Using BufferedReader readLine in a while loop properly

Question

So I m having an issue reading a text file into my program  Here is the code        try          InputStream fis new FileInputStream targetsFile           BufferedReader br new BufferedReader new InputStreamReader fis               while br readLine    null           for int i 0 i lt 100 i                 String   words br readLine   split                   int targetX Integer parseInt words 0                int targetY Integer parseInt words 1                int targetW Integer parseInt words 2                int targetH Integer parseInt words 3                int targetHits Integer parseInt words 4                Target a new Target targetX  targetY  targetW  targetH  targetHits               targets add a                     br close              catch Exception e           System err println  Error  Target File Cannot Be Read            The file I am reading from is 100 lines of arguments  If I use a for loop it works perfectly  If I use the while statement  the one commented out above the for loop  it stops at 50  There is a possibility that a user can run the program with a file that has any number of lines  so my current for loop implementation won t work   Why does the line while br readLine    null  stop at 50  I checked the text file and there is nothing that would hang it up   I don t get any errors from the try-catch when I use the while loop so I am stumped  Anyone have any ideas

User · Accepted Answer

You re calling br readLine   a second time inside the loop  Therefore  you end up reading two lines each time you go around

User · Answer

Thank you to SLaks and jpm for their help  It was a pretty simple error that I simply did not see   As SLaks pointed out  br readLine   was being called twice each loop which made the program only get half of the values  Here is the fixed code   try          InputStream fis new FileInputStream targetsFile           BufferedReader br new BufferedReader new InputStreamReader fis            String words   new String 5           String line null          while  line br readLine     null               words line split                   int targetX Integer parseInt words 0                int targetY Integer parseInt words 1                int targetW Integer parseInt words 2                int targetH Integer parseInt words 3                int targetHits Integer parseInt words 4                Target a new Target targetX  targetY  targetW  targetH  targetHits               targets add a                     br close              catch Exception e           System err println  Error  Target File Cannot Be Read            Thanks again  You guys are great

User · Answer

also very comprehensive     try      InputStream fis new FileInputStream targetsFile       BufferedReader br new BufferedReader new InputStreamReader fis         for  String line   br readLine    line    null  line   br readLine             System out println line              br close      catch Exception e       System err println  Error  Target File Cannot Be Read

User · Answer

Concept Solution br read   returns particular character s int value so loop  continue s until we won t get -1 as int value and Hence up to there it prints  br readLine   which returns a line into String form         Way 1      while br read    -1                continues loop until we won t get int value as a -1       System out println br readLine                  Way 2      while  line br readLine     null              System out println line                Way 3      for String line br readLine   line  null line br readLine                System out println line           Way 4  It s an advance way to read file using collection and arrays concept  How we iterate using for each loop  check it here http   www java67 com 2016 01 how-to-use-foreach-method-in-java-8-examples html

User · Answer

In case if you are still stumbling over this question  Nowadays things look nicer with Java 8   try     Files lines Paths get targetsFile   forEach      s - gt          System out println s            do more stuff with s              catch  IOException exc      exc printStackTrace

User · Answer

You can use a structure like the following    while   line   bufferedReader readLine       null                System out println line

User · Answer

In addition to the answer given by  ramin  if you already have BufferedReader or InputStream  it s possible to iterate through lines like this   reader lines   forEach line - gt                    or if you need to process it with given order   reader lines   forEachOrdered line - gt

[java] Using BufferedReader.readLine() in a while loop properly

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