

If debugging is a problem why not add System.out.println() calls, printing out values so you can at least see what the flow is, and what value everything has.

[Campbell Ritchie]

Al Hobbs wrote:Which version are you using

I presume you meant which version o JCreator not of the JDK.

. . . LE doesn't have a debugger apparently.

Does that mean JCreator Lite?

[Al Hobbs]

It might be lite.   Either way i think learning how to use a debugger is worth it over just using print statements.  Still not really sure what hes trying to do with the code.

[Junilu Lacar]

Al Hobbs wrote:It might be lite.   Either way i think learning how to use a debugger is worth it over just using print statements.

There is one school of thought that considers skills with a debugger a Bad Thing. They prefer learning how to write unit tests that will fail when there's a bug in your code. Also, learning how to write tests up front so that you have a failing test if your code is missing some kind of functionality (you could also think of missing functionality as a "bug")

[Al Hobbs]

How many tests are good to write?  Like one per public method or what is a good gauge to know if you have enough or too many?

[Knute Snortum]

At least one per public method.  You should test all sorts of input and output.

[Knute Snortum]

Here's a test of one method from an old project of mine.  Notice that it tests all sorts of behavior:

	@Test
	public void testValidateEditorPass() {
		setVariables();
		when( editorDaoMock.idByUsername( editor.getUsername() ) )
				.thenReturn( EDITOR_ID );
		when( editorDaoMock.read( EDITOR_ID ) ).thenReturn( editor );
		bindingResult.setErrors( false );
		String menu = lc.validateEditor( editor, bindingResult, modelMock );
		verify( editorDaoMock ).idByUsername( anyString() );
		verify( editorDaoMock ).read( anyInt() );
		verify( modelMock ).addAttribute( anyString(), any( Editor.class ) );
		verify( sessionInfo ).setEditor( any( Editor.class ) );
		assertTrue( "login/success".equals( menu ) );
	}

[Carey Brown]

public static void searchCars( String regNum ) {
    // print everything that DOES NOT change in the loop
    System.out.println( "regNum=" + regNum );
    System.out.println( "carList.length=" + carList.length );
    System.out.println( "nextId=" + nextId );
    for( int i = 0 ; i < nextId ; i++ ) {
        Car car = carList[i];
        // print everything that DOES change in the loop
        System.out.println( i + ": " + car );
    }	
}