What is the difference between field variable attribute and property in Java POJOs

Question

When referring to internal private variables of Java POJOs that have getters setters  I ve used the following terms    field variable attribute property   Is there any difference between the above  If so  what is the correct term to use  Is there a different term to use when this entity is persisted

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The difference between a variable  field  attribute  and property in Java  A variable is the name given to a memory location  It is the basic unit of storage in a program  A field is a data member of a class  Unless specified otherwise  a field can be public  static  not static and final  An attribute is another term for a field  It   s typically a public field that can be accessed directly   In NetBeans or Eclipse  when we type object of a class and after that dot    they give some suggestion which are called Attributes   A property is a term used for fields  but it typically has getter and setter combination

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My understanding is as below  and I am not saying that this is 100  correct  I might as well be mistaken    A variable is something that you declare  which can by default change and have different values  but that can also be explicitly said to be final  In Java that would be   public class Variables        List lt Object gt  listVariable     declared but not assigned     final int aFinalVariableExample   5     declared  assigned and said to be final       Integer foo List lt Object gt  someOtherObjectListVariable               declare           Object iAmAlsoAVariable              assign a value           iAmAlsoAVariable   5              change its value           iAmAlsoAVariable   8           someOtherObjectListVariable add iAmAlsoAVariable            return new Integer              So basically  a variable is anything that is declared and can hold values  Method foo above returns a variable for example   It returns a variable of type Integer which holds the memory address of the new Integer    Everything else you see above are also variables  listVariable  aFinalVariableExample and explained here   A field is a variable where scope is more clear  or concrete   The variable returning from method foo  s scope is not clear in the example above  so I would not call it a field  On the other hand  iAmAlsoVariable is a  local  field  limited by the scope of the method foo  and listVariable is an  instance  field where the scope of the field  variable  is limited by the objects scope   A property is a field that can be accessed   mutated  Any field that exposes a getter   setter is a property   I do not know about attribute and I would also like to repeat that this is my understanding of what variables  fields and properties are

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Dietel and Dietel have a nice way of explaining fields vs variables      Together a class   s static variables and instance variables are known as its fields      Section 6 3      Variables should be declared as fields only if they   re required for use in more than one method of the class or if the program should save their values between calls to the class   s methods      Section 6 4   So a class s fields are its static or instance variables - i e  declared with class scope   Reference  - Dietel P   Dietel  H  - Java    How To Program  Early Objects   Tenth Edition  2014

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If you take clue from Hibernate   Hibernate reads writes Object s state with its field   Hibernate also maps the Java Bean style properties to DB Schema  Hibernate Access the fields for loading saving the object  If the mapping is done by property  hibernate uses the getter and setter   It is the Encapsulation that differentiates means where you have getter setters for a field and it is called property  withthat and we hide the underlying data structure of that property within setMethod  we can prevent unwanted change inside setters  All what encapsulation stands for     Fields must be declared and initialized before they are used  Mostly for class internal use   Properties can be changed by setter and they are exposed by getters  Here field price has getter setters so it is property   class Car   private double price   public double getPrice           private void setPrice double newPrice             lt class name  Car      gt   lt property name  price  column  PRICE   gt   lt  class gt    Similarly using fields   In hibernate it is the recommended way to MAP using fields  where private int id  is annotated  Id  but with Property you have more control   class Car    private double price     lt class name  Car  gt   lt property name   price  column  PRICE  access  field   gt   lt  class gt    Java doc says  Field is a data member of a class  A field is non static  non-transient instance variable  Field is generally a private variable on an instance class

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variable - named storage address  Every variable has a type which defines a memory size  attributes and behaviours  There are for types of Java variables  class variable  instance variable  local variable  method parameter    pattern  lt Java type gt   lt name gt       for example int myInt  String myString  CustomClass myCustomClass    field - member variable or data member  It is a variable inside a class class variable or instance variable   attribute - in some articles you can find that attribute it is an object representation of class variable  Object operates by attributes which define a set of characteristics    CustomClass myCustomClass   new CustomClass    myCustomClass myAttribute    quot poor fantasy quot      myAttribute  is an attribute of  myCustomClass  object with a  quot poor fantasy quot  value   property - field   bounded getter setter  It has a field syntax but uses methods under the hood  Java does not support it in pure form  Take a look at Objective-C  Swift  Kotlin  For example Kotlin sample    field - Backing Field class Person       var name  String    quot default name quot          get     field         set value    field   value        using val person   Person   person name    quot Alex quot        setter is used println person name        getter is used   Swift variable  property

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Yes  there is   Variable can be local  field  or constant  although this is technically wrong   It s vague like attribute  Also  you should know that some people like to call final non-static  local or instance  variables   Values   This probably comes from emerging JVM FP languages like Scala   Field is generally a private variable on an instance class  It does not mean there is a getter and a setter   Attribute is a vague term  It can easily be confused with XML or Java Naming API  Try to avoid using that term   Property is the getter and setter combination   Some examples below  public class Variables          Constant     public final static String MY VARIABLE    that was a lot for a constant          Value     final String dontChangeMeBro    my god that is still long for a val          Field     protected String flipMe    wee             Property     private String ifYouThoughtTheConstantWasVerboseHaHa         Still the property     public String getIfYouThoughtTheConstantWasVerboseHaHa             return ifYouThoughtTheConstantWasVerboseHaHa               And now the setter     public void setIfYouThoughtTheConstantWasVerboseHaHa String ifYouThoughtTheConstantWasVerboseHaHa            this ifYouThoughtTheConstantWasVerboseHaHa   ifYouThoughtTheConstantWasVerboseHaHa             There are many more combinations  but my fingers are getting tired

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From here  http   docs oracle com javase tutorial information glossary html     field   A data member of a class  Unless specified otherwise  a field is not static        property   Characteristics of an object that users can set  such as the color of a window         attribute   Not listed in the above glossary       variable   An item of data named by an identifier  Each variable has a type  such as int or Object  and a scope  See also class variable  instance variable  local variable

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The question is old but another important difference between a variable and a field is that a field gets a default value when it s declared A variable  on the other hand  must be initialized

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If your question was prompted by using JAXB and wanting to choose the correct XMLAccessType  I had the same question   The JAXB Javadoc says that a  field  is a non-static  non-transient instance variable   A  property  has a getter setter pair  so it should be a private variable    A  public member  is public  and therefore is probably a constant   Also in JAXB  an  attribute  refers to part of an XML element  as in  lt myElement myAttribute  first  gt hello world lt  myElement gt    It seems that a Java  property   in general  can be defined as a field with at least a getter or some other public method that allows you to get its value   Some people also say that a property needs to have a setter   For definitions like this  context is everything

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Variables are comprised of fields and non-fields    Fields can be either                                                       Static fields or  non-static fields also called instantiations e g  x   F     Non-fields can be either    local variables  the analog of fields but inside a methods rather than outside all of them  or parameters e g  y in x   f y    In conclusion  the key distinction between variables is whether they are fields or non-fields  meaning whether they are inside a methods or outside all methods    Basic Example  excuse me for my syntax  I am just a beginner   Class             fields          method1                            non-fields

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Actually these two terms are often used to represent same thing  but there are some exceptional situations  A field can store the state of an object  Also all fields are variables  So it is clear that there can be variables which are not fields  So looking into the 4 type of variables  class variable  instance variable  local variable and parameter variable  we can see that class variables and instance variables can affect the state of an object  In other words if a class or instance variable changes the state of object changes  So we can say that class variables and instance variables are fields while local variables and parameter variables are not   If you want to understand more deeply  you can head over to the source below -  http   sajupauledayan com java fields-vs-variables-in-java

[java] What is the difference between field, variable, attribute, and property in Java POJOs?

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