kambar bek

can i delete my profile completely? i dont' plan to use it. I have not used it that much.

please delete my profile

I learned this technique from a TA in college, it is called "using indicator variable" and the name pretty much says the essence of this technique.

the program below is coding bat exercise.i solved it

the question itself:

Return the sum of the numbers in the array, except ignore
sections of numbers starting with a 6 and extending to
the next 7 (every 6 will be followed by at least one 7).
Return 0 for no numbers.

public int sum67(int[] nums) { int sum = 0 ; boolean marker = false ; for(int i = 0 ; i < nums.length;i++){ if(nums[i] == 6 ){ marker = true ; } if(marker == false ){ sum += nums[i] ; } if(nums[i] == 7){ marker = false ;} } return sum ; }



Question:
1.is there other technique to avoid using "indicator variable" trick?
2.I suspect it is not "design patterns " that explains these little tricks. but I need to know all those little things.

what is the part of software development that describes these tricks/techniques to newbies? how is it called?
3. what books are there that give you list of those little techniques? or maybe tutorials? anything would be great! recommendations?

P.S. i would not be able to solve this problem another way , if i did not know indicator variable thing! So i want to know other ways of solving this problem!

does "continue " keyword have any effect here in this program?

public static void printer(int x[]){ System.out.println("printing in reverse order") ; for(int i = x.length-1; i > 0 ;i--){ if(x[i] == 13) { System.out.println("oh my god bad number - 13!!!!!!") ; continue ; } else System.out.println(x[i]) ; } }

is it diff. from the exact same program that does not have "continue" ?
public static void printer(int x[]){ System.out.println("printing in reverse order") ; for(int i = x.length-1; i > 0 ;i--){ if(x[i] == 13) { System.out.println("oh my god bad number - 13!!!!!!") ; //NO CONTINUE HERE! } else System.out.println(x[i]) ; } }

Hi, i have been solving codingbat exercises in java.

I consider myself a beginner and quite often i have to write each iteration with pen/paper to understand what i am doing, especially when using loops and recursion

as a wanna-be-efficient programmer, i suspect it is possible to automate this process,i.e. write some applet or function that you can give parameters and it will go through array/string and highlight every comparison/check step-by-step.

I already tried to google it, but did not find much, only this:http://en.wikipedia.org/wiki/File:Quicksort-example.gif


is there any educational applet/program that you can give parameters like array to go through, operation to do and it will highlight and show slow /fast speed visualization?

Question:
1. do you know software/applet that does it?
2. if not, this could be another idea - write my own project for myself/educational purposes; in this case, how can i do this?

I m used to see objects created in java like this:


DisplayTime x = new DisplayTime() ; // this is simple - "create object x of type Displaytime" //however, today i see this on some tutorial: //* DisplayTime x = new DisplayTime(new Calendar()) ; // this is some nested object


questions:

what does it mean when we create object like in * - this nested thing?

can we do something like this:


DisplayTime x = new DisplayTime(new Calendar(new Player(new Gambler(new Weather(...............))))) - and so on?

if yes, how many times can we nest it? and what does it mean if i see 3 or more objects created, nested in each other?

i m really confused about what created where / who creates what

can someone explain?

I m doing coding bat exercises;

to do debugging - i add many System.out.println() statements,

i m tired of writing it many times.


My question:

is there a shortcut or quick way to write this print statement quickly? if so, how?

hi , i ve been programming for 3 years now , but i still have this question:

suppose my code looks like this:


if( .....){ } if(.....){ } if(.....){ }

how is code above diff from this below:
if( .....){ } else if(.....){ } else if(.....){ }


is there any difference? i suspect no

actual question:
Given two strings, return true if either of the strings appears at the very end of the other string, ignoring upper/lower case differences (in other words, the computation should not be "case sensitive"). Note: str.toLowerCase() returns the lowercase version of a string.

endOther("Hiabc", "abc") → true
endOther("AbC", "HiaBc") → true
endOther("abc", "abXabc") → true

my solution:
public class endOtherClass{ public static void main(String args[]) { boolean is = endOther("yz","12xz") ; System.out.println(is) ; } public static boolean endOther(String a, String b) { a = a.toLowerCase() ; b = b.toLowerCase() ; if( a.length() == b.length()){ System.out.println("a and b have same length!") ; if(a.equals(b)){ System.out.println("wow, even better - they are exact same") ; return true ; } else { System.out.println("but are diff!") ; return false ; } } String shorter = "" ;// figure out which - a or b - is shorter String longer = "" ;// and which one is longer if( a.length() > b.length() ){ shorter = b ; longer = a ;} else { shorter = a ; longer = b ;} int offset = longer.length() - shorter.length() ; // the offset is used to know where exactly to start comparing //go through the shorter and compare the corresponding part of the longer string for(int i = 0 ; i < shorter.length() ; i++){ System.out.println("comparing subs: " + shorter.substring(i,i+1) + " and " + longer.substring(offset+i, offset+i+1)) ; if( !shorter.substring(i,i+1).equals( longer.substring(offset+i, offset+i+1) ) ){ //we add offset so we can start comparing the last n characters of shorter string! System.out.println("something wrong in long: " + longer.substring(offset+i, offset+i+1)) ; System.out.println("something wrong in short: " + shorter.substring(i,i+1)) ; return false ; } } return true ; } }



===============================================
i m 90% sure this code can be simplified, but i don't know other logic or way of thinking about this simple exercise

can someone help me refactor it and make it smaller?

thanks guys, it was silly mistake


i found it after i did it


thanks every1

hi , i m doing coding bat exercises in java.
the question :

Given a string, if the first or last chars are 'x', return the string without those 'x' chars, and otherwise return the string unchanged.

withoutX("xHix") → "Hi"
withoutX("xHi") → "Hi"
withoutX("Hxix") → "Hxi"

my solution:
public String withoutX(String str) { if(str.length() < 1) return str ; if(str.length() == 1 && str.equals("x") ) return "" ; if( str.substring(0).equals("x") ){ if( str.substring(str.length()-1).equals("x") ) return str.substring(1,str.length()-1) ; else return str.substring(1) ; } else if( str.substring(str.length()-1).equals("x")) // * - my code does not go here return str.substring(0,str.length()-1) ; else return str ; }

what i don't get is why it never goes to * part of code

for example if the string given is "xHix" , it only deletes last x , but the first x is still there ,
and it gives wrong answer "xHi", but it should delete the first "x"

i realized the naming for variables is not good enough, i used too many "number" in methods and variable names, (((

but it is ok, i m done anyways! ))

[Erjan Kenjegalee, please do not use profanity in your posts here. I have removed the offending word.]

thanks to everyone posted in this topic, i got it done, using NUMERIC approach, and using / and % as the exercise tells us

i needed to know how many digits the given number has, so i wrote the method for this.

public class ex_6_22{ public static int quotient(int a, int b){ return a / b ; } public static int modulus(int a, int b){ return a % b ; } public static String displayDigits(int number){ //displayDigits(4562) => prints 4 5 6 2 //number [1 - 99999] String result = "" ; if(number / 10 == 0){ result += number ; // 1 digit return result ; } else if(number / 100 == 0 ){ //2 digit int temp = number % 10 ; result += number / 10 + " " + temp ; return result ; } else if(number / 1000 == 0){//3 digit int num1 = number % 10 ; int num2 = (number % 100) / 10 ; int num3 = number / 100 ; result += num3 + " " + num2 + " " + num1 ; return result ; } else if(number / 10000 == 0){// 4 digit int num1 = number % 10 ; int num2 = (number % 100) / 10 ; int num3 = (number % 1000) / 100 ; int num4 = number / 1000 ; result += num4 + " " + num3 + " " + num2 + " " + num1 ; return result ; } else if(number / 100000 == 0){ // 5 digit int num1 = number % 10 ; int num2 = (number % 100) / 10 ; int num3 = (number % 1000) / 100 ; int num4 = (number % 10000) / 1000 ; int num5 = number / 10000 ; result += num5 + " " + num4 + " " + num3 + " " + num2 + " " + num1 ; return result ; } else return "" ; } public static int how_many_digits_in_this_number(int number){ //this method returns how many digits are in the given number // the number is in range [1-99999] int quotient_check = 10000 ;//the biggest number is 99999 - 5 digit int digits = 5 ; //start with the most digits in number while( number / quotient_check == 0){ quotient_check /= 10 ; digits-- ; }// e.g. 5678 / 100000 = 0 , so we decrease quotient check until //we hit the first digit of the number, e.g. 5678 / 1000 = 5, so it is 4 digit number! return digits-1 ; } public static String displayDigits2(int number){ int number_of_digits_in_given_number = (int) Math.pow(10, how_many_digits_in_this_number(number)) ; String result = "" ; while( number_of_digits_in_given_number != 0 ){ result += quotient(number, number_of_digits_in_given_number) + " " ;//add 2 spaces as the exercise tells! number = modulus(number, number_of_digits_in_given_number) ; number_of_digits_in_given_number = number_of_digits_in_given_number / 10 ; } return result ; } public static void main(String[] args) { System.out.println(displayDigits2(4568)) ; } }

again, thanks to all of you guys, one more exercise is done! )))

i need to write method displayDigits that displays digits with 2 spaces between each digit

e.g. 4562 should be "4 5 6 2"

method accepts digits in range 1 - 99999, i have it done, but i implemented the code in a "stupid manner"

I have WORKING CODE , how do i refactor it to use while loop?

public class ex_6_22{ public int quotient(int a, int b){ return a / b ; } public int modulus(int a, int b){ return a % b ; } public static String displayDigits(int number){ //displayDigits(4562) => prints 4 5 6 2 //number [1 - 99999] String result = "" ; if(number / 10 == 0){ result += number ; // 1 digit return result ; } else if(number / 100 == 0 ){ //2 digit int temp = number % 10 ; result += number / 10 + " " + temp ; return result ; } else if(number / 1000 == 0){//3 digit int num1 = number % 10 ; int num2 = (number % 100) / 10 ; int num3 = number / 100 ; result += num3 + " " + num2 + " " + num1 ; return result ; } else if(number / 10000 == 0){// 4 digit int num1 = number % 10 ; int num2 = (number % 100) / 10 ; int num3 = (number % 1000) / 100 ; int num4 = number / 1000 ; result += num4 + " " + num3 + " " + num2 + " " + num1 ; return result ; } else if(number / 100000 == 0){ // 5 digit int num1 = number % 10 ; int num2 = (number % 100) / 10 ; int num3 = (number % 1000) / 100 ; int num4 = (number % 10000) / 1000 ; int num5 = number / 10000 ; result += num5 + " " + num4 + " " + num3 + " " + num2 + " " + num1 ; return result ; } else return "" ; } public static void main(String[] args) { String res = displayDigits(48764) ; System.out.println(res) ; } }

the code below generates a question on number multiplication (inside applet)
e.g. - "what is 5 times 6"

the user enters answer and clicks button - if he is right, "very good " is displayed and a new string (question) is shown
or "try again" is shown and he has to answer it again


this is a WORKING CODE, i only need to make generate_question() and check_answer() methods to get called from paint() method

I DON'T HAVE paint() coded yet - i m asking you guys how to do it?

paint() should look like this - paint(Graphics g) {......}

-------------------------------------
Java how to program chapter 6, 4ed, ex 6.31

import javax.swing.* ; import java.awt.* ; import java.awt.event.* ; public class ex_6_31 extends JApplet implements ActionListener{ public void check_answer(int a, int b, int answer){ if( answer == a * b) { answerArea.setText("very good!") ; generate_new_question() ; //ask new question again! } else answerArea.setText("try again!") ; //no new question - keep same question! } public void generate_new_question(){ a = 1 + (int) (Math.random() * 9 ) ; // numbers are btw 1-9 b = 1 + (int) (Math.random() * 9 ) ; String question = "" ; question += "What is " + a + " times " + b + " ?" ; questionArea.setText(question) ; } int a ; int b ; JTextField answerField; JButton answerButton ; JTextArea questionArea ; JTextArea answerArea ; public void init(){ Container c = getContentPane() ; c.setLayout(new FlowLayout()) ; questionArea = new JTextArea() ; questionArea.setEditable(false) ; questionArea.setText("") ; // textarea where question is displayed c.add(questionArea) ; answerField = new JTextField(4) ; c.add(answerField) ; answerButton = new JButton("Answer!") ; answerButton.addActionListener(this) ; c.add(answerButton) ; answerArea = new JTextArea() ; //where "very good" or "try again" is shown answerArea.setEditable(false) ; answerArea.setText("") ; c.add(answerArea) ; generate_new_question() ; //called when the applet just starts - in the very beginning } public void actionPerformed(ActionEvent e){ int result = Integer.parseInt(answerField.getText()) ; check_answer(a, b, result) ; } }

i m writing a java applet that accepts 4 parameters to draw a rectangle - x, y, width, height

my problem is, i don't know how to call it in another method - square of asterisks,

it needs a variable Graphics g to be supplied, but i don't know where to give this "g" variable!

import java.awt.* ; import java.awt.event.* ; import javax.swing.* ; public class ex_6_21 extends JApplet implements ActionListener{ public void squareOfAsterisks(Graphics g, int x,int y, int width, int height){ super.paint(g) ; g.fillRect(x,y,width,height) ; } JTextField x,y,width, height ; JTextArea outputArea ; public void init(){ Container c = getContentPane() ; c.setLayout(new FlowLayout()) ; x = new JTextField(4) ; x.setEditable(true) ; c.add(x) ; y = new JTextField(4) ; y.setEditable(true) ; c.add(y) ; width = new JTextField(4) ; width.setEditable(true) ; c.add(width) ; height = new JTextField(4) ; height.setEditable(true) ; height.addActionListener(this) ; c.add(height) ; outputArea = new JTextArea() ; outputArea.setText("") ; c.add(outputArea) ; } public void actionPerformed(ActionEvent e){ int x_i = Integer.parseInt(x.getText()) ; int y_i = Integer.parseInt(y.getText()) ; int width_i = Integer.parseInt(width.getText()) ; int height_i = Integer.parseInt(height.getText()) ; Graphics g ; squareOfAsterisks( Graphics g, x_i, y_i, width_i, height_i) ; } }

here is the problem, how to initialize Graphics g variable?

Graphics g ; squareOfAsterisks(Graphics g, x_i, y_i, width_i, height_i) ;