I have files containing text in pattern like this
Type:status
Origin:some text
Text:some text
URL:some url
Time:time
around 500 lines with same pattern. I want to extract only the text part from it. I tried reading the file with BufferedReader and used indexOf("Text") and indexOf("URL") and subString(i,j) but its giving exception at run time. How can I do this. My code:
FileReader fr = new FileReader("test.txt");
BufferedReader br = new BufferedReader(fr);
FileWriter wr = new FileWriter("new.txt");
// char buffer[] = null;
String s;
String str="";
BufferedWriter bw = new BufferedWriter(wr);
while ((s = br.readLine()) != null) {
str= str + s;
i = str.indexOf("Text:");
j= str.indexOf("URL:");
String a= str.substring(i, j);
bw.write(a);
}
br.close();
bw.close();
The "Text:" is found first in the 3rd line and "URL:" in the 4th, but if your program doesn't find both strings, it throws an exception.
Even if it worked you would find the same text over and over again.
Try something like this:
FileReader fr = new FileReader("test.txt");
BufferedReader br = new BufferedReader(fr);
FileWriter wr = new FileWriter("new.txt");
String s;
BufferedWriter bw = new BufferedWriter(wr);
while ((s = br.readLine()) != null) {
if (s.startsWith("Text:"))
bw.write(s);
}
br.close();
bw.close();
You could use
String[] pieces = str.split(":");
That will give you an array of strings split by what ever you put in the parenthesis. Then if you know the pattern you can get each piece out by iterating through it in a loop. For example: if you know that Type is at [0] and six things in each sequence you can say that the next Type will be at [6] and so on.
You should check for indexes. Of i and j. If one line is wrong, it will skip it and print the line that is wrong to the console. You should probably handle it in a different way but keep in mind that substring shouldn't love indexes of -1.
FileReader fr = new FileReader("test.txt");
BufferedReader br = new BufferedReader(fr);
String tokenText = "Text:";
String tokenURL = "URL:";
FileWriter wr = new FileWriter("new.txt");
// char buffer[] = null;
String s;
String str="";
BufferedWriter bw = new BufferedWriter(wr);
while ((s = br.readLine()) != null) {
String a;
str = str + s;
i = str.indexOf(tokenText);
j = str.indexOf(tokenURL);
if (i < 0 && j >= 0){
// pad with the token string
a = s.substring(j + tokenURL.length);
} else if(i >= 0) {
// pad with the token string
a = s.substring(i + tokenText.length);
} else {
System.out.printl("Unparsed line:");
System.out.printl(s);
}
bw.write(a);
}
br.close();
bw.close();
That said, as jonhchen902 said in the comments, you could also check for the strings after the while loop. It really depends on your input file and if you're expecting to find the "string" multiple times or once.
According to your example, Text: and Url: are on consecutive lines.
Your problem is you're reading the file line by line (br.readLine()), so calling indexOf() will most of the time return -1 in i or j (and you will never find both strings, since they aren't on the same line).
As the javadoc of substring() states, calling the method with a negative start index will throw an IndexOutOfBoundsException. So your approach isn't right.
You should instead parse the file line by line as you're doing, and simply test for a positive index to the call to indexOf("Text:"), and then substring the current line starting at the returned index + 5.
Not tested:
while ((line = br.readLine()) != null) {
i = line.indexOf("Text:");
if (i > 0) {
String text = line.substring(i);
bw.write(text + "\n");
}
}
Related
I have a text file like this:
Emma,F,20355
Olivia,F,19553
Sophia,F,17327
Ava,F,16286
Isabella,F,15504
Mia,F,14820
Abigail,F,12311
Emily,F,11727
I am trying to remove words after , and also put two lines in one line for every two lines.
For example:
Emma Olivia
Sophia Ava
Isabella Mia
Abigail Emily
The program can do the first part, but I don't know how the program can do the second part. I can split the words and numbers after first ,, but I got stuck how I can can arrange lines.
Here is the code:
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String currentLine;
String[] a;
String res;
while ((currentLine = reader.readLine()) != null) {
a = currentLine.split(",");
res = a[0] + "\n";
writer.write(res);
}
writer.close();
reader.close();
I think I need to create a for loop inside while loop, but I am not sure what to write to count even or odd lines.
Change to to something like this :
int count = 1;
while ((currentLine = reader.readLine()) != null) {
a = currentLine.split(",");
res = a[0] + count % 2 == 0 ? "\n" : " ";
count++;
writer.write(res);
}
try (
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile))
) {
while (true) {
String line1 = reader.readLine();
if (line1 == null) {
break;
}
writer.write(line1.split(",", 2)[0]);
String line2 = reader.readLine();
if (line2 == null) {
writer.newLine();
break;
}
writer.write(" " + line2.split(",", 2)[0]);
writer.newLine();
}
}
int newLine = 1;
while ((currentLine = reader.readLine()) != null) {
a = currentLine.split(",");
if (newLine % 2 == 0)
res += a[0] + "\n";
else
res += a[0] + " ";
newLine++;
}
writer.write(res);
Try reading two lines in at the same time if there is a second line left in the reader.
Something like this:
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String currentLine;
String[] a;
String[] b;
String res;
while ((currentLine = reader.readLine()) != null) {
a = currentLine.split(",");
if (reader.hasNext()) {
b = reader.readLine().split(",");
res = a[0] + " " + b[0] + "\n";
} else {
res = a[0]+"\n";
}
writer.write(res);
}
writer.close();
reader.close();
As mentioned above, read in two lines at a time. Combine them, then split based on the delimiter (comma) - Should then be easy to write out new format to a text file (Maybe pop the results in a list, then iterate over the list to write it out.
This is not a complete solution, but should be enough for you to get the idea.
// Read two lines at a time
String currentLine = reader.readLine(); //Emma,F,20355
String nextLine = reader.readLine(); //Olivia,F,19553
String combinedLine = currentLine + "," + nextLine;
// split into separate elements
String[] elements = combinedLine.split(",");
List<String> newLines = new ArrayList<>();
newLines.add(elements[0] + " " + elements[3]);
for (final String line : newLines) {
// write to file
writer.write(res);
}
I want the results from 'name' and 'code' to be inserted into log.txt file, but if I run this program only the name results gets inserted into .txt file, I cannot see code results appending under name. If I do System.outprintln(name) & System.outprintln(code) I get results printed in console but its not being inserted in a file.Can someone tell me what am I doing wrong?
Scanner sc = new Scanner(file, "UTF-8");
BufferedReader br = new BufferedReader(new FileReader(file));
PrintWriter out = new PrintWriter(new FileWriter("log.txt", true));
while ((line = br.readLine()) != null) {
if (line.contains("text1")) {
String[] splits = line.split("=");
String name = splits[2];
for (int i = 0; i < name.length(); i++) {
out.println(name);
}
}
if (line.contains("text2")) {
String[] splits = line.split("=");
String code = splits[2];
for (int i = 0; i < code.length(); i++) {
out.println(code);
}
}
out.close()
}
File looks like:
Name=111111111
Code=333,5555
Category-Warranty
Name=2222222
Code=111,22
Category-Warranty
Have a look at this code. Does that work for you?
final String NAME = "name";
final String CODE = "code";
BufferedReader br = new BufferedReader(new FileReader(file));
PrintWriter out = new PrintWriter(new FileWriter("log.txt", true));
while ((line = br.readLine()) != null) {
String[] splits = line.split("=");
String key = splits[0];
String value = splits[1];
if (key.equals(NAME) || key.equals(CODE)) {
out.println(value);
}
}
out.close();
You have a couple of problems in your code:
you never actually assign the variables name and code.
you close() your PrintWriter inside the while-loop, that means you will have a problem if you read more than one line.
I don't see why this wouldn't work, without seeing more of what you are doing:
BufferedReader br = new BufferedReader(new FileReader(file));
PrintWriter out = new PrintWriter(new FileWriter("log.txt", true));
while ((line = br.readLine()) != null) {
if (line.contains("=")) {
if (line.contains("text1")) {
String[] splits = line.split("=");
if (splits.length >= 2) {
out.println(splits[1]);
}
}
if (line.contains("text2")) {
String[] splits = line.split("=");
if (splits.length >= 2) {
out.println(splits[1]);
}
}
}
}
out.flush();
out.close();
Make sure the second if condition is satisfied i.e. the line String contains "text2".
the following code will only read the first line of a text file and it will stop there. I've been experimenting with loops but i cannot get it to successfully update the line until there are no more lines in the file. can anyone help? thanks
public void readFile(){
try {
BufferedReader in = new BufferedReader(new FileReader("test1.txt"));
words = new ArrayList<Word>();
int lineNum = 1; // we read first line in start
// delimeters of line in this example only "space"
char [] parse = {' '};
String delims = new String(parse);
String line = in.readLine();
String [] lineWords = line.split(delims);
// split the words and create word object
for (int i = 0; i < lineWords.length; i++) {
Word w = new Word(lineWords[i]);
words.add(w);
}
lineNum++; // pass the next line
line = in.readLine();
in.close();
} catch (IOException e) {
}
}
Basically, you want to keep reading until you run out of lines, at which time BufferedReader will return null
char[] parse = {' '};
String delims = new String(parse);
String line = null;
while ((line = in.readLine()) != null) {
String[] lineWords = line.split(delims);
// split the words and create word object
for (int i = 0; i < lineWords.length; i++) {
Word w = new Word(lineWords[i]);
words.add(w);
}
lineNum++; // pass the next line
}
You should be managing your resources better, if you open it, you should make all reasonable attempts to close. Currently, if your code fails for some reason, the in.close line will never be called. Also, you shouldn't ignore exceptions
Luckily, in Java 8, this is easy to manage...
try (BufferedReader in = new BufferedReader(new FileReader("test1.txt"))) {
//...
} catch (IOException e) {
e.printStackTrace();
}
Take a closer look at Basic I/O, The try-with-resources Statement and BufferedReader JavaDocs, especially BufferedReader#readLine
You may also want to take a look at LineNumberReader ;)
while((line = in.readLine()) != null){
//process line
}
This nested statement reads a line from the BufferedReader and stores it in line. At the end of the file, readLine() will return null and stop the loop.
I have to compare two files ,line by line from a particular word in both files using java language.
I do not know , how to write a condition. Am trying to compare from line by line. But am unable to compare from the particular String.
The both files has the strings. It should start from a particular string and end comparing to a another particular string. My code is comparing two files line by line. but not from a particular string.
FileInputStream fstream = new FileInputStream("s2.txt");
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
FileInputStream ff1=new FileInputStream("s1.txt");
DataInputStream fin=new DataInputStream(ff1);
BufferedReader br1=new BufferedReader(new InputStreamReader(fin));
String line1 = null;
String line2 = null;
int flag = 1;
while(
(flag == 1)
&& ((line1 = br.readLine()) != null)
&& ((line2 = br1.readLine()) != null)
)
{
//if((line1.contains("(Center t)")) && (line2.contains("(Center t )")))
//&& (line2.contains("(Center t)"))
/*&&(line1.endsWith("ID: "))
&& (line2.endsWith(" ID: "))**///)
//{
if(!line1.equalsIgnoreCase(line2))
flag = 0;
//}
}
br.close();
br1.close();
System.out.println("flag "+flag);
}
catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
My code is comparing two files line by line. How to do from a particular word?
Anyone can help me?
Use StringUtils of Apache Commons Lang:
String subLine1 = StringUtils.substringBetween(line1, "Center t", "ID: ");
String subLine2 = StringUtils.substringBetween(line2, "Center t", "ID: ");
if(subLine1 != null && subLine1.equals(subLine2)) {
//the lines equals between 'Center t' and 'ID: '
//.....
}
http://commons.apache.org/proper/commons-lang/
I have to read a file and depending of the content of the last lines, I have to copy most of its content into a new file. Unfortunately I didn't found a way to copy first n lines or chars of a file in java.
The only way I found, is copying the file using nio FileChannels where I can specifiy the length in bytes. However, therefore I would need to know how many bytes the stuff I read needed in the source-file.
Does anyone know a solution for one of these problems?
Try this:
Scanner scanner = new Scanner(yourFileObject); // initialise scanner
then
for (int i = 0; i < amountOfLines; i++) {
String line = scanner.nextLine(); // get line excluding \n at the end
// handle here
}
OR, for n chars, rather than lines:
Pattern charPattern = Pattern.compile(".")
// java.util.regex.Pattern with any char allowed
for (int i = 0; i < amountOfChars; i++) {
char next = scanner.next(charPattern).toCharArray()[0];
// handle here
}
This is, in my opinion, by far the best and easiest to write way to get the first n chars/lines from a file.
You should use a BufferedReader and read N lines which you will write into a fileX. Then redo this process until you've splitted your file into several files.
Here's a basic example:
BufferedReader bw = null;
try (BufferedReader br = new BufferedReader(new FileReader(new File("<path_to_input_file>")))) {
String line = "";
StringBuilder sb = new StringBuilder();
int count = 0;
bw = new BufferedWriter(new FileWriter(new File("<path_to_output_file>")));
while ( (line = br.readLine()) != null) {
sb.append(line)
.append(System.getProperty("line.separator"));
if (count++ == 1000) {
//flush and close current content into the current new file
bw.write(sb.toString());
bw.flush();
bw.close();
//start a new file
bw = new BufferedWriter(new FileWriter(new File("<path_to_new_output_file>")));
//re initialize the counter
count = 0;
//re initialize the String content
sb = new StringBuilder();
}
}
if (bw != null && sb.length() > 0) {
bw.write(sb.toString());
bw.flush();
bw.close();
}
} catch (Exception e) {
e.printStacktrace(System.out);
}
Since you have performance as key quality attribute, use BufferedReader over Scanner. Here's an explanation about the performance comparison: Scanner vs. BufferedReader