Can someone help.

This is correct:

public class Spaceship{
  private String shipType;

  public String getShipType() { 
        return shipType;
  }
  public void setShipType(String shipType) {
    this.shipType = shipType;
 }

The only change you have to make is public String shipType -> private String shipType.

Fields (shipType) have to be private, their accessors (getShipType, setShipType) have to be public.

That's because you have to use ship.getShipType() to get its value and ship.setShipType(type) to set its value. It is recommended to do so to ensure encapsulation and scalability.

Here are some solid reasons for using encapsulation in your code:

• Encapsulation of behaviour associated with getting or setting the property - this allows additional functionality (like validation) to be added more easily later.
• Hiding the internal representation of the property while exposing a property using an alternative representation.
• Insulating your public interface from change - allowing the public interface to remain constant while the implementation changes without affecting existing consumers.
• Controlling the lifetime and memory management (disposal) semantics of the property - particularly important in non-managed memory environments (like C++ or Objective-C).
• Providing a debugging interception point for when a property changes at runtime - debugging when and where a property changed to a particular value can be quite difficult without this in some languages.
• Improved interoperability with libraries that are designed to operate against property getter/setters - Mocking, Serialization, and WPF come to mind.
• Allowing inheritors to change the semantics of how the property behaves and is exposed by overriding the getter/setter methods.
• Allowing the getter/setter to be passed around as lambda expressions rather than values.
• Getters and setters can allow different access levels - for example, the get may be public, but the set could be protected.