Say we want to make a tree. Therefore, we create the object: Tree.

tree java

in Java code:

Tree blackTree = new Tree();

A tree has a length of 5 cm:

normal tree javaIf you cut a three in half. The two halfs got a length, the moment that they were split. One way to deal with it is: delete the old object

delete tree java

create two new ones:

tree java

There are many ways to achieve this RESULT, one is correct:

  1. make a method in which you can edit the height
    package ConstructorExplanation;

public class Main {

	void start () {
		Tree upperHalf = new Tree();
		Tree lowerHalf = new Tree();
		upperHalf.addHeight(2.5);
		lowerHalf.addHeight(2.5);
	}
	
	public static void main(String[] args) {
		new Main().start();
	}

}
    		 
    package ConstructorExplanation;

public class Tree {
	double heightTree;
	
	void addHeight (double inputHeight) {
		heightTree = inputHeight;
	}

}

     

  2. only make a variable height in the object class
    package ConstructorExplanation;

public class Main {

	void start () {
		Tree upperHalf = new Tree();
		Tree lowerHalf = new Tree();
	}
	
	public static void main(String[] args) {
		new Main().start();
	}

}
    		 
    package ConstructorExplanation;

public class Tree {
	double heightTree = 2.5;
}

     

  3. make a constructor, now you can directly give the tree a height when you create the object.
     
    package ConstructorExplanation;

public class Main {

	void start () {
		Tree upperHalf = new Tree(2.5);
		Tree lowerHalf = new Tree(2.5);
	}
	
	public static void main(String[] args) {
		new Main().start();
	}

}
    		 
    package ConstructorExplanation;

public class Tree {
	double heightTree;
	
	Tree (double inputHeight) {
		heightTree = inputHeight;
	}

}

example summary

Point 3 is the best, in this case. Because at the moment you have cut the tree, the height of the two new objects is a fact, the moment you cut the tree.

  • It saves lines of code.
  • And height should be a variable as soon as possible
    • if you cut a three in half. The two halfs have a height the moment that they were split
    • Therefore, it should be a bit weird if you first create those objects without a height and after a while give them a height.