Overloading a Java constructor using multiple methods

Question

I have a program assignment in class. I already understand the basics of overloading, but at some point I'm completely confused. How can I only infer from the method I'm trying to use? Ok, let me show you the code, than explain.

public class Box {
 private int length, width, height;

 public Box(int length){
  this.length=length;
  System.out.println("Line created with length of" + length + ".");
 }
 public Box(int length, int width){
  this.length = length;
  this.width = width;
  System.out.println("Rectangle created with the length of " + length + " ");
  System.out.println("and the width of " + width + ".");
 }
 public Box(int length, int width, int height){
  this.length=length;
  this.width=width;
  this.height=height;
  System.out.println("Box created with the length of " + length + ", ");
  System.out.println("the width of " + width + ", ");
  System.out.println("and the height of " + height +".");

 }
}


class BoxTest {

 public static void main(String[] args) {
  Box BoxObject1 = new Box(1,0,0);
  Box BoxObject2 = new Box(1,2,0);
  Box BoxObject3 = new Box(1,2,3);



 }

}

Ok now! How can I call the BoxTest class to output only what is given. For example, using Box BoxObject1, I want to output "Line created with length XX", and not the rest. For Box Box Object2, I want to output "A rectangle created with length XX and width XX". I am not sure what to add next for this. Any help would be greatly appreciated.

Answer 1

I think

  Box BoxObject1 = new Box(1,0,0);
  Box BoxObject2 = new Box(1,2,0);
  Box BoxObject3 = new Box(1,2,3);

means

  Box BoxObject1 = new Box(1);
  Box BoxObject2 = new Box(1,2);
  Box BoxObject3 = new Box(1,2,3);

constuctor ( 0 ).

Answer 2

Box BoxObject1 = new Box(1,0,0);
Box BoxObject2 = new Box(1,2,0);
Box BoxObject3 = new Box(1,2,3);

3 . , :

Box BoxObject1 = new Box(1);
Box BoxObject2 = new Box(1,2);
Box BoxObject3 = new Box(1,2,3);

Answer 3

:

Box BoxObject1 = new Box(1);
Box BoxObject2 = new Box(1,2);
Box BoxObject3 = new Box(1,2,3);

Answer 4

, , , . : , .

, int, :

        new Box(1);

public Box(int length).

Answer 5

, , :

public class Box {

    private int length, width, height;

    public Box(int length) {
        this.length = length;
        System.out.println("Line created with length of " + length + ".");
    }

    public Box(int length, int width) {
        this(length);
        this.width = width;
        System.out.println("and the width of " + width + ".");
    }

    public Box(int length, int width, int height) {
        this(length, width);
        this.height = height;
        System.out.println("and the height of " + height + ".");
    }

}

( , extraneon), , , .

public class Box {

    private int length, width, height;

    public Box(int... param) {
        if(param.length > 0) {
            length = param[0];
            System.out.println("Line created with length of " + length + ".");
        }
        if(param.length > 1) {
            width = param[1];
            System.out.println("and the width of " + width + ".");
        }
        if(param.length > 2) {
            height = param[2];
            System.out.println("and the height of " + height + ".");
        }
    }

}

:

public class Demo {

    public static void main(String[] args) {
        //new Box(1);
        new Box(1,2);
        //new Box(1,2,3);
    }
}

:

Line created with length of 1.
and the width of 2.

Answer 6

, , . , . , . Builder.

Answer 7

, :

, ( ), :

public class Box {
 private int length, width, height;

 public Box(int length){
  this.length=length;
  System.out.println("Line created with length of" + length + ".");
 }
 public Box(int length, int width){
  this(length); // calls Box(length)
  this.width = width;
  System.out.println("and the width of " + width + ".");
 }
 public Box(int length, int width, int height){
  this(length, width); // calls Box(length, width) which calls Box(length)
  this.height=height;
  System.out.println("and the height of " + height +".");    
 }
}    

, , , , , bugfixing (, , ). .

Pangea . :

// if no parameters are required and all are optional
Box box0 = new Box.Builder().build();
Box box1 = new Box.Builder().length(1).build();
Box box2 = new Box.Builder().length(1).width(2).build();
Box box3 = new Box.Builder().length(1).width(2).height(3).build();

// if length is required and others are optional - that your Box
Box box1 = new Box.Builder(1).build();
Box box2 = new Box.Builder(1).width(2).build();
Box box3 = new Box.Builder(1).width(2).height(3).build();

// For comparison - your constructors. It less obvious what is length, 
// width or height
Box box1 = new Box(1);
Box box2 = new Box(1,2);
Box box3 = new Box(1,2,3);

Answer 8

- . . - " ". , .

.

public class Box
{
    private int length, width, height;

    public Box(int length)
    {
        this(length, 0, 0);
    }
    public Box(int length, int width)
    {
        this(length, width, 0);
    }
    public Box(int length, int width, int height){
    this.length=length;
    this.width=width;
    this.height=height;
    System.out.println("Box created with the length of " + length + ", ");
    System.out.println("the width of " + width + ", ");
    System.out.println("and the height of " + height +".");
    }
    public static void main(String[] args)
    {
        Box BoxObject1 = new Box(1);
        Box BoxObject2 = new Box(1,2);
        Box BoxObject3 = new Box(1,2,3);
    }
}

.

morrison@odonata:~$ java Box
Box created with the length of 1, 
the width of 0, 
and the height of 0.
Box created with the length of 1, 
the width of 2, 
and the height of 0.
Box created with the length of 1, 
the width of 2, 
and the height of 3.
morrison@odonata:~$