Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 8 years ago.
Improve this question
Hello I have the following problem: I want to create an arraylist and want to add some items.
But somehow the .add Method is not there.
import java.util.ArrayList;
public class Chairing{
private int numbers;
ArrayList<Chairs>myList = new ArrayList<Chairs>();
myList.add(5,new Chairset("10"));
}
public class Chair{
int price;
String info;
public Chair(int price, Chairset c){
this.price = price;
info = c.getInfo();
}
}
public class Chairset{
String info;
public Chairset(String id){
id = info;
}
}
For some Reasons I can't add something in my new ArrayList. The constructor for Chair needs a price and an object Chairset. Chairset needs an id.
The problem is your classes have no common type, the tightest generic bound the list can have would be Object. Either use a marker interface, or notice the similarity between Chair and Chairset and have one extend the other - giving them a common type.
Also note that the line in your code where you add to the list is not in a legal location - it must be within a method.
Try this:
public class Chairing {
private int numbers;
List<Chairset> myList = new ArrayList<Chairset>();
public void someMethod() {
myList.add(5,new Chairset("10"));
}
}
public class Chair extends Chairset {
int price;
public Chair(int price, Chairset c){
super(c.getInfo());
this.price = price;
}
}
public class Chairset {
String info;
public Chairset(String id){
id = info;
}
}
Related
Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 5 years ago.
Improve this question
I have java class adapter and this is error (Groceries b : getData()), because object cannot be converted to Groceries.java, if i change to (Object b : getData()) i can't call a method b.getProduct().getSn() from Groceries.java
DataAdapter.java
public Groceries getBelBySN(String sn) {
Groceries pp = null;
for (Groceries b : getData()) {
if (b.getProduct().getSn().equals(sn)) {
pp = b;
break;
}
}
return pp;
}
public void updateTotal() {
long jumlah = 0;
for (Groceries b : getData()) {
jumlah = jumlah + (b.getProduct().getHarga() * b.getQuantity());
}
total = jumlah;
}
This is Groceries.java that i call on adapter
public class Groceries {
protected Product product;
protected int quantity;
public Groceries(Product product, int quantity) {
this.product = product;
this.quantity = quantity;
}
public void setProduct(Product product) {
this.product = product;
}
public Product getProduct() {
return product;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
public int getQuantity() {
return quantity;
}
It seems like getData() doesnt return a Groceries object. Could you provide the implementation for it, please.
Every object in Java inheritates from Object.class that's why you can cast to it without any problems. The Object.class doesn't have any of your Groceries functions, that's why you get an error calling them. You should probably read a good book about OOP and OOP in Java first.
EDIT:
I don't know how your getData() function looks like, but it should be something like this to make the advanced for loop work:
ArrayList<Groceries> myGroceries = new ArrayList<Groceries>();
public ArrayList<Groceries> getData(){
return myGroceries;
}
Then your loop should run just fine.
for (Groceries b : getData()) {
// Do stuff
}
Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 8 years ago.
Improve this question
E.g.
[{
'name': 'Foo',
'distance': 2
},{
'name': 'Bar'
}]
This will parsed into a list of objects of this class:
class City {
public String name;
public int distance;
}
However for Bar the city object will not have the distance attribute. Can I check for types like I would check for objects? Like:
if(city.distance)
How can I check if distance is set?
Gson gson = new Gson();
City city = gson.fromJson(json, City.class);
Custom parse classes are allowed with GSON. Just use Integer instead of int and check for null value.
Remember that you have to create a City class with a void constructor:
public class City {
public Integer distance;
public String name;
public City() {/*void constructor*/}
public Integer getDistance() {
return distance;
}
public void setDistance(Integer distance) {
this.distance = distance;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Check for null using city.getDistance()==null
You can use an Integer instead of an int, and check if it is null. The same can be made for other atributes, use a class instead of a raw type.
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Questions asking for code must demonstrate a minimal understanding of the problem being solved. Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist
Closed 9 years ago.
Improve this question
I have array list of type Warehouse. Each Warehouse has a stock amount. The method getStock() returns the stock level.
I have an ArrayList of Warehouse. I want to get the stock of each warehouse in the list and add it to a list.
My code:
import java.util.*;
public class Warehouses {
ArrayList<Warehouse> warehouses = new ArrayList<Warehouse>();
public Warehouses() {
warehouses.add(new Warehouse("W1", 20, "RM13 8BB"));
warehouses.add(new Warehouse("W2", 28, "RM13 8BB"));
warehouses.add(new Warehouse("W3", 17, "RM13 8BB"));
}
public void stockList() {
ArrayList<Integer> stockList = new ArrayList<Integer>();
for(Warehouse warehouse : warehouses) {
Integer stock = warehouse.getStock();
System.out.println(stock);
}
}
}
class Warehouse
{
// instance variables - replace the example below with your own
private String warehouseID;
private int warehouseStock;
private String location;
/**
* Constructor for objects of class Warehouse
*/
public Warehouse(String warehouseID, int warehouseStock, String location)
{
// initialise instance variables
warehouseID = warehouseID;
warehouseStock = warehouseStock;
location = location;
}
public int getStock(){
return warehouseStock;
}
public String getLocation() {
return location;
}
}
When I call stockList() I just get three empty values. What is wrong here?
Thanks
Assign the constructor arguments of Warehouse to the class member variables rather than re-assigning the local variables themselves
public Warehouse(String warehouseID, int warehouseStock, String location) {
this.warehouseID = warehouseID;
this.warehouseStock = warehouseStock;
this.location = location;
}
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Questions asking for code must demonstrate a minimal understanding of the problem being solved. Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist
Closed 9 years ago.
Improve this question
class Course {
private String courseName;
ArrayList<String> students = new ArrayList<>();
private int numberOfStudents;
public Course(String courseName) {
this.courseName = courseName;
}
public void addStudent(String student) {
students[numberOfStudents] = student;//<-- Line 15
numberOfStudents++;
}
public ArrayList getStudents() {
return students;
}
public int getNumberOfStudents() {
return numberOfStudents;
}
public String getCourseName() {
return courseName;
}
}
Line 15 I am getting error "Array required, but ArrayList found.
I am unsure what to do here as I am new to strings and such.
students is declared as an ArrayList. This notation
students[numberOfStudents] = student;
only works for array types. You should use
students.add(student);
Please read the javadoc for ArrayList.
You also don't need to keep a field to hold the number of students, as
students.size();
will give you that.
If you want to use ArrrayList in your program:
public void addStudent(String student) {
students.add(student);
}
public int getNumberOfStudents() {
return students.length();
}
Also then you do not require numberOfStudents variable
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Closed 9 years ago.
Questions concerning problems with code you've written must describe the specific problem — and include valid code to reproduce it — in the question itself. See SSCCE.org for guidance.
Questions must demonstrate a minimal understanding of the problem being solved. Tell us what you've tried to do, why it didn't work, and how it should work. See also: Stack Overflow question checklist
Improve this question
I'm new to Java. I want to create Java Object with test data and access the object from remote class. I created this object:
public class TestAgentData
{
public TestAgentDataObj tad;
public class TestAgentDataObj
{
public int agentId = 1234;
public String agentName = "AgentName";
public String description = "AgentDscription";
public TestAgentDataObj(int agentId, String agentName, String description)
{
this.agentId = agentId;
this.agentName = agentName;
this.description = description;
}
public int getAgentId()
{
return agentId;
}
public void setAgentId(int agentId)
{
this.agentId = agentId;
}
public String getAgentName()
{
return agentName;
}
public void setAgentName(String agentName)
{
this.agentName = agentName;
}
public String getDescription()
{
return description;
}
public void setDescription(String description)
{
this.description = description;
}
}
public TestAgentDataObj getTad()
{
return tad;
}
public void setTad(TestAgentDataObj tad)
{
this.tad = tad;
}
}
I tried to access the object from remote class:
Object eded = new TestAgentData.getTad();
But I get error in Netbeans. Can you tell what is the proper way to access data in a Java Object?
I think you need a better understanding about java. There are big errors in this.
You cannot way you create your object is wrong its new TestAgentData()
You can't call getTad() from an object of type Object because there is no getTad() method defined in Object class. Rather do the following
TestAgentDataObj obj=new TestAgentData().new TestAgentDataObj();
TestAgentData eded = new TestAgentData();
eded.setTad(obj);
TestAgentDataObj result=eded.getTad();