I have a Java Class like this:
public class Employee {
String Name;
int Id;
int Age;
void setName(String tempVal) {
Name = tempVal;
System.out.println(Name);
System.out.println("\n");
}
void setId(int parseInt) {
Id = parseInt;
System.out.println(Id);
System.out.println("\n");
}
void setAge(int parseInt) {
Age = parseInt;
System.out.println(Age);
System.out.println("\n");
}
}
Now I want to parse a employees.xml file using SAXParser using the code in the link: http://totheriver.com/learn/xml/xmltutorial.html#5.2
The problem is when I am adding the tempEmp to the list and accessing the list to print its value in printData() method, the output is something like:
No of Employees '3'.
Employee#140de537
Employee#1c43882a
Employee#15a08be5
Now, how do I extract the name, age and id of the employee individually?
I guess you are adding the Employee object to the list and printing the objects directly from list.If you dont override the toString() method, it will call the toString() method of Object class(superclass of all class), which will be returing the classname#hashcode(hashcode of object).If you want to print some data from your class, you need to override toString() method in your class and return the format you require.
You have to implement a toString() method in the Employee class for it to be displayed correctly, something along these lines:
#Override
public String toString() {
return Id + " " + Name + " " + Age;
}
Also, remember that in Java attribute names should start with a lowercase character, not uppercase.
You want to add some getter methods.
You should also check out the code conventions for Java - some of your variables start with an uppercase letter where they should not.
To get each value individually, you need to add a few get methods
public String getName()
{
return Name;
}
public int getAge()
{
return Age;
}
public int getId()
{
return Id;
}
Related
Im doing an OOP assignment.. It has four classes Person, student and employee both extends person and instructor that extends employee. .
I have done Almost everything i could but i cant print out values using tostring method and Cant fill the array.I have used getter setter and all the constructor and methods are there still cant get any output. heres the person class and all the remain three classes have been made. plus the main file
abstract class Person
{
protected int Id;//"protected"Only child can use this
protected String Name;
public Person() {}
public Person(int id,String name)
{
this.Id=id;
this.Name=name;
}
public int getId()
{
return this.Id;
}
public void setId(int id)
{
this.Id=id;
}
public String getName()
{
return Name;
}
public void setName(String name)
{
this.Name=name;
}
public String toString()
{
return Id + Name + " is a student ";
}
public static int getMaxID()
{
return 0;
}
////////////////////////////////////////////////////////////////////////////////
public class Employee extends Person
{
protected double Salary;
protected String employeeName;
public Employee() {}
public Employee(double salary)
{
this.Salary=salary;
}
public Employee(String employeename)
{
this.employeeName=employeename;
}
public String getemployeeName()
{
return employeeName;
}
public void setemployeeName(String employeename)
{
this.employeeName=employeename;
}
public double getSalary()
{
return this.Salary;
}
public void setSalary(double salary)
{
this.Salary=salary;
}
public String toString()
{
return employeeName + " is an instructor earning a salary of " + Salary;
}
}
////////////////////////////////////////////////////////////////////////////////
public class Student extends Person
{
protected int teacherID;
protected String teacherName;
protected String studentName;
public Student() {}
public Student(int teacherid,String teachername)
{
this.teacherID=teacherid;
this.teacherName=teachername;
}
public Student(String studentname)
{
this.studentName=studentname;
}
public Student(String teachername, String studentname, Person[] person_array)
{
this.teacherName=teachername;
this.studentName=studentname;
}
public int getteacherID()
{
return this.teacherID;
}
public void setteacherID(int teacherid)
{
this.teacherID=teacherid;
}
public String getteacherName()
{
return teacherName;
}
public void setteacherName(String teachername)
{
this.teacherName=teachername;
}
public String toString()
{
return studentName + " is a student ";
}
}
////////////////////////////////////////////////////////////////////////////////
public class Instructor extends Employee
{
int[] studentID=new int[10];
protected String instructorName;
public Instructor(String instructorname)
{
this.instructorName=instructorname;
}
public Instructor(String instructorname, double salary)
{
this.instructorName=instructorname;
this.Salary=salary;
}
public double getSalary()
{
return Salary;
}
public void setSalary(int salary)
{
this.Salary=salary;
}
public String getinstructorName()
{
return instructorName;
}
public void setinstructorName(String instructorname)
{
this.instructorName=instructorname;
}
static void findStudents(Person[] person_array)
{
}
public String toString()
{
return instructorName + " is an instructor earning a salary of " + Salary;
}
}
////////////////////////////////////////////////////////////////////////////////
//CIS 459.23 Lab 2
//Due Oct 30 (Sunday)
//OSU wants you write some classes for their Personnel Record System. To make it simple,
//consider only 4 classes: Person, Employee, Instructor and Student. The following figure
//illustrates the relationship between these 4 classes. The Person class is the parent class of the
//Employee class and the Student class. The Employee class is the parent class of the Instructor
//class.
//The following are the tasks you need to complete for each of these classes.
// Create appropriate fields for each class. Necessary fields are listed. Add your own fields if
//needed. Some fields need to have appropriate constraint. Use your own way to make sure
//that these constraints are satisfied.
//o Person
//ID: int, starting from 1 and should be unique
//Name: String
//o Employee
//Salary: double and should not be negative
//o Student (For simplicity, assume that a student has at most 1 teacher)
//TeacherID: int. It’s his/her instructor's ID. 0 if no instructor is given
//TeacherName: String
//o Instructor:
// StudentIDArray: int array. An array of students’ IDs of this instructor. Set the
// array size to be 10, initially all 0s, assuming an instructor won’t have more than
// 10 students.
// All the above fields are private and only accessible through the access methods.
// A “toString()” method for each class to print out all the available information about the
// current object. In Person class “toString()” is declared as abstract.
// A static “findStudents(Person[] personArray)” method in the Instructor class to fill an
// instructor object’s students ID array, and the corresponding students’ TeacherID fields. See
// the test program for better understanding.
// Person should be declared as abstract class.
// Provide multiple constructors/methods if needed. Check the test.java program to see what
// constructors/methods are necessary and what actions they should do.
// If a class can use the parent class method and constructor, use “super” to call it to reduce the
// redundant code.
// Make sure this test.java program can work with your class.
// sample output. From this sample output, you’ll know what information you should print out
// for a specific object.
// NOTE: the sample output is not the unique output format of the test program. The real output
// format depends on how you design the toString() methods in each class. But make sure that your
// program will print out as much information about each object’s fields as possible, including the
// Person
// Instructor
// Employee Student
// inherited fields and the fields defined in its own class.
// HINT:
// o There is NO main method in any of these 4 classes
// o To make sure ID is unique across the objects, declare a static “LAST_ID” in the Person
// class.
// o Read descriptions in test.java VERY CAREFULLY for better
// understanding!
// Submit your Person.java, Emloyee.java, Student.java and Instructor.java files
// Appendix 1: Test Program
/*
* Lab 2 Program to test the Person, Employee, Student, and Instructor classes.
*/
public class Lab2_Test
{
public static void main(String[ ] args)
{
// uncommenting the following line should produce a compile error.
// This is for testing of an abstract class.
// Person p = new Person("George");
final int MAX_HEADCOUNT = 20;
Person[] person_array = new Person[MAX_HEADCOUNT];
// A student named Peter
person_array[0] = new Student("Peter");
// An instructor named Peter
person_array[1] = new Instructor("Peter");
// An instructor named Sandy and her salary
person_array[2] = new Instructor("Sandy", 25000);
// A janitor named Bob
person_array[3] = new Employee("Janitor Bob");
// A student named Tom and his instructor is Peter.
// The constructor needs to do three things:
// 1: sets this student’s “TeacherName” field to be “Peter”,
// 2: finds out the ID of the 1st instructor
// who exists in the person_array so far and named "Peter",
// and assign it to this student's “TeacherID” field.
// Set it to be 0 if no instructor named Peter is found in the person_array so far
// 3: records this student’s ID in the instructor’s StudentArray if such an instructor is found
// right after executing the following statement
// person_array[4].TeacherID = 2
// person_array[4].TeacherName = “Peter”
// person_array[1].StudentArray[0] = 5
person_array[4] = new Student("Tom", "Peter", person_array);
// A student named Maggie and her instructor is Susan
// right after executing the following statement
// person_array[5].TeacherID = 0
// person_array[5].TeacherName = “Susan”
person_array[5] = new Student("Maggie", "Susan", person_array);
// An instructor named Susan and her salary
person_array[6] = new Instructor("Susan", 40000);
// After all objects are created,
// instructors need to fill their students arrays,
// and some students need to fill their TeacherIDs now,
// since there may exist cases that when a Student object is created with instructor’s name,
// the corresponding Instructor object hasn’t been created and is not in the person_array.
// For example, person_array[6] is created after person_array[5].
// You need to record person_array[5]’s ID in person_array[6]’s studentArray field,
// and record person_array[6]’s ID in person_array[5]’s TeacherID field.
// Note: if there are more than one Instructor objects
// having the same names as a Student object’s TeacherName,
// it’ll always be the first one’s ID assigned to the Student object’s TeacherID
Instructor.findStudents(person_array);
System.out.println("ID and name of all personnel in the array");
for (int i = 0; i < Person.getMaxID(); i++)
{
System.out.println(person_array[i].getId() + ":" + person_array[i].toString());
}
}
You are trying to print using this:
for (int i = 0; i < Person.getMaxID(); i++)
{
System.out.println(person_array[i].getId() + ":" + person_array[i].toString());
}
But, the getMaxID() method in your Person class returns a hardcoded 0, so this loop will never iterate, and your print statement will never be reached.
EDIT: it makes no sense to even check for a maxId. Check against the length of the array:
for (int i = 0; i < person_array.length; i++)
{
System.out.println(person_array[i].getId() + ":" + person_array[i].toString());
}
I am trying to convert Java Object to JSON using Groovy JsonBuilder
Java POJO Class
public class Employee {
String name;
int age;
#Override
public String toString() {
return "Employee{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
}
Groovy Script
Employee employee = new Employee();
employee.name="Vinod"
employee.age=24
println new JsonBuilder( employee ).toPrettyString()
Output
{
}
I am not sure if I am using JsonBuilder incorrectly. Please help
Since you are using a Java POJO, you need to add the getters for the two properties you have, i.e., public String getName() and public String getAge().
The JsonBuilder leverages DefaultGroovyMethods.getProperties to get object properties. If you don't add the aforementioned getters, it does not find any properties and therefore the resulting JSON is empty.
So that:
Employee.java
public class Employee {
String name;
int age;
public String getName() {
return name;
}
public int getAge() {
return age;
}
#Override
public String toString() {
return String.format("Employee{name=%s, age=%d}", name, age);
}
}
If you use a POGO instead (Plain Old Groovy Object), getters are added by default for each property, so it works out of the box:
Trying to print out age and name of an Object using "get" method. However, my get method return type is string:
public String displayProfile() {
System.out.print(getName() + getAge());
Hence the error:
This method must return a result of type String
Here is my main method: if user enters '2' from the "menu" where (2 == profile) the program should display user's name and age.
Side note: To select "friends" from menu, user will enter '3' (3 = friends).
public static void main(String[] args) {
// Initializing Objects
People zac = new People();
zac.setName("zac");
zac.setAge(18);
People lisa = new People();
lisa.setName("lisa");
lisa.setAge(19);
// Zac be-friend LISA
zac.addFriend("lisa");
openApp();
if(optionSelected == 3)
{
System.out.println(zac.getFriend());
else if (optionSelected == 2) {
System.out.println(zac.displayProfile());
}
}
}
Being new to programming, I want to develop good programming practices, hence with this in mind; how would you display age and name of different type [int = age and string = name] from one method like i.e. public String displayProfile() OR is this completely wrong? Then what are the alternatives?
Additionally:
My getName() method:
// GET NAME
public String getName() {
return this.name;
}
My setName() method:
// SET NAME
public void setName(String name) {
this.name = name;
}
My getAge() method:
// GET AGE
public int getAge() {
return this.age;
}
My setAge() method:
// SET AGE
public void setAge(int age) {
age = this.age;
}
You can use String.format() with format specifiers (%s, %d, %f...)
public static String displayProfile()
{
return String.format("%s %d", "StackOverflow", 6);
}
Note the return statement. It's totally different than System.out.print(...)
Also, the body of setAge() method, should look like:
this.age = age;
since you want to assign the age passed as parameter to the member this.age
My professor just went over mutable and immutable, and gave us this coding exercise to complete.
1) Create a Customer object called customer with initial values of 1 and "Cust1"
respectively.
2) Display the customer object to the screen using the toString() method.
3) Create a String object reference called name and assign to it the customer's name.
4) Assign the value "Bo Beep" to the object reference name.
5) Display the customer object to the screen using the toString() method.
The output should look like this.
Customer{id=1, name=Cust1}
Customer{id=1, name=Cust1}
I currently have 2 seperate classes, here they are. I'm not sure whether I'm doing it correctly, I think I have done the first 2 right, but I'm not sure about 3-5.
Any input is helpful, thanks!
Here's my main class,
package hw01;
public class Main {
static Customer customer = new Customer(1, "cust1");
static Customer name = new Customer(1, "Bo Peep");
public static void main(String[] args) {
System.out.println(customer);
System.out.print(customer);
}
}
And here's my Customer class.
package hw01;
public class Customer {
private int id;
private String name;
public Customer() {
}
public Customer(int id, String name) {
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
#Override
public String toString() {
return "Customer{" + "id=" + id + ", name=" + name + '}';
}
}
Sounds like for #3 it should be something like this:
String name = customer.getName();
and then #4 would be:
name = "Bo Peep";
The goal of the exercise I think is to demonstrate that even though name and customer.name reference the same String object, since a String is immutable when you set name = "Bo Peep"; you're not changing the actual String object but instead creating and referencing a new String object. If the String were mutable then printing the customer the 2nd time would display the name "Bo Peep".
I want to add a toString method in the Item class that returns the title of the item in there.
I have need make sure that the toString method in the DVD class calls the toString method in Item so that it can return a string that contains both the title and the director.
Item is the superclass and DVD is the subclass.
public class Item
{
private String title;
private int playingTime;
private boolean gotIt;
private String comment;
public Item(String theTitle, int time)
{
title = theTitle;
playingTime = time;
gotIt = false;
comment = "<no comment>";
}
// Getters and setters omitted
public void print()
{
System.out.print(title + " (" + playingTime + " mins)");
if(gotIt) {
System.out.println("*");
} else {
System.out.println();
}
System.out.println(" " + comment);
}
}
public class DVD extends Item
{
private String director;
public DVD(String theTitle, String theDirector, int time)
{
super(theTitle, time);
director = theDirector;
}
// Getters and setters omitted
public void print()
{
System.out.println(" director: " + director);
}
}
Item toString:
public String toString()
{
return title;
}
DVD toString:
public String toString()
{
return super.toString() + " director: " + director;
}
Also, I don't know what you're trying to do with this but I would put those print() methods in these classes.
You will be better of returning the string representation and printing it somewhere else (with this you can test this class without mocking System.out)
Cheers
A toString method is already defined in each Java class (it inherits the toString of Object). But it will return a practically meaningless value (AFAIR, the internal address/id of the instance within the JDK - I might be wrong).
What you need to do is to override that method and make it return a String that is the title of the Item. For the DVD class, you have to override toString and make it a string made up of the concatenation of the title and director.
For the Item class, your method should look something like this:
public String toString(){
return this.title;
}
You should be able to use the same idea to implement toString for DVD.