How can this return null?

Question about the task

Reading from a stream

Java Collections, Level 2, Lesson 4

Under discussion

sw.append("1") was just a debugging thing

Implement the getAllDataFromInputStream() method. It must return a StringWriter containing all of the data from the passed stream.
Under no circumstances should null be returned.
The main() method is not tested.

Requirements:

There must be a public static getAllDataFromInputStream(InputStream) method.
The getAllDataFromInputStream(InputStream) method must return a StringWriter.
The getAllDataFromInputStream(InputStream) method must return a StringWriter containing all of the data from the passed stream.
Under no circumstances should null be returned.

package com.codegym.task.task32.task3202; import java.io.*; public class Solution { public static void main(String[] args) throws IOException { StringWriter writer = getAllDataFromInputStream(new FileInputStream("testFile.log")); System.out.println(writer.toString()); } public static StringWriter getAllDataFromInputStream(InputStream is) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(is)); StringWriter sw = new StringWriter(); while (br.ready()){ sw.append(br.readLine()); } if (sw.equals(new StringWriter())) { //sw.equals(null) and sw==null always return false according to Intellij sw.append("1"); } return sw; } }

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Bartek Józefiak

Level 34 , Wrocław, Polska

25 May 2020, 15:40

import java.io.*; /* Reading from a stream */ public class Solution { public static void main(String[] args) throws IOException { StringWriter writer = getAllDataFromInputStream(new FileInputStream("testFile.log")); System.out.println(writer.toString()); } public static StringWriter getAllDataFromInputStream(InputStream is) throws IOException { try{ StringWriter stringWriter = new StringWriter(); BufferedReader reader = new BufferedReader(new InputStreamReader(is)); String line; while ((line = reader.readLine()) != null){ stringWriter.write(line); } reader.close(); return stringWriter; } catch (Exception e){ return new StringWriter(); } } }

Wei Cui

Level 39 , Newark, United States

19 March 2020, 22:57

here is my solution, just wrap whole part using try catch

try {
       StringWriter sw = new StringWriter();
       InputStreamReader isr = new InputStreamReader(is);

           int reader;
           while((reader = isr.read()) != -1) {
               sw.write(reader);
           }
           return sw;

       } catch (Exception e) {
           return new StringWriter();
       }

Yu-Ping Lin

Level 29

14 October 2019, 03:44

>> Try and catch to catch any exception, if the exception happen, in the catch part: return new StringWriter()

CapLand

Level 23 , Mentor, United States

16 August 2019, 19:25

Did you ever figure out how to get that last condition met? I'm struggling with the same thing.

Olek

Level 41 , Amsterdam, Netherlands

23 December 2019, 13:05

It worked for me when I changed IOException to Exception in catch.