Edited the getTypeString method in the Flowers class now I just get the pointer to the object
I'm working on a project for one of my classes. I haven't worked with HashMap before and I need to use one. In this java class I'm trying to print out the full description that I have set. But it wont print the HashMap value from the key. I have tried to use some code from my book, but with no luck.
This is the class that is calling the class that has the HashMap:
public class Garden
{
private Gardener gardener;
private Tools tools;
private Flowers flowers;
/**
* Constructor for objects of class Garden
*/
public Garden()
{
gardener = new Gardener();
tools = new Tools();
Flowers rose;
rose = new Flowers("a beautiful red flower");
rose.setFlower("red", rose);
System.out.println(rose.fullDescription());
}
}
Edited the getTypeString method
This is the class that is using the HashMap:
import java.util.Set;
import java.util.HashMap;
public class Flowers
{
private String fDescription;
private HashMap<String, Flowers> flowers;
/**
* Constructor for objects of class Flowers
*/
public Flowers(String fDescription)
{
this.fDescription = fDescription;
flowers = new HashMap<String, Flowers>();
}
public void setFlower(String color, Flowers type)
{
flowers.put(color, type);
}
public String flowerDescription()
{
return fDescription;
}
public String fullDescription()
{
return "The "+ getTypeString() + " is " + fDescription;
}
private String getTypeString()
{
String des = "";
Collection<Flowers> vals = flowers.values();
for(Flowers f : vals){
des += f;
}
return des;
}
}
The problem, I think, is in the getTypeString() function. Can anyone point me in the right direction?
Edit
I removed the getTypeString method and edited the fullDescription method:
public String fullDescription()
{
return "The "+ type + " is " + fDescription;
}
now I'm trying to get the 'HashMap' to print the objects like so:
"Flower [type= type, description= Description "]"
using thes methods:
public static void printHashMap()
{
System.out.println("hashmap: " + flowers);
}
#Override
public String toString()
{
return "Flower [type=" + type + ", description=" + fDescription ]";
}
From your post, what I have understood is that you want to print the description of flowers. So I think you can try something like:
private String getTypeString(){
String des = "";
Collection<String> vals = flowers.values();
for(String f : vals){
des = des + f.flowerDescription();
}
return des;
}
Override the toString method in your class
Declare a toString method with the following modifiers and return type:
#Override
public String toString() {
return this.fDescription;
}
Implement the method so that it returns a string.
Related
In the image above, the contents of the arraylist is printed using println. I want a similar functionality for my created objects without using toString() function in java
please tell me how can i do that
To facilitate the answer, I added a CustomClazz with toString method and two fields(firstField, secondField) to be printed. The code uses both the toString method and Stream-> println of each object;
import java.util.ArrayList;
import java.util.Arrays;
public class MyClass {
public static void main(String args[]) {
ArrayList<CustomClazz> list = new ArrayList<>();
list.add(new CustomClazz("custom1","class1"));
list.add(new CustomClazz("custom2","class2"));
list.add(new CustomClazz("custom3","class3"));
//Stream that accesses and concatenates each field of custom class.. notice the bad concatenation "+"
list.stream().map(customClass -> customClass.getFirstField()+ customClass.getSecondField()).forEach(System.out::println);
System.out.println();
System.out.println();
//Option that uses the toString method of customClazz.
System.out.println(Arrays.toString(list.toArray()));
}
}
class CustomClazz {
String firstField;
#Override
public String toString() {
return "CustomClazz{" +
"firstField='" + firstField + '\'' +
", secondField='" + secondField + '\'' +
'}';
}
String secondField;
public String getFirstField() {
return firstField;
}
public void setFirstField(String firstField) {
this.firstField = firstField;
}
public String getSecondField() {
return secondField;
}
public void setSecondField(String secondField) {
this.secondField = secondField;
}
public CustomClazz(String firstField, String secondField) {
super();
this.firstField = firstField;
this.secondField = secondField;
}
}
Here's an article on Dozer: https://www.baeldung.com/dozer. It's a mapper that uses reflection to map same-name fields from one object to another (of a completely unrelated class).
I was wondering if this works flexibly with private fields, getters, and setters. That is,
Will private String a map to another object's private String a without either having any getters or setters?
What if only one side has a getter or setter (and the private field is named something different to make sure it's not directly accessing private fields)?
What if one has a getter and the other has a setter for totally mismatching private fields? (But the getter and setter names match.)
I wrote a test program to run in https://www.jdoodle.com/online-java-compiler:
import org.dozer.DozerBeanMapper;
public class Main {
public static class MySource {
// a -> a
private String a;
// getB() -> b
private String hidden_b;
public String getB() { return hidden_b; }
// c -> setC(c)
private String c;
// getD() -> setD(d)
private String hidden_d;
// proper getters and setters on both sides
private String proper;
public String getProper() { return proper; }
// public void setProper(String proper_) { proper = proper_; }
public MySource() {
a = "A Room with a View";
hidden_b = "The Bridge of San Luis Rey";
c = "Civilwarland in Bad Decline";
hidden_d = "Darkness at Noon";
proper = "This should copy, at minimum.";
}
public void print() {
System.out.println("Source");
System.out.println("================================");
System.out.println("a = " + a);
System.out.println("hidden_b = " + hidden_b);
System.out.println("c = " + c);
System.out.println("hidden_d = " + hidden_d);
System.out.println("--------------------------------");
System.out.println("proper = " + proper);
System.out.println("");
}
}
public static class MyTarget {
private String a;
private String b;
private String hidden_c;
private String hidden_e;
public void setC(String param) { hidden_c = param; }
public void setD(String param) { hidden_e = param; }
private String proper;
// public String getProper() { return proper; }
public void setProper(String proper_) { proper = proper_; }
public MyTarget() {}
public void print() {
System.out.println("Target");
System.out.println("================================");
System.out.println("a = " + a);
System.out.println("b = " + b);
System.out.println("hidden_c = " + hidden_c);
System.out.println("hidden_e = " + hidden_e);
System.out.println("--------------------------------");
System.out.println("proper = " + proper);
System.out.println("");
}
}
public static void main(String args[]) {
MySource s = new MySource();
s.print();
System.out.println("Now dozing...");
System.out.println("");
MyTarget t = new DozerBeanMapper().map(s, MyTarget.class);
t.print();
}
}
Note that to run the above code you must add a maven dependency:
Group ID: net.sf.dozer
Artifact ID: dozer
Version: 5.5.1
And also you must try executing a few times because of random timeouts depending on whether the dependency loads fast enough.
Anyway, my output was:
Source
================================
a = A Room with a View
hidden_b = The Bridge of San Luis Rey
c = Civilwarland in Bad Decline
hidden_d = Darkness at Noon
--------------------------------
proper = This should copy, at minimum.
Now dozing...
Target
================================
a = null
b = null
hidden_c = null
hidden_e = null
--------------------------------
proper = This should copy, at minimum.
So, it appears Dozer only works through a getter on the source and a setter on the target, which is disappointing. Or, I'm not using it correctly!
Is there a way to make Dozer more flexible? Or, another mapper library that can achieve this?
Okay, here are my findings. Hopefully this helps someone.
Dozer 5.5.1 was supposed to be able to do this via "class-level is-accessible." However, there was a bug. It was fixed for future releases, e.g. Dozer 6.1+. (The package moved to a new group, org.github.dozermapper.) The steps were a little complicated though, and eventually I gave up to try ModelMapper, which was much nicer. So here's my code.
Include this package:
Group ID: org.modelmapper
Artifact ID: modelmapper
Version: 2.3.2
Here's how to use it:
import org.modelmapper.ModelMapper;
import org.modelmapper.config.Configuration;
public class Main {
public static class MySource {
// a -> a
private String a;
// getB() -> b
private String hidden_b;
public String getB() { return hidden_b; }
// c -> setC(c)
private String c;
// getD() -> setD(d)
private String hidden_d;
// proper getters and setters on both sides
private String proper;
public String getProper() { return proper; }
// public void setProper(String proper_) { proper = proper_; }
public MySource() {
a = "A Room with a View";
hidden_b = "The Bridge of San Luis Rey";
c = "Civilwarland in Bad Decline";
hidden_d = "Darkness at Noon";
proper = "This should copy, at minimum.";
}
public void print() {
System.out.println("Source");
System.out.println("================================");
System.out.println("a = " + a);
System.out.println("hidden_b = " + hidden_b);
System.out.println("c = " + c);
System.out.println("hidden_d = " + hidden_d);
System.out.println("--------------------------------");
System.out.println("proper = " + proper);
System.out.println("");
}
}
public static class MyTarget {
private String a;
private String b;
private String hidden_c;
private String hidden_e;
public void setC(String param) { hidden_c = param; }
public void setD(String param) { hidden_e = param; }
private String proper;
// public String getProper() { return proper; }
public void setProper(String proper_) { proper = proper_; }
public MyTarget() {}
public void print() {
System.out.println("Target");
System.out.println("================================");
System.out.println("a = " + a);
System.out.println("b = " + b);
System.out.println("hidden_c = " + hidden_c);
System.out.println("hidden_e = " + hidden_e);
System.out.println("--------------------------------");
System.out.println("proper = " + proper);
System.out.println("");
}
}
public static void main(String args[]) {
ModelMapper modelMapper = new ModelMapper();
modelMapper.getConfiguration()
.setFieldMatchingEnabled(true)
.setFieldAccessLevel(Configuration.AccessLevel.PRIVATE);
MySource s = new MySource();
s.print();
System.out.println("Now dozing...");
System.out.println("");
MyTarget t = modelMapper.map(s, MyTarget.class);
t.print();
}
}
Here's my output:
Source
================================
a = A Room with a View
hidden_b = The Bridge of San Luis Rey
c = Civilwarland in Bad Decline
hidden_d = Darkness at Noon
--------------------------------
proper = This should copy, at minimum.
Now dozing...
Target
================================
a = A Room with a View
b = The Bridge of San Luis Rey
hidden_c = Civilwarland in Bad Decline
hidden_e = null
--------------------------------
proper = This should copy, at minimum.
The fourth case didn't copy over but I don't really care about that case. I think it can easily achieved with a different ModelMapper configuration though. Maybe try LOOSE copying. Or worst case, manually bind the getter and setter methods in the config.
Dozer by default uses getters and setters, however you can tell Dozer (via mapping) to access the fields directly
http://dozer.sourceforge.net/documentation/custommethods.html
BTW, Dozer 5 and 6 contains an API based mapping as well.
I want to create a hash map of objects of a class.
The class is as follows -
public class BitbucketRecordDataModel {
private String softwareId;
private String scmUrl;
private String aggregationDate;
public BitbucketRecordDataModel(String softwareId, String scmUrl, String aggregationDate) {
this.softwareId = softwareId;
this.scmUrl = scmUrl;
this.aggregationDate = aggregationDate;
}
public String getSoftwareId() {
return softwareId;
}
public void setSoftwareId(String softwareId) {
this.softwareId = softwareId;
}
public String getScmUrl() {
return scmUrl;
}
public void setScmUrl(String scmUrl) {
this.scmUrl = scmUrl;
}
public String getAggregationDate() {
return aggregationDate;
}
public void setAggregationDate(String aggregationDate) {
this.aggregationDate = aggregationDate;
}
}
I am creating a Hash map having key as String and trying to insert values into the hash map. But when I try to retrieve the details of the hash map, I get null and some very weird values which is the name of my class.
HashMap<String, BitbucketRecordDataModel> map = new HashMap<String, BitbucketRecordDataModel>();
cacheCondition = "hi";
username = "hi1";
protocol = "hi2";
BitbucketRecordDataModel bitbucketRecordDataModel = new BitbucketRecordDataModel(cacheCondition, username, protocol);
map.put(repoName, bitbucketRecordDataModel);
System.out.println(map.get("deployment-service-api.git"));
I am very new to Java and Hash Maps. What am I doing wrong and why I am getting such weird values?
First of all, you should override toString() method of Class. If you don't override it and call from any object instance, it responses as implementation of Object class. You can find the basic implementation of it here please find toString() Method
Please copy shared code block for toString() method below and paste it in the class.
Also i noticed that you define repoName as key while putting data to map but you use deployment-service-api.git as a key while retrieving the data.
Please be sure use the same key value.
#Override
public String toString() {
return "BitbucketRecordDataModel{" +
"softwareId='" + softwareId + '\'' +
", scmUrl='" + scmUrl + '\'' +
", aggregationDate='" + aggregationDate + '\'' +
'}';
}
Ok so I'm trying to get a better understanding of how to return a private variable from a class that I have created. I've only provided a small snippet of my main program to explain my question, so if more information is needed please let me know. My goal is to return a string from the class (working great), but also be able to return the private variables individually as needed (example used below is "flight_number").
public class Flights {
private String dest_city, dest_state, departureDate, departureTime;
private int flight_number;
public Flights(String city, String state, String dDate, String dTime, int flightNumber) {
dest_city = city;
dest_state = state;
departureDate = dDate;
departureTime = dTime;
flight_number = flightNumber;
}
public String toString() {
return "Flight number: " + flight_number + " Destination: " + dest_city + "," + dest_state + " Departing on:" + departureDate + " at" + departureTime + ".";
}
}
public class dummy {
public static void main(String[] args) {
// Uses the constructor to set values
Flights flight1 = new Flights("Houston", "Texas", "12/20/2014", "12:40 pm", 100);
System.out.println(flight1);
System.out.println(flight_number); // Error: `flight_number` cannot be resolved to a variable.
}
}
You need to add a public getter in Flights and call it from main:
public class Flights {
// all the private fields
public int getFlightNumber() {
return this.flight_number;
}
}
In Main:
public static void main(String[] args) {
Flights flight1 = new Flights("Houston", "Texas"); //...
System.out.println(flight1);
System.out.println(flight1.getFlightNumber()); // call the getter
}
You should start with an editor like eclipse and that should help you get started quickly. Getters and Setters is what you need, but start with Eclipse and you should do better.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class clsWarehouse {
private static int iChoice;
private int iItemID;
private String strItemName;
private String strItemDescription;
private int iItemPrice;
private String strSize;
private String strSex;
public clsWarehouse (int id, String name, String description, int price, String size, String sex){
iItemID = id;
strItemName = name;
strItemDescription = description;
iItemPrice = price;
strSize = size;
strSex = sex;
}
public ArrayList <clsWarehouse> AllItems;
public clsWarehouse(){
AllItems = new ArrayList <clsWarehouse>();
AllItems.add(new clsWarehouse(3, "T-Shirt", "Male T-Shirt", 30, "15", "Male"));
System.out.println(AllItems);
}
public static void main(String[] args){
clsWarehouse c = new clsWarehouse();
}
}
}
Hello,
I want to get the values stored in the ArrayList AllItems but all i get is the memory location [clsWarehouse#a83b8a]. Can someone help me with this.
Thanks!
You need to override the toString() in your clsWarehouse class. The System.out.println internally calls the toString() of the object in the list. Since you do not have the toString() method overridden in your class, you get the below as your output.
getClass().getName() + '#' + Integer.toHexString(hashCode())
The above is the toString() implementation of the Object class.
Update:-
In your clsWarehouse class, add the below method.
public String toString(){
return "clsWarehouse"; //Modify this to return whatever you want to display in your sysout.
}
You need to iterate through the array list to get the values . Also need to convert this guy to string format using toString(). Then,
for (int i=0;i<AllItems .length();i++){
//Then get the values one by one
}
Hope this helps you .
Add this method in clsWarehouse class
public String toString(){
return "iItemID: " + iItemID +" strItemName: "+ strItemName + " strItemDescription: "+ strItemDescription +" iItemPrice "+ iItemPrice: + " strSize: " + strSize + " strSex: "+strSex;
}
Change this
System.out.println(AllItems);
to
for(clsWarehouse item : AllItems){
System.out.println(item.toString());
}