Output is correct :(

Question about the task

Under discussion

Hello, I wrote this, it works fine (except for double multiplications like 6 * 6 * 6 but codegym says that it comes from additions so i don't think this is the problem) thanks :)

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; import java.util.ArrayList; import java.util.Arrays; public class Solution { public static TestString testString = new TestString(); public static void main(String[] args) { PrintStream consoleStream = System.out; ByteArrayOutputStream results = new ByteArrayOutputStream(); PrintStream stream = new PrintStream(results); System.setOut(stream); testString.printSomething(); String result = results.toString(); ArrayList<Object> terms = new ArrayList<>(Arrays.asList(result.split(" "))); ArrayList<Integer> onlyInt = new ArrayList<>(); for (Object o : terms) { } int operationResult = 0; for (int i = 0; i < terms.size(); i++) { Object o = terms.get(i); if (o == null) continue; if (o.toString().equals("*") && i > 0) { onlyInt.add(Integer.parseInt(terms.get(i - 1).toString()) * Integer.parseInt(terms.get(i + 1).toString())); terms.set(i - 1, null); terms.set(i, null); terms.set(i + 1, null); } } for (int i = 0; i < terms.size(); i++) { Object o = terms.get(i); if (o == null) continue; Integer term = null; try { term = Integer.parseInt(o.toString()); } catch (Exception ignored) {} if (o.toString().equals("-") && i < terms.size() - 1) { onlyInt.add(-Integer.parseInt(terms.get(i + 1).toString())); terms.set(i, null); terms.set(i + 1, null); } else if (o.toString().equals("+") && i < terms.size() - 1) { if (terms.get(i + 1) == null) continue; onlyInt.add(Integer.parseInt(terms.get(i + 1).toString())); terms.set(i, null); terms.set(i + 1, null); } else if (term != null) { onlyInt.add(term); } } for (Integer i : onlyInt) { operationResult += i; } System.setOut(consoleStream); result = result.substring(0, result.length() - 2) + operationResult; System.out.println(result); } public static class TestString { public void printSomething() { System.out.println("3 + 6 = "); } } }

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Wei Cui

Level 39 , Newark, United States

5 March 2020, 16:33

your method is too long and complicated, you should think about simplify and using StringBuilder is smarter way. try this one instead from line 25 to the end.

String result = results.toString();
StringBuilder sb = new StringBuilder(result); //put string into stringBUilder
String[] arr = result.split(" "); // make string array
int a = Integer.parseInt(arr[0]);  //using switch method find operation and determine outcome
int b = Integer.parseInt(arr[2]);
switch (arr[1]) {
    case "+":
        sb.append(a + b); // string + int is string , so don't need do anything
        break;

    case "-":
        sb.append(a - b);
        break;

    case "*":
        sb.append(a * b);
        break;
}
System.out.println(sb.toString());  //convert stringbuilder to string

SOUFIANE DAHIMI

Level 32 , Marrakech, Morocco

5 January 2020, 10:23

instead of doing all those things you could use the split(" ") method to transformyour result into an array of substring . then you can check the index 1(where there is the operator using a switch statement ). based on the result you can perform the operation by calling the parseInt() method on other string

Ivaylo Trifonov

Level 22 , Madrid, Spain

9 December 2019, 15:12

Hello, - FniJnn -. My suggest is, make it simply. Just read the String and use a regex to get rid of all the things You do not need. Then use regex one more time to verify what operation You need to perform (deletion, addition etc). Then You can use printf to show the result. : )