Addition problems are not solved correctly.

Question about the task

Resolved

I tested it multiple times and it works fine, but the last condition is not met. Please help.

Replace the main method's System.outx object with your own reader wrapper similar to the one shown in the lesson.
Your reader wrapper should output the solution to the console.
Call testString's existing printSomething() method.
Restore the System.out variable back to the original stream.

Possible operations: + - *
Format of input and output: a [operator] b = c
Negative numbers, fractions, and unary operators (such as factorials and square roots) are not allowed.

Example output:
3 + 6 = 9

Requirements:

The Solution class must contain a TestString class.
The Solution class must have a public static TestString field called testString that is initialized immediately.
The TestString class must have a public void printSomething() method.
The TestString class's printSomething() method must display the string "3 + 6 = ".
The Solution class's main(String[] args) method must create a PrintStream object (use the PrintStream constructor with a ByteArrayOutputStream parameter).
The Solution class's main(String[] args) method should replace and then restore the console output stream (System.out).
The Solution class's main(String[] args) method must call testString's printSomething() method.
The Solution class's main(String[] args) method must modify the line printed by the printSomething() method, as per the task conditions, and output it to the console.

package com.codegym.task.task19.task1914; /* Problem solving */ import java.io.ByteArrayOutputStream; import java.io.PrintStream; public class Solution { public static TestString testString = new TestString(); public static void main(String[] args) { PrintStream consoleStream = System.out; ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); PrintStream stream = new PrintStream(outputStream); System.setOut(stream); testString.printSomething(); System.setOut(consoleStream); String result = outputStream.toString(); result = result.substring(0, result.length() - 2); String[] chars = result.split(" "); int number1 = Integer.parseInt(chars[0]); int number2 = Integer.parseInt(chars[2]); String operation = chars[1]; if (operation.equals("+")) System.out.println(result + (number1 + number2)); else if (operation.equals("-")) System.out.println(result + (number1 - number2)); else if (operation.equals("*")) System.out.println(result + (number1 * number2)); } public static class TestString { public void printSomething() { System.out.println("3 + 6 = "); } } }

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Anthony Chalk

Level 30 , London, United Kingdom

17 September 2020, 10:36

solution

I haven't managed to test your code but just looking at it, on line 22 your changing the String from "3 + 6 = " to "3 + 6 ". Meaning that at the end you're going to be printing "3 + 6 9". Not "3 + 6 = 9" You don't need line 22 at all.

Mateusz

Level 29 , Poland

17 September 2020, 11:25

Thanks for your reply, but unfortunately this line is correct. It deletes the "next line" character, which would make the result be displayed in two lines. So without this line "3 + 6 = 9" woud be displayed at the end.

Mateusz

Level 29 , Poland

17 September 2020, 11:50

Nevertheless, I tested what you suggested and it passed the verification. There must be a bug in the verification process cause now the displayed result is: "3 + 6 = 9"

Anthony Chalk

Level 30 , London, United Kingdom

17 September 2020, 12:00

If you want to delete new line characters, the regex for it is: \n - new line \r - carriage return

Mateusz

Level 29 , Poland

17 September 2020, 12:07

Yeah, all right, but you can also do it the way I did it on line 22 - simply delete the last character from the string. It works at least on my computer.