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Write a constructor in class Doctor to initialize the private field doctor_name [closed]

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Write a constructor in class Doctor to initialize the private field doctor_name. How can I write this?
class Doctor{
public Doctor(private String doc_name){
}
}

Here is an example class Doctor with a constructor.
class Doctor{
private String doc_name;
Doctor(String doc_name){
this.doc_name = doc_name;
}
}
You can also add a setter and getter to apply encapsulation.
class Doctor{
private String doc_name;
Doctor(String doc_name) {
this.doc_name = doc_name;
}
public void setDoctorName(String doc_name) {
this.doc_name = doc_name;
}
public String getDoctorName() {
return this.doc_name;
}
}
I've made a simple implementation of the class Doctor.
class Main {
public static void main(String[] args) {
Doctor doctor1 = new Doctor("Someone");
System.out.println(doctor1.getDoctorName());
doctor1.setDoctorName("Someone Else");
System.out.println(doctor1.getDoctorName());
}
}
Output:
Someone
Someone Else

how to share a variable inside actionListener (java) [closed]

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I'm trying to make a preference menu and trying to share a variable that is inside action listener. Thanks in advance
public void actionPerformed(ActionEvent e) {
if(e.getSource()==buttonp1) {
player_c=c1.getText();
if(player_c.equalsIgnoreCase("blue")) {
p1_color="blue";
//i want to share a String with another class.
}
if(player_c.equalsIgnoreCase("red")) {
p1_color="red";
}
if(player_c.equalsIgnoreCase("green")) {
p1_color="green";
}
}
}

Move the variable to a different class, and pass an instance to the listener (probably by lexical scope).
class Player {
private String color;
// ...
public void setColor(String color) {
this.color = Objects.requireNonNull(color);
}
}
// ...
Player p1 = ...;
// (Watch the repetition.)
blue.addActionListener(event -> {
p1.setColor("blue");
});
red.addActionListener(event -> {
p1.setColor("red");
});
green.addActionListener(event -> {
p1.setColor("green");
});
// ...

Java return Object [closed]

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I don’t know how to return the value of the string here, in short, I need the output of this string that is stored in the function:
public Object Directory(String directory) {
String directory1 = "directory";
return directory1;
}
public static void main(String... args) throws Exception {
System.out.println(directory1);
}
This is my interface in another file:
public interface Interface extends Remote {
Object FileName(String filename) throws RemoteException;
Object Directory(String directory) throws RemoteException;
}

If I understand you. You can try so.
public static String Directory(String directory) {
String directory1 = "directory";
return directory1;
}
public static void main(String... args) throws Exception {
System.out.println(Directory("directory1"));
}

In Java you must declare the return type of a function. In your case you have defined the return type of Object when you really want a return type of String

Unexpected NullPointerException [closed]

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Closed 8 years ago.
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How can NullReferenceException happen here:
public class DataContextBinder extends Binder {
private static final String DATA_CONTEXT = "DataContext";
// Fields
private final Listener<PropertyChangedEventArgs<Object>> dataContextListener = new Listener<PropertyChangedEventArgs<Object>>() {
#Override
public void onEvent(PropertyChangedEventArgs<Object> args) {
setSource(args.getNewValue());
}
};
// Constructors
protected DataContextBinder(Object target, String targetPropertyName,
Binding binding) {
super(Property.getPropertyValue(target, DATA_CONTEXT), target,
targetPropertyName, binding);
}
// Methods
protected void createListeners(Object source) {
Log.e("DataContextBinder", "DCL = " + dataContextListener.toString());
// It throws NullPointerException on dataContextListener.toString()
Property.addPropertyChangedListener(getTarget(), DATA_CONTEXT,
dataContextListener);
super.createListeners(source);
}
protected void removeListeners(Object source) {
Property.removePropertyChangedListener(getTarget(), DATA_CONTEXT,
dataContextListener);
super.removeListeners(source);
}
}

dataContextListener is null..

How do I write the class that contains the main function for this code? [closed]

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public class Soldier
{
private String soldierName;
public void setSoldierName( String name )
{
SoldierName = name;
}
public String getSoldierName()
{
return soldierName;
}
public void displayMessage()
{
System.out.printf( "The name of \n%s!\n",
getSoldierName() );
}
}

If you just want the class to have a main method, just add it as you would to any other class:
public class Soldier
{
private String soldierName;
public void setSoldierName( String name )
{
SoldierName = name;
}
public String getSoldierName()
{
return soldierName;
}
public void displayMessage()
{
System.out.printf( "The name of \n%s!\n",
getSoldierName() );
}
public static void main(String args[]) {
}
}
To actually do something useful in the main, you might want to create an instance of the class in there, set the soldier name and then call the displayMessage() method, for example. So like this:
public static void main(String args[]) {
Soldier soldier = new Soldier();
soldier.setSoldierName("John");
soldier.displayMessage();
}