I am unable to understand the getter and setter methods. Can anyone explain the use of these methods

Question

Can Anyone give application of these methods using a small example.

LandingActivity.java

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class LandingActivity extends Activity {

    public Button mThrustButton;
    public TextView mTypeLabel;
    public EditText mPassengersField;



    public Spaceship mSpaceship;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_landing);

        mThrustButton = (Button)findViewById(R.id.thrustButton);
        mTypeLabel = (TextView)findViewById(R.id.typeTextView);
        mPassengersField = (EditText)findViewById(R.id.passengersEditText);

        // Add your code here!


         mSpaceship= new Spaceship("FIREFLY"); 



    }
}

Spaceship.java

public class Spaceship {
    private String mType;
    private int mNumPassengers = 0;

    public String getType() {
      return mType;
    }

    public void setType(String type) {
      mType = type;
    }

    public int getNumPassengers() {
      return mNumPassengers;
    }

    public void setNumPassengers(int numPassengers) {
      mNumPassengers = numPassengers;
    }

    public Spaceship() {
      mType = "SHUTTLE";
    }

    public Spaceship(String type) {
      mType = type;
    }
}

Answer 1 · 2016-11-30T23:30:38Z

November 30, 2016 11:30pm

Kaushik;

That is a great question. Let's look at it from a high language level abstracted a bit away from strictly an Android setting.

getters and setters come out of one of the fundamental Object Oriented Programming (OOP) concepts called encapsulation. Encapsulation is a way of wrapping data (variables) and the coding doing something with that data (methods) together. We encapsulate class variables and hide them from other classes and make them accessible only through methods of the current class.

To achieve encapsulation in Java

Declare the variables of a class as private.
Provide public setter and getter methods to modify and view the variables values.

That sounds all great and, if you are anything like me, doesn’t really mean much without an example. So, let’s do that.

Employee.java

public class Employee{

   private String name;
   private String idNum;
   private int age;

   public int getAge(){
      return age;
   }

   public String getName(){
      return name;
   }

   public String getIdNum(){
      return idNum;
   }

   public void setAge( int newAge){
      age = newAge;
   }

   public void setName(String newName){
      name = newName;
   }

   public void setIdNum( String newId){
      idNum = newId;
   }
}

Obviously we would store much more about an employee, but this is just a sample. Now, to your question of how do you access and use this “hidden” data from another class.

RunEmployee.java

public class RunEmployee{

   public static void main(String args[]){
      Employee employee = new Employee();
      employee.setName("James");
      employee.setAge(20);
      employee.setIdNum("12343ms");

      System.out.print("Name: " + employee.getName() +
                       " | Age: " + employee.getAge() +  
                       " | Id: " + employee.getIdNum());
    }
}

If we were to run this we would get the following output:

Name: James | Age: 20 | Id: 12343ms

Some of the benefits of encapsulation include:

The fields of a class can be made read-only or write-only.
A class can have total control over what is stored in its fields.
The users of a class do not know how the class stores its data. A class can change the data type of a field and users of the class do not need to change any of their code.

Does that help at all? Please post back with further questions. Getters and Setters are an important concept in Java, as well as other languages, so getting a good grasp on them is important.

Happy coding,
Ken

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Mint Milano

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I am unable to understand the getter and setter methods. Can anyone explain the use of these methods

1 Answer

Ken Alger

Ken Alger

Mint Milano

Mint Milano