I'm reading an html file like this:
try {
BufferedReader bufferReader = new BufferedReader(new FileReader(path));
String content;
while((content = bufferReader.readLine()) != null) {
result += content;
}
bufferReader.close();
} catch (Exception e) {
return e.getMessage();
}
And I want to display it in a GWT textArea, in which i give it to as a String. But the string loses indentations and comes out as a one-liner text. Is there a way to display it properly formatted (with indentations) ?
That's probably because readLine() chops off the end-of-line character(s). Add them yourself again for each line.
Besides that, use a StringBuilder instead of using += to a String in a loop:
try {
BufferedReader bufferReader = new BufferedReader(new FileReader(path));
StringBuilder sb = new StringBuilder();
String content;
while ((content = bufferReader.readLine()) != null) {
sb.append(content);
sb.append('\n'); // Add line separator
}
bufferReader.close();
} catch (Exception e) {
return e.getMessage();
}
String result = sb.toString();
Well, assuming your textArea understands HTML (I don't know GWT specifically), why don't you prefix it with <pre> then append </pre>?
You'll may still have to escape all the HTML special characters such as & to & and < to <.
It might be more efficient to use a FileReader instead--there's no reason why you have to read the text line-by-line. Like Jesper suggested, using a StringBuilder to build your String is more efficient. Also, with FileReader, you don't have to manually append any newlines:
StringBuilder sb = new StringBuilder();
FileReader in = null;
try {
in = new FileReader(path);
int read;
char buf[] = new char[4096];
while ((read = in.read(buf)) != -1) {
sb.append(buf, 0, read);
}
} catch (Exception e) {
return e.getMessage();
} finally {
in.close();
}
String result = sb.toString();
If your HTML happens to be XHTML, then one thing you can try is to put it into an XML parser such as jdom or dom4j, which usually has some "pretty-print" option.
Related
I tried concatenating 2 lines of text in a given text file and printing the output to the console. My code is very complicated, is there a simpler method to achieve this by using FileHandling basic concepts ?
import java.io.*;
public class ConcatText{
public static void main(String[] args){
BufferedReader br = null;
try{
String currentLine;
br = new BufferedReader(new FileReader("C:\\Users\\123\\Documents\\CS105\\FileHandling\\concat.file.text"));
StringBuffer text1 = new StringBuffer (br.readLine());
StringBuffer text2 = new StringBuffer(br.readLine());
text1.append(text2);
String str = text1.toString();
str = str.trim();
String array[] = str.split(" ");
StringBuffer result = new StringBuffer();
for(int i=0; i<array.length; i++) {
result.append(array[i]);
}
System.out.println(result);
}
catch(IOException e){
e.printStackTrace();
}finally{
try{
if(br != null){
br.close();
}
}catch(IOException e){
e.printStackTrace();
}
}
}
}
The text file is as follows :
GTAGCTAGCTAGC
AGCCACGTA
the output should be as follows (concatenation of the text file Strings) :
GTAGCTAGCTAGCAGCCACGTA
If you are using java 8 or newer, the simplest way would be:
List<String> lines = Files.readAllLines(Paths.get(filePath));
String result = String.join("", lines);
If you are using java 7, at least you can use try with resources to reduce the clutter in the code, like this:
try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
StringBuffer text1 = new StringBuffer (br.readLine());
StringBuffer text2 = new StringBuffer(br.readLine());
// ...
}catch(IOException e){
e.printStackTrace();
}
This way, resources will be autoclosed and you don't need to call br.close().
Short answer, there is:
public static void main(String[] args) {
//this is called try-with-resources, it handles closing the resources for you
try (BufferedReader reader = new BufferedReader(...)) {
StringBuilder stringBuilder = new StringBuilder();
String line = reader.readLine();
//readLine() will return null when there are no more lines
while (line != null) {
//replace any spaces with empty string
//first argument is regex matching any empty spaces, second is replacement
line = line.replaceAll("\\s+", "");
//append the current line
stringBuilder.append(line);
//read the next line, will be null when there are no more
line = reader.readLine();
}
System.out.println(stringBuilder);
} catch (IOException exc) {
exc.printStackTrace();
}
}
First of all read on try with resources, when you are using it you don't need to close manually resources(files, streams, etc.), it will do it for you. This for example.
You don't need to wrap read lines in StringBuffer, you don't get anything out of it in this case.
Also read about the methods provided by String class starting with the java doc - documentation.
I've been looking around on the Internet trying to figure out which could be the best way to read from text files which are not very long (the use case here involves small OpenGL shaders). I ended up with this:
private static String load(final String path)
{
String text = null;
try
{
final FileReader fileReader = new FileReader(path);
fileReader.read(CharBuffer.wrap(text));
// ...
}
catch(IOException e)
{
e.printStackTrace();
}
return text;
}
In which cases could this chunk of code result in inefficiencies? Is that CharBuffer.wrap(text) a good thing?
If you want to read the file line by line:
BufferedReader br = new BufferedReader(new FileReader(path));
try {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
}
String everything = sb.toString();
} finally {
br.close();
}
If you want to read the complete file in one go:
String text=new String(Files.readAllBytes(...)) or Files.readAllLines(...)
I would usually just roll like this. The CharBuffer.wrap(text) thing seems to only get you a single character ... File Reader docs
BufferedReader br = new BufferedReader(fr);
StringBuilder sb = new StringBuilder();
String s;
while((s = br.readLine()) != null) {
sb.append(s);
}
fr.close();
return sb.toString();
I'm performing certain commands through command prompt and storing the values in a text file.
wmic logicaldisk where drivetype=3 get deviceid > drive.txt
Now I want to read the string stored in the text file from my java file. When I try to do this:
try {
File file = new File("drive.txt");
FileReader reader = new FileReader(file);
BufferedReader in = new BufferedReader(reader);
int i=0;
while ((string[i] = in.readLine()) != null) {
System.out.println(string[i]);
++i;
}
in.close();
} catch (IOException e) {
e.printStackTrace();
}
I get the output as follows:
ÿþD[]E[]V[]I[]C[]E[]
how to avoid this?
while ((string[i] = in.readLine()) != null) {
System.out.println(string[2]);
}
over there you are missing the i++;
However I would advise you to use this structure: Use a ArrayList instead of an array, since this allows you to have a self-resizing structure, also instead in the while use the method ready(); from the BufferedRead in order to check the end from the document, at the end the for it's just to display the elements in String ArrayList.
ArrayList<String> string = new ArrayList<String>();
try {
File file = new File("drive.txt");
BufferedReader entrada;
entrada = new BufferedReader(new FileReader(file));
entrada.readLine();
while (entrada.ready()) {
string.add(entrada.readLine());
}
entrada.close();
} catch (IOException e) {
e.printStackTrace();
}
for (String elements : string) {
System.out.println(elements);
}
Why do you need a string array here? The size of the array may be wrong? Simply use a string instead of array. I tried this and works fine for me:
try {
String string;
File file = new File("drive.txt");
FileReader reader = new FileReader(file);
BufferedReader in = new BufferedReader(reader);
int i = 0;
while ((string = in.readLine()) != null) {
System.out.println(string);
++i;
}
in.close();
} catch (IOException e) {
e.printStackTrace();
}
If you are using eclipse IDE, change the encoding type. Go to Edit->Set Encoding-> Others->UTF-8.
I am using a txt file for my level desing. I use the below to take the contents and convert to string buffer, then iterate through the lines to generate my game objects.
The the problem is that it reads from top down and so I have to design my levels upside down for them to be right way around.
How can I change the stream to read the opposite way? Or write the lines to the String Builder the opposite way?
private static String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append((line + "\n"));
}
} catch (IOException e) {
Log.w("LOG", e.getMessage());
} finally {
try {
is.close();
} catch (IOException e) {
Log.w("LOG", e.getMessage());
}
}
return sb.toString();
You could just use sb.insert(0, line + "\n") instead of sb.append(line + "\n");.
This will always add new lines to the front of the string, not append it to the end. Should do exactly what you want and will be just as fast, because StringBuilder is made exactly for things like that.
Suppose I have an InputStream that contains text data, and I want to convert this to a String (for example, so I can write the contents of the stream to a log file).
What is the easiest way to take the InputStream and convert it to a String?
public String convertStreamToString(InputStream is) {
// ???
}
If you want to do it simply and reliably, I suggest using the Apache Jakarta Commons IO library IOUtils.toString(java.io.InputStream, java.lang.String) method.
This is my version,
public static String readString(InputStream inputStream) throws IOException {
ByteArrayOutputStream into = new ByteArrayOutputStream();
byte[] buf = new byte[4096];
for (int n; 0 < (n = inputStream.read(buf));) {
into.write(buf, 0, n);
}
into.close();
return new String(into.toByteArray(), "UTF-8"); // Or whatever encoding
}
String text = new Scanner(inputStream).useDelimiter("\\A").next();
The only tricky is to remember the regex \A, which matches the beginning of input. This effectively tells Scanner to tokenize the entire stream, from beginning to (illogical) next beginning...
- from the Oracle Blog
Since Java 9 InputStream.readAllBytes() even shorter:
String toString(InputStream inputStream) throws IOException {
return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8); // Or whatever encoding
}
Note: InputStream is not closed in this example.
You can use a BufferedReader to read the stream into a StringBuilder in a loop, and then get the full contents from the StringBuilder:
public String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
Full disclosure: This is a solution I found on KodeJava.org. I am posting it here for comments and critique.
A nice way to do this is using Apache commons IOUtils
IOUtils.toString(inputStream, string);