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<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?
This question is related to
java
bufferedreader
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");
}
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!
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 -> {
System.out.println(s);
// do more stuff with s
}
);
} catch (IOException exc) {
exc.printStackTrace();
}
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 -> {
//...
});
or if you need to process it with given order:
reader.lines().forEachOrdered(line -> {
//...
});
You can use a structure like the following:
while ((line = bufferedReader.readLine()) != null) {
System.out.println(line);
}
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
Source: Stackoverflow.com