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Am having a txt file. which is having line like
if(true) return true;
I need to get the sub string from preceding spaces that is
" if(true) "
and another sub string as
" retrun true; "
I am reading this line using scanner class and assign to a string. from that string am converting it into toCharArray. I have tried using toCharArray[] but the spaces are ignored. How to get the substring from the preceding spaces using toCharArray
kindly anybody help me to get a solution for this issue
Thanks in advance.
You can use StringReader:
String str = "Some String";
int numberOfChars = str.length();
StringReader sr = new StringReader(str);
char[] chars = new char[numberOfChars];
int i = 0, read = 0;
try {
while ((read = sr.read()) != -1) {
chars[i] = (char)read;
i++;
}
} catch (IOException e) {
// handle the exception
}
This will read all the characters, without skipping any of them.
EDIT:
Now that I understand what you are trying to do, I would recommend you to define a grammar for your instructions. In this way you should be able to identify these 2 separate statements or instructions. I would suggest you to use a compiler building tool for that like e.g. ANTLR.
I have found one solution by using Regular expression for this question. The answer is as follows
public class Test{
public static void main(String[] args){
String str = " TestProgram";
Pattern pattern = Pattern.compile("\\s*[a-zA-Z0-9]+$");
Matcher matcher = pattern.matcher(str);
while(matcher.find()){
System.out.println(0,matcher.end());
}
}
}
Thanks
Related
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I tried the following regex:
sentences = sb.toString().split("(?<=[a-z])*\\.\\s*");
I am using a stringBuilder sb and converting it to string and then using a split function
The regex checks for 0 or more characters before '.' and 0 or more spaces after the '.'
However, it doesn't work for the following input
Hello World. Shipped to U.S on Friday.We are here .Good input
But I need to keep the space before We are here
Req Output
Hello World
Shipped to U.S on Friday
We are here
Good input
use this regex: ([^\.]+)(\.|$)*?
you can read about group matchers and see the full matches here : https://regex101.com/r/yV9GES/5
edit: updated the link for answer in the comment.
Split your string using \\. i.e. on .
Demo:
import java.util.Arrays;
public class Main {
public static void main(String[] args) {
System.out.println(Arrays.toString("Hello World. We are here .Good input.".split("\\.")));
}
}
Output:
[Hello World, We are here , Good input]
Why do you have to use a RegEx?
You can simply use indexOf and substring
public List<String> splitOnDot(String input) {
List<String> result = new ArrayList<>();
int idx;
while ((idx = input.indexOf('.')) != -1) {
result.add(input.substring(0, idx));
input = input.substring(idx + 1);
}
return result;
}
Successful test:
#Test
public void test1() {
assertThat(splitOnDot("Hello World. We are here .Good input.")).contains("Hello World", " We are here ", "Good input");
}
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For example I have this string, where email addresses are differently formatted:
"a.b#c.d" <a.b#c.d>|"Michal pichal (michal.pichal#g.d)" <michal.pichal#g.d>|Melisko Pan <melisko.pan#domena.sk>
I need to extract the email addresses in a form of:
a.b#c.d|michal.pichal#g.d|melisko.pan#domena.sk
My idea was to get any char near # from group [0-9][A-Z][a-z]#.- but I do not know how. Please help with some hint.
This regex extracts emails out of your string:
public static void main(String[] args) {
Pattern pattern = Pattern.compile("[\\w.]+#[\\w.]+");
Matcher matcher = pattern.matcher("\"a.b#c.d\" <a.b#c.d>|\"Michal pichal (michal.pichal#g.d)\" <michal.pichal#g.d>|Melisko Pan <melisko.pan#domena.sk>\r\n");
while(matcher.find()){
String group = matcher.group();
System.out.println("group="+group);
}
It prints:
group=a.b#c.d
group=a.b#c.d
group=michal.pichal#g.d
group=michal.pichal#g.d
group=melisko.pan#domena.sk
import java.util.Scanner;
class test{
public static void main(String args[]){
Scanner sc = new Scanner(System.in);
String str = sc.nextLine();
String res = ""; //This holds the final result
for(int i=0; i<str.length(); ++i){ //Loop through the entire string
if(str.charAt(i)=='<'){
String build = "";
for(int j=i+1; j<str.length(); ++j){
if(str.charAt(j)=='>'){
break; //Break when we hit the '>'
}
build += str.charAt(j); //Add those between < and >
}
res += build + "|"; //Add the pipe at the end
}
continue;
}
System.out.println(res);
}
}
This ought to do it.
Just run simple nested loops. No need for regex.
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I have a String with some text, f.e.
"Thisisalongwordtest and I want tocutthelongword in pieces"
Now I want to cut the to longs word in 2 pieces with a blank. The word should be cut if it's longer than 10 characters.
The result should be:
"Thisisalon gwordtest and I want tocutthelo ngword in pieces"
How can I achieve this efficiently?
are you looking for this? or I misunderstood the question?
String newString = oldStr.replaceAll("\\w{10}","$0 "))
with your example, the newString is:
Thisisalon gwordtest and I want tocutthelo ngword in pieces
Edit for Pshemo's good comment
to avoid to add space after words with exact 10 chars:
str.replaceAll("\\w{10}(?=\\w)","$0 "));
.replaceAll("(\\w{10})(?=\\w)", "$1 ")
Tested with:
test("abcde fghij klmno pqrst");
test("abcdefghijklmnopqrst");
test("abcdefghijklmnopqrstuv");
test("abcdefghij klmnopqrstuv");
test("abcdefghij klmnopqrst uv");
separate text into words. (by space)
cut long words and replace source word with new words
assemble text again
Note, that this approach will kill multiple-spaces.
(?=\w{10,}\s)(\w{10})
Should be replaced by
"\1 "
you can use replace function.
If it has number or special characters
(?=\S{10,}\s)(\S{10})
can be used.
This is the code i wrote check it once.....
public class TakingInput {
public static void main(String[] args) {
String s="Thisisalongwordtest and I want tocutthelongword in pieces";
StringBuffer sb;
String arr[]=s.split(" ");
for(int i=0;i<arr.length;i++){
if(arr[i].length()>10){
sb=new StringBuffer(arr[i]);
sb.insert(10," ");
arr[i]=new String(sb);
}
}
for(String ss: arr){
System.out.println(ss);//o/p: "Thisisalon gwordtest and I want tocutthelo ngword in pieces"
}
}
}
This code will do exactly what you want.
First create a method that splits a String if its longer than 10 chars:
String splitIfLong(String s){
if(s.length() < 11) return s + " ";
else{
String result = "";
String temp = "";
for(int i = 0; i < s.length(); i++){
temp += s.charAt(i);
if(i == 9)
temp += " ";
result += temp;
temp = "";
}
return result + " ";
}
}
Then use Scanner to read every word in the sentence seperated by a white space" ":
String s = "Thisisalongwordtest and I want tocutthelongword in pieces";
String afterSplit = "";
Scanner in = new Scanner(s);
Then call the splitIfLong() method for every word in the sentence. And add what the method returns to a new String:
while(in.hasNext())
afterSplit += splitIfLong(in.next());
Now you can use the new String as you wish. If you call:
System.out.println(afterSplit);
it will print:
Thisisalon gwordtest and I want tocutthelo ngword in pieces
Hope this helps
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Sorry if my question is silly but I need some help.
Well, the problem is that I am trying to learn java and was trying to make a little program
that will search through the text file for a matching string that has been inserted in the
parameter. I wanted to know which part of the program should I fix to make the method work properly or at least want to know if there is a better solution.
public String linaerSearch(String filename,String strToArrays){
String[]arrays;
File f = new File("C:\\Users\\toyman\\Documents\\NetBeansProjects\\ToyMaker\\"+filename);
String[]items = (strToArrays.split("\\s*,\\s*"));//converting the string into arrays by comma
//convert the int into string
StringBuilder build = new StringBuilder();
if(f.exists()){ //checks if the file actually exists
try(FileInputStream fis = new FileInputStream(f)){
int con; int incrementor =0;
while((con=fis.read())!=-1){
incrementor++;
char str = (char)con;
String str2 = Character.toString(str);
if(items[ ????? ].equals(str2)){
// I want to check if the string that has been passed in the parameter
// exists in the file. But I got confused at the items[ ???? ].
System.out.println("found you");
}
//System.out.println();
//convert to char and display it
System.out.print(str2);
}
}catch(Exception e){
e.printStackTrace();
}
}else{
System.out.println("The file doesn't exist. Create a new file or use a existing file");
}
return "";
}
If you want to search for some string in a text, and do it properly, it has nothing to do with Java. What you're looking for is a string searching algorithm.
Try looking in Wikipedia: http://en.wikipedia.org/wiki/String_searching_algorithm
I'd suggest going for either:
Rabin–Karp algorithm: http://en.wikipedia.org/wiki/Rabin%E2%80%93Karp_string_search_algorithm
Knuth–Morris–Pratt algorithm: http://en.wikipedia.org/wiki/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm
They are both really good and efficient algorithms, and both are fairly easy to implement.
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I am currently trying to work with a custom text file to read quests for a small game, however i am having trouble getting the code to read each character, I've done my research and somehow come up with nothing. I am unsure of how to read a .txt file character by character, so if anyone can help or point me in the right direction it would be strongly appreciated.
Path path = Paths.get("filename");
try (Scanner scanner = new Scanner(path, ENCODING.name())){
while (scanner.hasNextLine()){
String s = scanner.nextLine();
for(char c : s.toCharArray()) {
// your code
}
} catch(IOException e) {/* Reading files can sometimes result in IOException */}
If you want to read each character from file you could do something like this:
BufferedReader r=new BufferedReader(new FileReader("file.txt"));
int ch;
while((ch=r.read())!=-1){
// ch is each character in your file.
}
Good luck
File file = new File("text.txt");
Scanner in = new Scanner(file);
// option 1
while(in.hasNext())
{
String temp = in.next();
char[] temparr = temp.toCharArray();
for(Character j: temparr)
{
//do someting....
}
}
// or option 2
in.useDelimiter("");
while(in.hasNext())
{
temp = in.next();
//do something
}
Option 1 gives you the ability to manipulate the string char by char if the condition is true.
Option just reads one char at a time and lets you preform an action but not manipulate the string found in the text file.
public void method() throws FileNotFoundException
if you dont want to use a try catch