10 Tips To Override Tostring() Method Inwards Coffee - Tostringbuilder Netbeans Eclipse

Java toString method

toString method inward Java is used to render clear in addition to concise information most Object inward human readable format. Influenza A virus subtype H5N1 correctly overridden toString method tin post away assistance inward logging in addition to debugging of Java program past times providing valuable in addition to meaningful information. Since toString() is defined inward java.lang.Object degree in addition to its default implementation don't render much information, it's ever a best practise to override the toString method inward sub class. In fact, if you lot are creating value degree or domain degree e.g. Order, Trade or Employee,  always override equals,hashCode, compareTo in addition to toString method inward Java.  By default toString implementation produces output inward the shape package.class@hashCode e.g. for our toString() example, Country class’ toString() method volition impress test.Country@18e2b22 where 18e2b22 is hashCode of an object inward hex format, if you lot telephone shout out upward hashCode method it volition render 26094370, which is decimal equivalent of 18e2b22. This information is non really useful piece troubleshooting whatsoever problem. 

Let’s come across a existent life illustration where you lot are troubleshooting network connectivity issues, inward instance of this you lot desire to know which host in addition to port your organisation is trying to connect in addition to if Socket or ServerSocket degree solely impress default toString information than its impossible to figure out the actual problem, but alongside a decent toString implementation they tin post away impress useful information similar hostname in addition to port. 

In this Java  tutorial nosotros volition come across to a greater extent than or less tips to override toString method alongside code examples.

How to override toString method inward Java:

overriding whatsoever method inward Java, you lot involve to follow rules of method overriding. Any means at that topographic point are many means to implement or override toString() method e.g.  You tin post away write this method manually, you lot tin post away work IDE similar Netbeans in addition to Eclipse to generate toString method or you lot tin post away work Apache common ToStringBuilder to generate toString method inward multiple styles similar unmarried line, multi-line etc. Here are few points to call upward piece overriding toString() method inward Java, which volition assistance you lot to acquire most from your toString() implementation.

Print formatted appointment e.g. dd-MM-yy instead of raw date

This is really helpful tip piece overriding Java’s toString() method. Since toString() of java.util.Date degree does non impress formatted appointment in addition to includes lots of details which is non ever necessary. If you lot are using a particular DateFormat e.g. dd-MM-yy inward your application, they you lot definitely desire to come across dates on that format instead of default. IDE commonly does non generate formatted Date output in addition to this is something you lot involve to do past times yourself  but its worth of effort. See How to impress Date inward ddMMyy format inward Java for to a greater extent than details on formatting Date inward Java. You tin post away either work SimpleDateFormat degree or Joda Date fourth dimension library for this purpose.

Document toString format

If your toString() method is non printing information inward price of field=value, Its practiced stance to document format of toString, specially for value objects similar Employee or Student. For illustration if toString() method of Employee prints "John-101-Sales-9846387321" than its practiced stance to specify format every bit "name-id-department-contact", but at the same fourth dimension don't permit your client extract information from toString() method in addition to you lot should ever render corresponding getter methods similar getName(), getId(), getContact() etc, because extracting information from toString() representation of Object is delicate in addition to mistake prone in addition to client should ever a cleaner means to asking information.

Use StringBuilder to generate toString output

If you lot writing code for toString() method inward Java, in addition to thus work StringBuilder to append private attribute.  If you lot are using IDE similar Eclipse, Netbeans or IntelliJ in addition to thus too using  StringBuilder in addition to append() method instead of + operator to generate toString method is practiced way. By default both Eclipse in addition to Netbeans generate toString method alongside concatenation operator .

Use @Override annotation

Using @Override notation piece overriding method inward Java is i of the best practise inward Java. But this tip is non every bit of import every bit it was inward instance of overriding equals() in addition to compareTo() method, every bit overloading instead of overriding tin post away do to a greater extent than subtle bugs there. Anyway it’s best to using @Override annotation.

Print contents of Array instead of printing array object

Array is an object inward Java but it doesn’t override toString method in addition to when you lot impress array, it volition work default format which is non really helpful because nosotros want  to come across contents of Array. By the means this is to a greater extent than or less other argue why char[] array are preferred over String for storing sensitive information e.g. password. Take a minute to come across if printing content of array helps your user or non in addition to if it brand feel than impress contents instead of array object itself. Apart from surgical procedure argue prefer Collection similar ArrayList or HashSet over Array for storing other objects.

Bonus Tips

Here are few to a greater extent than bonus tips on overriding toString method inward Java

1. Print output of toString inward multiple job or unmarried job based upon it length.

2. Include amount qualified refer of degree inward toString representation e.g. package.class to avoid whatsoever confusion/

3. You tin post away either skip zilch values or demonstrate them, its amend to exit them. Sometime they are useful every bit they dot which fields are zilch at the fourth dimension of whatsoever incident e.g. NullPointerException.

4. Use cardinal value format similar member.name=member.value every bit most of IDE too follows that.

5. Include inherited members if you lot affair they render must bring information inward fry class.

6. Sometime an object contains many optional in addition to mandatory parameters similar nosotros shown inward our Builder blueprint example, when its non practically possible to impress all fields inward those cases printing a meaningful information, non necessary fields is better.

 toString Example inward Java 

We volition work next degree to demonstrate our toString examples for Netbeans, Eclipse in addition to Apache's ToStringBuilder utility.

/**
 * Java program to demonstrate How to override toString() method inward Java.
 * This Java programme shows How tin post away you lot work IDE similar Netbeans or Eclipse
 * in addition to Open beginning library similar Apache common ToStringBuilder to

 * override toString inward Java.
 *
 * @author .blogspot.com
 */

public class Country{
    private String name;
    private String capital;
    private long population;
    private Date independenceDay;

    public Country(String name){
        this.name = name;
    }
 
    public String getName(){ return name; }
    public void setName(String name) {this.name = name;}
 
    public String getCapital() {return capital;}
    public void setCapital(String capital) {this.capital = capital;}

    public Date getIndependenceDay() {return independenceDay;}
    public void setIndependenceDay(Date independenceDay) {this.independenceDay = independenceDay;}

    public long getPopulation() { return population; }
    public void setPopulation(long population) {this.population = population; }

    @Override
    public String toString() {
        return "Country{" + "capital=" + uppercase + ",
               population=" + population + ",
               independenceDay=" + independenceDay + '}';

    }

    public void setIndependenceDay(String date) {
        DateFormat format = new SimpleDateFormat("dd/MM/yyyy");
        try {
            this.independenceDay = format.parse(date);
        } catch (ParseException ex) {
            Logger.getLogger(Country.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
   

   public static void main(String args[]){
            Country Republic of Republic of India = new Country("India");
            India.setCapital("New Delhi");
            India.setIndependenceDay("15/07/1947");
            India.setPopulation(1200000000);
           
            System.out.println(India);      
   }

}

toString method created past times Netbeans IDE
toString method generated past times Netbeans IDE arrive at next output for inward a higher house degree :

Country{capital=New Delhi, population=1200000000, independenceDay=Fri Aug fifteen 00:00:00 VET 1947}

If you lot await at inward a higher house output you lot notice that NetBeans does non generated formatted Date for you, instead it calls toString() method of java.util.Date class.

toString() code generated past times Eclipse IDE:

By default Eclipse generates next toString method :

@Override
    public String toString() {
        return "Country [name=" + refer + ", capital=" + capital
                + ", population=" + population + ", independenceDay="
                + independenceDay + "]";
    }

You tin post away generate code for toString method inward Eclipse past times clicking Source --Generate toString(). It too render several options similar choosing code mode e.g. concatenation operator or StringBuffer etc. Here is the output of toString() method nosotros merely created past times Eclipse :

Country [name=India, capital=New Delhi, population=1200000000, independenceDay=Tue Jul 15 00:00:00 VET 1947]

Using ToStringBuilder for overriding Java toString method

Along alongside many useful classes similar PropertyUtils, EqualsBuilder or HashCodeBuilder; Apache common provides to a greater extent than or less other jewel called ToStringBuilder which tin post away generate code for toString() method inward dissimilar styles. Let’s how does output of toString method looks similar inward elementary mode in addition to multi-line style.

Simple Style:
India,New Delhi,1200000000,Fri Aug 15 00:00:00 VET 1947

Multi-line style:
test.Country@f0eed6[
  name=India
  capital=New Delhi
  population=1200000000
  independenceDay=Fri Aug 15 00:00:00 VET 1947
]

NO_FIELD_NAMES_STYLE
test.Country@1d05c81[India,New Delhi,1200000000,Fri Aug 15 00:00:00 VET 1947]

SHORT_PREFIX_STYLE
Country[name=India,capital=New Delhi,population=1200000000,independenceDay=Fri Aug 15 00:00:00 VET 1947]

ToStringStyle.DEFAULT_STYLE
test.Country@1d05c81[name=India,capital=New Delhi,population=1200000000,independenceDay=Fri Aug 15 00:00:00 VET 1947]

Similarly Google’s opened upward beginning library Guava too render convenient API to generate code for toString method inward Java.

When toString method is invoked inward Java

toString is a rather special method in addition to invoked past times many Java API methods similar println(), printf(), loggers, assert statement, debuggers inward IDE, piece printing collections in addition to alongside concatenation operator. If subclass doesn't override toString() method than default implementation defined inward Object degree gets invoked. Many programmers either work logging API similar Log4J or java.util.Logger to impress logs in addition to frequently move past times Object there.  logger.info("Customer non constitute : " + customer) in addition to if Customer doesn't override toString in addition to impress meaningful information similar customerId, customerName etc than it would hold upward hard to diagnose the problem. This why its ever practiced to override toString inward Java.let's come across to a greater extent than or less benefits of doing this.

Benefits of overriding toString method:

1) As discussed above, correctly overridden toString helps inward debugging past times printing meaningful information.

2) If value objects are stored inward Collection than printing collection volition invoke toString on stored object which tin post away impress really useful information.One of the classic illustration of non overriding toString method is Array inward Java, which prints default implementation rather than contents of array. Though at that topographic point are pair of ways to impress contents of array using Arrays.toString() etc but given Array is an object inward Java, would bring been much amend if Array know how to impress itself much similar Collection classes similar List or Set.

3) If you lot are debugging Java programme inward Eclipse than using picket or inspect characteristic to await object, toString volition definitely assistance you.

These are merely to a greater extent than or less of the benefits you lot acquire past times implementing or overriding toString method inward Java, at that topographic point are many to a greater extent than which you lot acquire in addition to larn past times yourself. I promise these tips volition assistance you lot to acquire most of your toString implementation. Let us know  if you lot whatsoever unique toString() tips which has helped you lot inward your Java application.

Further Learning
Complete Java Masterclass
4 ways to compare String inward Java

Why String is immutable inward Java

Why String is a pop HashMap cardinal inward Java

How SubString plant inward Java

How to separate String inward Java

How to supervene upon String using regular aspect inward Java

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