CodeGym/Help with Java Tasks/What does codegym want from me???? waaaaaa :((( the outpu...

Level 41

09.12.2020
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What does codegym want from me???? waaaaaa :((( the output is like in the examples provided yet it is not good. What the hell? Pls help :(((

Question about the task

Resolved

I have created the isDouble class which is from the previous FromHell exercise "Different methods for different types" which checks if a number has "." in it meaning it is a double. This class's method is used in line 75. What have I done wrong?

Read a URL from the console.
Display a space-delimited list of all the parameters (The parameters follow the "?" and are separated by "&", e.g. "lvl=15").
The URL contains at least 1 parameter.
The parameters must be displayed in the same order in which they are present in the URL.
If the obj parameter is present, pass its value to the relevant alert method.
alert(double value) - for numbers (fractional numbers have a decimal point)
alert(String value) - for strings
Note that the alert method must be called AFTER the list of all parameters is displayed.

Example 1

Input:
http://codegym.cc/alpha/index.html?lvl=15&view&name=Amigo

Output:
lvl view name

Example 2

Input:
http://codegym.cc/alpha/index.html?obj=3.14&name=Amigo

Output:
obj name double: 3.14

Requirements:

The program should read only one line from the keyboard.
The Solution class must not have static fields.
The program must display data on the screen in accordance with the task conditions.
The program should call the alert method with the double parameter if the obj parameter can be correctly converted to a double.
The program should call the alert method with the String parameter if the obj parameter CANNOT be correctly converted to a double.

package com.codegym.task.task15.task1527; import org.apache.commons.lang3.StringUtils; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import java.net.URL; import java.net.URLDecoder; import java.util.*; import java.util.regex.Matcher; import java.util.regex.Pattern; import static com.codegym.task.task15.task1527.IsDouble.isNumeric; import static java.util.regex.Pattern.LITERAL; /* Request parser */ public class Solution { public static void main(String[] args) { //write your code here BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String input = null; try { input = reader.readLine(); } catch (IOException e) { e.printStackTrace(); } URL url = null; String _Query = null; try { url = new URL(input); // get the Query _Query = url.getQuery(); // display the URL //System.out.println("URL = " + url); // display the Query //System.out.println(" Query= " + _Query); } // if any error occurs catch (Exception e) { // display the error System.out.println(e); } String[] arrOfStr = _Query.split("&"); List<String> newArrOfStr = new ArrayList<>(); //now i need to eliminate elements after = for (String it : arrOfStr) { if (it.contains("=")) { int index3 = it.indexOf("="); it = it.substring(0, index3); } System.out.print(it + " "); //this prints the elements of the array } System.out.println(); //so far it's correct for (String it1 : arrOfStr) { int index4 = it1.indexOf("="); newArrOfStr.add(it1.substring(index4+1)); } //now I have added to it2 the string after = . I must check if that string is a double for (String it2 : newArrOfStr) { if (isNumeric(it2)) { if (it2.contains(".")) { alert(Double.parseDouble(it2)); } } } } public static void alert(double value) { System.out.println("double: " + value); } public static void alert(String value) { System.out.println("String: " + value); } }

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Nouser

Level 36 , Germany

9 December 2020, 16:02

As with the other task where you use your regex hell... zero isn't giving the expected result obj=0 fails obj=0.0 works Numbers in scientific notation work neither (like -1e-10) dump that isNumeric check. It makes more problems than it solves and use parseDouble instead. declare a varibale where you can save the obj parameter vale

String objParamValue = null;

save all parametes of a Url in an array //or, if you do not want to use the URL class first do a split using ? and then use the the second element of the resulting array as query (result[1])

String[] params = url.getQuery().split("&");

loop through the array and if there is an obj parameter and it has a value save in for later usage

for (String s : params) {
    String[] parts = s.split("=");

here you can check, if parts[0] equals obj and if yes, if it has a value

if (parts[0].equals("obj") && parts.length > 1) objParamValue = parts[1];

and don't forget to output the parameter name After you output all the parameters you check if objParamValue is a double...

if (objParamValue != null) {
    try
    {
        alert(Double.parseDouble(objParamValue));

in the catch call the string alert. That's it...and you do not need crazy regex and String utils (don't know if the validator knows that, so better remove that from your imports)

Andrei

Level 41

10 December 2020, 10:29

I have tried your way Nouse, see below, in the second comment, the part in the /**/ comments. I have also tried another way using some of the code I had already written, but it doesn't work. The requirements are confusing. It says that for obj that are not double the string alert should be called, yet, in the OUTPUT CODEGYM PROVIDES, NO STRINGS ARE DISPLAYED.

package com.codegym.task.task15.task1527;

import org.apache.commons.lang3.StringUtils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.*;

/*
Request parser

*/

public class Solution {

    public static void main(String[] args) {
        //write your code here
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String input = null;
        try {
            input = reader.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }

        URL url = null;
        String _Query = null;
        try {
            url = new URL(input);
            _Query = url.getQuery();
        } catch (Exception e) {
            System.out.println(e);
        }

        String[] arrOfStr = _Query.split("&");

        //now i need to eliminate elements after =
        for (String it : arrOfStr) {
            if (it.contains("=")) {
                int index3 = it.indexOf("=");
                it = it.substring(0, index3);
            }
            System.out.print(it + " "); //this prints the elements of the array
        }
        System.out.println();
        //so far it's correct

Andrei

Level 41

10 December 2020, 10:29

List<String> newArrOfStr = new ArrayList<>();
        for (String it1 : arrOfStr) {
            int index4 = it1.indexOf("=");
            newArrOfStr.add(it1.substring(index4 + 1));
        }

        //now I have added to newArrOfStr the string after = . I must check if that string is a double

        for (String it3 : newArrOfStr) {
            try {
                Double.parseDouble(it3);
                if (it3.contains(".")) alert(Double.parseDouble(it3));
                else alert(it3);
            } catch (NumberFormatException e) {  }
        }
    }
/*
        String objParamValue = null;
        for (String it2 : arrOfStr){

            //iterating through arrOfStr which contains what comes after ? in the url
            //to split the what is before and after =
            String parts[] = it2.split("=");
            if (parts[0].equals("obj") && parts.length > 1) objParamValue = parts[1];
            if (objParamValue != null){
                try { alert(Double.parseDouble(objParamValue));
                } catch (NumberFormatException e){
                    alert((String) objParamValue);}
            }
        }
    }*/

    public static void alert(double value) {
        System.out.println("double: " + value);
    }

    public static void alert(String value) {
        System.out.println("String: " + value);
    }
}

Nouser

Level 36 , Germany

10 December 2020, 11:06

useful

the try catch can't work. In line 6 you call parseDouble for the first time. If it is a string, then you'll end immediatiely in the catch block. Means lines 7 - x won't get executed in case you have a string value. Line 7 is also problematic. If you hava as value 3, then this is a valid double value. Your code won't accept it. So in the end the code should look similar to... (and I used a place holder variable vor the objValue, later more, why)

try {
     alert(Double.parseDouble(objValue));
} catch (NumberFormatException e) {
      alert(objValue);
}

You see what happens? In line 2 parseDouble(objValue) is getting called. If it fails, cause it is a string, the code continues in the catch block and prints the string. If not, if the value is a double, the method call returns a double and calls the alert(double) method. Perfect. And you just should output the value if the parameter name is obj. Not for all parameter values... If the obj parameter is present, pass its value to the relevant alert method.

Nouser

Level 36 , Germany

10 December 2020, 11:10

Therefore you'd just need one loop and here you grab the value if obj has one, like

//introduce the variable to hold the object parameter value
//initialize it to null so we can compare to null later... otherwise you'd
//need an additional boolean
String objValue = null;
//now i need to eliminate elements after =
for (String it : arrOfStr) {
    if (it.contains("=")) {
        int index3 = it.indexOf("=");
        String itTemp = it;
        it = it.substring(0, index3);
        //why not check here, if it equals obj?
        if (it.equals("obj")) {
            //if there's no data after the = it will fail
            objValue = itTemp.substring(++index3);
        }
    }
    System.out.print(it + " "); //this prints the elements of the array
}

I added that to your code but you may really want to use split over substr. That'll make your live a lot easier. Now you just check if objValue is not null and use the above try-catch construct

Nouser

Level 36 , Germany

10 December 2020, 11:13

solution

And just to show you how it'll look without the usage of the URL class (here we do not really need it) and with split

String input = "";
try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
    input = reader.readLine();
} catch (IOException ioe) {
    ioe.printStackTrace();
}

//Either create java.net.URl obj or just split the url using ? to get the query
//URL url = new URL(input);
String[] query = input.split("\\?");
String objParameterValue = null;

//for (String parameter : url.getQuery().split("&")) {
for (String parameter : query[1].split("&")) {
    String[] parameterParts = parameter.split("=");
    System.out.print(parameterParts[0] + " ");
    if (parameterParts[0].equals("obj") && parameterParts.length > 1)
        objParameterValue = parameterParts[1];
}

System.out.println();

if (objParameterValue != null) {
    try
    {
        alert(Double.parseDouble(objParameterValue));
    }
    catch(NumberFormatException ignore) {
        alert(objParameterValue);
    }
}

Andrei

Level 41

10 December 2020, 17:44

In the line below, where is it storing what comes after the "&" ? Because you are looping through a string not a string[] to be able to store both values after splitting.

for (String parameter : query[1].split("&")) {

Andrei

Level 41

10 December 2020, 18:07

useful

I have finally managed to sort it out. Thank you very much for your assistance, it takes a village to raise a child. :)

public class Solution {

    public static void main(String[] args) {
        //write your code here
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String input = null;
        try {
            input = reader.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }

        String[] query = input.split("\\?");
        String objParameterValue = null;

        String parameter[] = query[1].split("&");
        for (int i = 0; i < parameter.length; i++) {
            String[] parameterParts = parameter[i].split("=");
            System.out.print(parameterParts[0] + " ");
            if (parameterParts[0].equals("obj") && parameterParts.length > 1)
                objParameterValue = parameterParts[1];
            }
        System.out.println();

        if (objParameterValue!= null){
        try {
            alert(Double.parseDouble(objParameterValue));
        }catch (NumberFormatException e){alert((String) objParameterValue);}
      }
    }

    public static void alert(double value) {
        System.out.println("double: " + value);
    }

    public static void alert(String value) {
        System.out.println("String: " + value);
    }
}

Nouser

Level 36 , Germany

10 December 2020, 18:14

excellent, and to your question above... split returns an array and instead of saving the array in a variable I just gave the array to the for each loop

for (String parameter : query[1].split("&")) {

is the same as

String[] parameters = query[1].split("&");
for (String parameter : parameters) {

So you loop through the entire parametes array and each iteration is saved in parameter.

Andrei

Level 41

10 December 2020, 18:21

aaaaa, ok, so actually query[1].split("&") is a 2 value array, parameter takes the first value, executes the code block between { } and then returns for the 2nd value; Sehr gut, vielen dank!