Please helpp

Question about the task

Let's put together a rectangle

Java Syntax, Level 5, Lesson 7

Under discussion

Can someone please help me.. I'm stuck creating a copy of another rectangle passed as an argument :(

Create a Rectangle class. The data for this class will be top, left, width, height.
Create as many initialize(...) methods as possible

Here are some examples:
- 4 parameters are specified: left, top, width, and height
- width/height is not specified (both are 0)
- height is not specified (it is equal to the width), we'll create a square
- create a copy of another rectangle passed as an argument

Requirements:

The program must not read data from the keyboard.
The Rectangle class must have int variables top, left, width and height.
The class must have at least one initialize method.
The class must have at least two initialize methods.
The class must have at least three initialize methods.
The class must have at least four initialize methods.

package com.codegym.task.task05.task0513; /* Let's put together a rectangle */ public class Rectangle { public int left; public int top; public int height; public int width; public void initialize(int left, int top, int height, int width){ this.left = left; this.top = top; this.height = height; this.width = width; } public void initialize(int left, int top){ this.left = left; this.top = top; } public void initialize(int left, int top, int height){ this.left = left; this.top = top; } public void initialize(Rectangle(int left, int top, int height, int width)){ this.left = left; this.top = top; this.height = height; this.width = width; } public static void main(String[] args) { } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

28 December 2018, 05:52

Its been awhile since i have done this, but i think the answer you are looking for is here:

public void initialize(int left, int top){
   this.left = left;
   this.top = top;
   height = 0;
   width = 0;
  // requirements say "width/height is not specified (both are 0)"
}
public void initialize(int left, int top, int height){
   this.left = left;
   this.top = top;
   this.height = height;
   width =height
  // requirements say "height is not specified (it is equal to the width), we'll create a square"
}
// ↓ just like declaring an object without the = new ..... , this is how you pass one ↓
public void initialize(Rectangle tempRec){
   tempRec.left = left;
   tempRec.top = top;
   tempRec.height = height;
   tempRec.width = width;
} // then set each property of the passed rectangle to this one.

If you haven't figured it out yet, the 'this' keyword only needs to be used when variables in the method have the same name as the property variables of the class. Anyways. I hope this helps. Good luck with your continued mastery of java!

Jason Ahn

Level 5 , Calgary, Canada

28 December 2018, 07:29

Thank you so much! Hope I survive til i reach 20 like you :)

Guadalupe Gagnon

Level 37 , Tampa, United States

28 December 2018, 14:30

You will. Once you start to "get" these concepts, the higher level stuff is just applying them. For me, a lot of practice and tinkering really helped cement them. One thing I like to do is time code. You can very easily time with three lines of code:

long start = System.currentTimeMillis();// at the top
 /* all code you want timed*/
 long finish = System.currentTimeMillis();//at the end
 /* long is the same as an int, but larger, the variable names start/finish
 can be anything you want. System.cuurenTimeMillis() returns a long
 that is the miliseconds of the day (1000 = 1 second)*/

System.out.println("Time took: " + finish-start);
// ↑this will print the time for you in milliseconds that the code ran

Once you have timed some code, try to improve it by changing data types, different operations, different order of declaring variables, using classes, changing arrays to arraylists or hashmaps. I know right now that is probably way overwhelming, but you will learn it all soon enough.

Niket

Level 8 , Kolkata, India

15 January 2019, 04:31

you rock man

Jacek

Level 13 , Warsaw, Poland

15 January 2019, 15:02

System.out.println("Time took: " + finish-start); it will not be calculated. After the "Time took: " (String) finish and start also will be String.

Guadalupe Gagnon

Level 37 , Tampa, United States

15 January 2019, 15:09

System.out.println("Time took: " + (finish-start));

↑ fix

Nicholas Peterson

Level 25 , Melbourne, Australia

15 April 2019, 13:50

Guadalupe, you are wrong. It must be: public void initialize(Rectangle anotherRectangle){ this.left = anotherRectangle.left; this.top = anotherRectangle.top; this.height = anotherRectangle.height; this.width = anotherRectangle.width; You are passing the object with parameters and new object gets them by means of calling initialize method.

Guadalupe Gagnon

Level 37 , Tampa, United States

15 April 2019, 13:58

@Nicholas Ooops. That was an answer a long time ago. My bad. I was hit and miss back then, and this one was a miss. On the code you shared, though not technically wrong, you do not need the 'this' keyword as there are no naming conflicts. You only need 'this' in situations where the local variable name clashes (is the same exact) as the class variable name. In this case the class variable for one (as example) is left and the local variable is anotherRectangle.left. the keyword 'this' is used for other purposes as well, but you will learn about that in subsequent lessons.