I have a function that sets the value if and only the value given is contained in with the enum declared. I'm then trying to get the value via get Method but I'm getting the default value. The setter method is not getting the new value and updating it.
public enum BranchLocations {ONE,TWO,THREE,FOUR,FIVE};
private String BranchName ="Branch Name";
public boolean setBranchLocation(String branchLocation) {
for (BranchLocations b : BranchLocations.values()) {
if (b.name().equals(branchLocation)) {
this.BranchName = branchLocation;
return true;
}
}
return false;
}
public String getBranchLocation() {
return this.BranchName ;
}
I'm learning enum currently and not very familiar with it. I'm just checking if the value is contained in the enum by a for loop and .equals method
clarification - tester im running it against
public class Main {
public static void main(String[] args){
Bank bank = new Bank("LhblVEWZXmtjn3gMykBaqfN& &h", Bank.BranchLocations.values()[0]);
System.out.println(Bank.BranchLocations.values()[0]);
System.out.println(Bank.BranchLocations.values()[1].toString());
String newBranchLocation = Bank.BranchLocations.values()[1].toString();
System.out.println(bank.getBranchLocation());
bank.setBranchLocation(newBranchLocation);
System.out.println(bank.getBranchLocation());
System.out.println(
(bank.setBranchLocation(newBranchLocation) && bank.getBranchLocation().equals(newBranchLocation)));
}
}
public enum BranchLocations {
ONE("ONE"),
TWO("TWO"),
THREE("THREE"),
FOUR("FOUR"),
FIVE("FIVE");
private String BranchName = new String();
BranchLocations(String val){BranchName = val;}
public String getBranchLocation() {return BranchName;}
public boolean setBranchLocation(String branchLocation) {
for (BranchLocations b : BranchLocations.values()) {
if (b.name().equals(branchLocation)) {
this.BranchName = branchLocation;
return true;
}
}
return false;
}
}
In the enum, you have just declared the names, not the values. But, in your method, you are retrieving the values for the test. This is not the intended behaviour.
Do:
if (b.toString().equals(branchLocation)) {
this.BranchName = branchLocation;
return true;
}
or define a value for each one of the names in the Enum:
public enum BranchLocations {
ONE("ONE"),
TWO("TWO"),
THREE("THREE"),
FOUR("FOUR"),
FIVE("FIVE")
};
I am having a hard time finding out how to write my toString Method to get the output of each of my bears in my program. I want the output to show "Race - Points - TotalPoints". But can't manage to get it right even though the rest of the code seems to compile.
Do i need to have the toString defined in both classes or what am I missing? I have checked a couple of other questions that are resembling and that seems to be an alternativ? But how is it most effectively implemented?
First off the bear class:
import java.util.ArrayList;
public class Bear {
public static void main(String[] args) {
Bear b = new Bear("Sebastian", 100, "Brownbear");
ArrayList <Bear> bears = new ArrayList<Bear>();
bears.add(b);
}
private String name;
private int points;
private String race;
public Bear(String name, int points, String race) {
this.name = name;
this.points = points;
this.race = race;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getRace() {
return race;
}
public void setRace(String race) {
this.race = race;
}
public int getInitialPoints() {
return points;
}
public int getPoints() {
int oldPoints = points;
points /= 2;
return oldPoints;
}
}
Secondly the BearCollection class:
import java.util.ArrayList;
public class BearCollection {
ArrayList <Bear> bears = new ArrayList<Bear>();
int totalPoints = 0;
public void add (Bear b) {
for (Bear inCollection : bears) {
if(b.getName().equals(inCollection.getName())) {
return;
}
}
for (Bear inCollection : bears)
if (b.getRace().equals(inCollection.getRace())) {
for(int i = bears.size(); i > 0; i --) {
if(bears.get(i).getRace().equals(b.getRace())) {
b.getPoints();
i = 0;
}
}
}
totalPoints += b.getInitialPoints();
bears.add(b) ;
}
public String toString(){
return ;
}
As you were told, just override the toString method. For performance use StringBuilder, rather than String concatenation.
import java.util.*;
public class ans{
public static void main(String[] args){
Bears bears = new Bears();
bears.add(new Bear());
bears.add(new Bear());
bears.add(new Bear());
System.out.println(bears);
}
}
class Bear{
public String toString(){
return "I am a bear";
}
}
class Bears{
private ArrayList<Bear> bears = new ArrayList<Bear>();
public void add(Bear bear){
bears.add(bear);
}
public String toString(){
StringBuilder str = new StringBuilder();
if(!bears.isEmpty()){ // If there is no bears, return empty string
str.append(bears.get(0)); // Append the first one
for(int index = 1; index < bears.size(); index++){ // For all others
str.append(" - "); // Append a separator and the bear string
str.append(bears.get(index));
}
}
return str.toString();
}
}
Edit To print A-B-C-D, just associate every item with a separator except one. A(-B)(-C)(-D) or (A-)(B-)(C-)D. You could add easily a beginning and a end mark.
overriding the toString in Bear class would resolve the issue.
If you need to print out the entire collection of Bears, you'd need to give Bear a toString, something like:
return "Bear("+name+","+points+","+race+")";
Then, in the toString of BearCollection, just write a for each loop in the toString to go through and call toString on each bear in the collection, printing them out.
Writing the title was a bit tricky for this question :p
This is a basic java query!
I am using google cloud and it has different methods, such as launchInstance, listInstances and terminateInstance and so on.. Here, launchInstance will return a type String as Success or Fail, listInstances will return ArrayList, and so forth.
Now, I want a generic return type, so I made a class which has data entries such as status, reason, and dataRequired which will eventually send the data that is required, i.e String or ArrayList or HashMap.
How can I achieve this functionality.
Here is sample code that I was thinking of doing:
public class ResponseHelper {
private String status;
private String reason;
private String type;
private Object data;
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getReason() {
return reason;
}
public void setReason(String reason) {
this.reason = reason;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public void dataRequired(Object data) {
switch(getType()) {
case "ArrayList": this.data=(ArrayList<String>)data;
}
}
}
If you need a Generic return type of any object in Java, just return Object as the type.(Instead of creating a separate new class for it) Then you can check which object it is and do your stuff. Below is a simple program that you can get an idea out of it
public class GenericReturn {
public static void main(String[] args) {
Object output = returnMeSomething(2);
System.out.println(output.getClass().getSimpleName());
output = returnMeSomething(1);
System.out.println(output.getClass().getSimpleName());
output = returnMeSomething(0);
System.out.println(output.getClass().getSimpleName());
}
/** This can return any Object you want as it has Object as return type*/
public static Object returnMeSomething(int num) {
if (num == 1) {
return "Test";
}
else if (num == 2) {
return new HashMap();
}
return new ArrayList();
}
}
This output as below
HashMap
String
ArrayList
I have a simple loop that checks for any duplicate results,
where studresults holds my results , result is the object result given to the method and r is the current object from the array.
I have been using this method successfully throughout the program although it is not working in this case even though when I debug result and r , are exactly the same does anyone know why this might be? I have tried #Override already as suggested in other answers to no avail.
I am trying to stop duplicated array elements by throwing an exception.
for(Result r : studresults)
{
if(r.equals(result))
{
return false;
}
}
EDIT OK HERE IS THE WHOLE CLASS>
package ams.model;
import java.util.ArrayList;
import java.util.Arrays;
import ams.model.exception.EnrollmentException;
public abstract class AbstractStudent implements Student {
private int studentId;
private String studentName;
private ArrayList<Course> studcourses = new ArrayList<Course>();
private ArrayList<Result> studresults = new ArrayList<Result>();
public AbstractStudent(int studentId, String studentName) {
this.studentId = studentId;
this.studentName = studentName;
}
public String getFullName() {
return studentName;
}
public int getStudentId() {
return studentId;
}
public Result[] getResults() {
Result[] res = studresults.toArray(new Result[0]);
if(res.length > 0 )
{
return res;
}
return null;
}
public boolean addResult(Result result)
{
for(Result r : studresults)
{
if(r.equals(result))
{
return false;
}
}
studresults.add(result);
return true;
}
public void enrollIntoCourse(Course c)
{
//for re-enrollment
if(studcourses.contains(c))
{
studcourses.remove(c);
studresults.clear();
}
studcourses.add(c);
}
public void withdrawFromCourse(Course c) throws EnrollmentException
{
if(studcourses.size() > 0)
{
studcourses.remove(c);
}
else
throw new EnrollmentException();
}
public Course[] getCurrentEnrolment()
{
return studcourses.toArray(new Course[0]);
}
public abstract int calculateCurrentLoad();
public int calculateCareerPoints() {
// TODO Auto-generated method stub
return 0;
}
public String toString()
{
return studentId + ":" + studentName +":" + calculateCurrentLoad();
}
}
Do you already override hashCode method in Result?
If you override equals, you have to override the hashCode method also to allow you return the same hashcode for the similar objects (objects which has the same value but actually different object instances).
I think the default implementation of hashcode will returns different value for a different object instances even though they have the same values.
Instead I converted toString and then compared and it works???
Makes me think there was something slightly unidentical before?
New method
public boolean addResult(Result r)
{
for (Result s : studresults)
{
String sr1 = s.toString();
String sr2 = r.toString();
if(sr1.equals(sr2))
{
return false;
}
}
What is the best way to use the values stored in an Enum as String literals?
For example:
public enum Modes {
some-really-long-string,
mode1,
mode2,
mode3
}
Then later I could use Mode.mode1 to return its string representation as mode1. Without having to keep calling Mode.mode1.toString().
You can't. I think you have FOUR options here. All four offer a solution but with a slightly different approach...
Option One: use the built-in name() on an enum. This is perfectly fine if you don't need any special naming format.
String name = Modes.mode1.name(); // Returns the name of this enum constant, exactly as declared in its enum declaration.
Option Two: add overriding properties to your enums if you want more control
public enum Modes {
mode1 ("Fancy Mode 1"),
mode2 ("Fancy Mode 2"),
mode3 ("Fancy Mode 3");
private final String name;
private Modes(String s) {
name = s;
}
public boolean equalsName(String otherName) {
// (otherName == null) check is not needed because name.equals(null) returns false
return name.equals(otherName);
}
public String toString() {
return this.name;
}
}
Option Three: use static finals instead of enums:
public final class Modes {
public static final String MODE_1 = "Fancy Mode 1";
public static final String MODE_2 = "Fancy Mode 2";
public static final String MODE_3 = "Fancy Mode 3";
private Modes() { }
}
Option Four: interfaces have every field public, static and final:
public interface Modes {
String MODE_1 = "Fancy Mode 1";
String MODE_2 = "Fancy Mode 2";
String MODE_3 = "Fancy Mode 3";
}
Every enum has both a name() and a valueOf(String) method. The former returns the string name of the enum, and the latter gives the enum value whose name is the string. Is this like what you're looking for?
String name = Modes.mode1.name();
Modes mode = Modes.valueOf(name);
There's also a static valueOf(Class, String) on Enum itself, so you could also use:
Modes mode = Enum.valueOf(Modes.class, name);
You could override the toString() method for each enum value.
Example:
public enum Country {
DE {
#Override
public String toString() {
return "Germany";
}
},
IT {
#Override
public String toString() {
return "Italy";
}
},
US {
#Override
public String toString() {
return "United States";
}
}
}
Usage:
public static void main(String[] args) {
System.out.println(Country.DE); // Germany
System.out.println(Country.IT); // Italy
System.out.println(Country.US); // United States
}
As Benny Neugebauer mentions, you could overwrite the toString(). However instead overwriting the toString for each enum field I like more something like this:
public enum Country{
SPAIN("España"),
ITALY("Italia"),
PORTUGAL("Portugal");
private String value;
Country(final String value) {
this.value = value;
}
public String getValue() {
return value;
}
#Override
public String toString() {
return this.getValue();
}
}
You could also add a static method to retrieve all the fields, to print them all, etc.
Simply call getValue to obtain the string associated to each Enum item
mode1.name() or String.valueOf(mode1). It doesn't get better than that, I'm afraid
public enum Modes {
MODE1("Mode1"),
MODE2("Mode2"),
MODE3("Mode3");
private String value;
public String getValue() {
return value;
}
private Modes(String value) {
this.value = value;
}
}
you can make a call like below wherever you want to get the value as a string from the enum.
Modes.MODE1.getvalue();
This will return "Mode1" as a String.
For my enums I don't really like to think of them being allocated with 1 String each. This is how I implement a toString() method on enums.
enum Animal
{
DOG, CAT, BIRD;
public String toString(){
switch (this) {
case DOG: return "Dog";
case CAT: return "Cat";
case BIRD: return "Bird";
}
return null;
}
}
You can use Mode.mode1.name() however you often don't need to do this.
Mode mode =
System.out.println("The mode is "+mode);
As far as I know, the only way to get the name would be
Mode.mode1.name();
If you really need it this way, however, you could do:
public enum Modes {
mode1 ("Mode1"),
mode2 ("Mode2"),
mode3 ("Mode3");
private String name;
private Modes(String s) {
name = s;
}
}
my solution for your problem!
import java.util.HashMap;
import java.util.Map;
public enum MapEnumSample {
Mustang("One of the fastest cars in the world!"),
Mercedes("One of the most beautiful cars in the world!"),
Ferrari("Ferrari or Mercedes, which one is the best?");
private final String description;
private static Map<String, String> enumMap;
private MapEnumSample(String description) {
this.description = description;
}
public String getEnumValue() {
return description;
}
public static String getEnumKey(String name) {
if (enumMap == null) {
initializeMap();
}
return enumMap.get(name);
}
private static Map<String, String> initializeMap() {
enumMap = new HashMap<String, String>();
for (MapEnumSample access : MapEnumSample.values()) {
enumMap.put(access.getEnumValue(), access.toString());
}
return enumMap;
}
public static void main(String[] args) {
// getting value from Description
System.out.println(MapEnumSample.getEnumKey("One of the fastest cars in the world!"));
// getting value from Constant
System.out.println(MapEnumSample.Mustang.getEnumValue());
System.out.println(MapEnumSample.getEnumKey("One of the most beautiful cars in the world!"));
System.out.println(MapEnumSample.Mercedes.getEnumValue());
// doesnt exist in Enum
System.out.println("Mustang or Mercedes, which one is the best?");
System.out.println(MapEnumSample.getEnumKey("Mustang or Mercedes, which one is the best?") == null ? "I don't know!" : "I believe that "
+ MapEnumSample.getEnumKey("Ferrari or Mustang, which one is the best?") + " is the best!.");
// exists in Enum
System.out.println("Ferrari or Mercedes, wich one is the best?");
System.out.println(MapEnumSample.getEnumKey("Ferrari or Mercedes, which one is the best?") == null ? "I don't know!" : "I believe that "
+ MapEnumSample.getEnumKey("Ferrari or Mercedes, which one is the best?") + " is the best!");
}
}
You can simply use:
""+ Modes.mode1
public enum Environment
{
PROD("https://prod.domain.com:1088/"),
SIT("https://sit.domain.com:2019/"),
CIT("https://cit.domain.com:8080/"),
DEV("https://dev.domain.com:21323/");
private String url;
Environment(String envUrl) {
this.url = envUrl;
}
public String getUrl() {
return url;
}
}
String prodUrl = Environment.PROD.getUrl();
It will print:
https://prod.domain.com:1088/
This design for enum string constants works in most of the cases.
Enum is just a little bit special class. Enums can store additional fields, implement methods etc. For example
public enum Modes {
mode1('a'),
mode2('b'),
mode3('c'),
;
char c;
private Modes(char c) {
this.c = c;
}
public char character() {
return c;
}
}
Now you can say:
System.out.println(Modes.mode1.character())
and see output:
a
package com.common.test;
public enum Days {
monday(1,"Monday"),tuesday(2,"Tuesday"),wednesday(3,"Wednesday"),
thrusday(4,"Thrusday"),friday(5,"Friday"),saturday(6,"Saturday"),sunday(7,"Sunday");
private int id;
private String desc;
Days(int id,String desc){
this.id=id;
this.desc=desc;
}
public static String getDay(int id){
for (Days day : Days.values()) {
if (day.getId() == id) {
return day.getDesc();
}
}
return null;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
};
This method should work with any enum:
public enum MyEnum {
VALUE1,
VALUE2,
VALUE3;
public int getValue() {
return this.ordinal();
}
public static DataType forValue(int value) {
return values()[value];
}
public String toString() {
return forValue(getValue()).name();
}
}
i found this one is more easy for preventing type error:
public enum Modes {
some-really-long-string,
mode1,
mode2,
mode3;
String str;
Modes(){
this.str = super.name();
}
#Override
#NonNull
public String toString() {
return str;
}
however - this may work when you need to use a String on a log/println or whenever java compiles the toString() method automatically, but on a code line like this ->
// sample method that require (string,value)
intent.putExtra(Modes.mode1 ,shareElement.getMode()); // java error
// first argument enum does not return value
instead as mentioned above you will still have to extend the enum and use .name() in those cases like this:
intent.putExtra(Modes.mode1.name() ,shareElement.getMode());
after many tries I have come with this solution
public static enum Operation {
Addition, Subtraction, Multiplication, Division,;
public String getUserFriendlyString() {
if (this==Addition) {
return " + ";
} else if (this==Subtraction) {
return " - ";
} else if (this==Multiplication) {
return " * ";
} else if (this==Division) {
return " / ";
}
return "undefined";
}
}
You can try this:
public enum Modes {
some-really-long-string,
mode1,
mode2,
mode3;
public String toString(){
switch(this) {
case some-really-long-string:
return "some-really-long-string";
case mode2:
return "mode2";
default: return "undefined";
}
}
}
use mode1.name() or String.valueOf(Modes.mode1)