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Java Regex to find in a Text all the possible pairs of a list

I have a List of Strings containing names and surnames and i have a free text.
List<String> names; // contains: "jon", "snow", "arya", "stark", ...
String text = "jon snow and stark arya";
I have to find all the names and surnames, possibly with a Java Regex (so using Pattern and Matcher objects). So i want something like:
List<String> foundNames; // contains: "jon snow", "stark arya"
I have done this 2 possible ways but without using Regex, they are not static beacause part of a NameFinder class that have a list "names" that contains all the names.
public List<String> findNamePairs(String text) {
List<String> foundNamePairs = new ArrayList<String>();
List<String> names = this.names;
text = text.toLowerCase();
for (String name : names) {
String nameToSearch = name + " ";
int index = text.indexOf(nameToSearch);
if (index != -1) {
String textSubstring = text.substring(index + nameToSearch.length());
for (String nameInner : names) {
if (name != nameInner && textSubstring.startsWith(nameInner)) {
foundNamePairs.add(name + " " + nameInner);
}
}
}
}
removeDuplicateFromList(foundNamePairs);
return foundNamePairs;
}
or in a worse (very bad) way (creating all the possible pairs):
public List<String> findNamePairsInTextNotOpt(String text) {
List<String> foundNamePairs = new ArrayList<String>();
text = text.toLowerCase();
List<String> pairs = getNamePairs(this.names);
for (String name : pairs) {
if (text.contains(name)) {
foundNamePairs.add(name);
}
}
removeDuplicateFromList(foundNamePairs);
return foundNamePairs;
}

You can create a regex using the list of names and then use find to find the names. To ensure you don't have duplicates, you can check if the name is already in the list of found names. The code would look like this.
List<String> names = Arrays.asList("jon", "snow", "stark", "arya");
String text = "jon snow and Stark arya and again Jon Snow";
StringBuilder regexBuilder = new StringBuilder();
for (int i = 0; i < names.size(); i += 2) {
regexBuilder.append("(")
.append(names.get(i))
.append(" ")
.append(names.get(i + 1))
.append(")");
if (i != names.size() - 2) regexBuilder.append("|");
}
System.out.println(regexBuilder.toString());
Pattern compile = Pattern.compile(regexBuilder.toString(), Pattern.CASE_INSENSITIVE);
Matcher matcher = compile.matcher(text);
List<String> found = new ArrayList<>();
int start = 0;
while (matcher.find(start)) {
String match = matcher.group().toLowerCase();
if (!found.contains(match)) found.add(match);
start = matcher.end();
}
for (String s : found) System.out.println("found: " + s);
If you want to be case sensitive just remove the flag in Pattern.compile(). If all matches have the same capitalization you can omit the toLowerCase() in the while loop as well.
But make sure that the list contains a multiple of 2 as list elements (name and surname) as the for-loop will throw an IndexOutOfBoundsException otherwise. Also the order matters in my code. It will only find the name pairs in the order they occur in the list. If you want to have both orders, you can change the regex generation accordingly.
Edit: As it is unknown whether a name is a surname or name and which build a name/surname pair, the regex generation must be done differently.
StringBuilder regexBuilder = new StringBuilder("(");
for (int i = 0; i < names.size(); i++) {
regexBuilder.append("(")
.append(names.get(i))
.append(")");
if (i != names.size() - 1) regexBuilder.append("|");
}
regexBuilder.append(") ");
regexBuilder.append(regexBuilder);
regexBuilder.setLength(regexBuilder.length() - 1);
System.out.println(regexBuilder.toString());
This regex will match any of the given names followed by a space and then again any of the names.

Java help needed for a code like Autocorrect

I am writing a program which is the opposite of Auto Correct. The logic is that the user enters a sentence, when a button is pressed, the grammatical opposite of the sentence entered by the user should be displayed. I am roughly able to get the code. I used the matcher logic.But i am not able to get the desired output. I am linking the code with this question. Can anyone help me please?
imageButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String input = editText.getText().toString();
String store = input;
String store1 [] = store.split(" ");
String correct[] = {"is","shall","this","can","will"};
String wrong [] = {"was","should","that","could","would"};
String output = "";
for (int i=0;i<store1.length;i++) {
for(int j=0;j<correct.length;j++){
if(store1[i].matches(correct[j])) {
output = input.replace(store1[i], wrong[j]);
//store1[i] = wrong[j];
}
else
{
input.replace(store1[i], store1[i]);
//store1[i] = store1[i];
}
}
mTextView.setText(output);
}
}});

By looking at your code, I've found some redundancy and unused variable. Shown as below.
String store = input;
String store1 [] = store.split(" ");
As shown below, I did some cleanup for you and implement your logic using Map interface. The wrong value must be the Key of the map so that we can easily determine is the word a wrong value using Map.containKeys(word). If key is found then we concatenate the output variable with the correct word.
String input = editText.getText().toString().split(" ");
Map<String, String> pairs = new HashMap<>();
pairs.put("is", "was");
pairs.put("shall", "should");
pairs.put("this", "that");
pairs.put("can", "could");
pairs.put("will", "would");
String output = "";
for (String word : input) {
if (pairs.containsKey(word)) {
output = output + pairs.get(word) + " ";
} else {
output = output + word + " ";
}
}
mTextView.setText(output.trim());

How do sort my pattern match results as complete match, half a match and so on [duplicate]

This question already has an answer here:
Closed 10 years ago.
Possible Duplicate:
Regular expression not matching subwords in phrase
My program displays the matching results, but I want to sort the results as complete match (100%), half a match and so on.
My text file contains the following line:
Red car
Red
Car
So If I search for: “red car”. I get the following results
Red car
Red
Car
So what I want to do is to sort the found results as follows:
"red car" 100% match
"red" 40% match
"car" 40% match
Any help is appreciated.
Any help is appreciated. My code is as follows:
public static void main(String[] args) {
// TODO code application logic here
String strLine;
try{
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream("C:\\textfile.txt"");
// Get the object of DataInputStream
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
Scanner input = new Scanner (System.in);
System.out.print("Enter Your Search: "); // String key="red or yellow";
String key = input.nextLine();
while ((strLine = br.readLine()) != null) {
Pattern p = Pattern.compile(key); // regex pattern to search for
Matcher m = p.matcher(strLine); // src of text to search
boolean b = false;
while(b = m.find()) {
System.out.println( " " + m.group()); // returns index and match
// Print the content on the console
}
}
//Close the input stream
in.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}

Assuming you are searching for "Red" or "Yellow", and or is the only logical operator you need (no 'and' or 'xor') and you don't want to use any wildcards or regular-expressions in what you search for, then I would simply loop through, trying to match each String in turn against the line. In pseudo-code, something like:
foreach (thisLine: allLinesInTheFile) {
numOfCharsMatching = 0
foreach (thisString: allSearchStrings) {
if (thisLine.contains(thisString) {
numOfCharsMatching = numOfCharsMatching + thisString.length
}
}
score = ( numOfCharsMatching / thisLine.length ) * 100
}
If you don't want spaces to count in your score, then you'd need to remove them from the thisString.length (and not allow them in your search terms)
One other problem is the numOfCharsMatching will be incorrect if matches can overlap (i.e. if searching for 'row' or 'brown' in 'brown row' it will say that there are 11 characters matching, longer than the length of the string. You could use a BitSet to track which characters have been involved in a match, something like:
foreach (thisLine: allLinesInTheFile) {
whichCharsMatch = new BitSet()
foreach (thisString: allSearchStrings) {
if (thisLine.contains(thisString) {
whichCharsMatch.set(startPositionOfMatch, endPositionOfMatch, true)
}
}
score = ( numOfCharsMatching / thisLine.length ) * 100
}
Have a look at the BitSet javadoc, particularly the set and cardinality methods

How can you parse the string which has a text qualifier

How can I parse a String str = "abc, \"def,ghi\"";
such that I get the output as
String[] strs = {"abc", "\"def,ghi\""}
i.e. an array of length 2.
Should I use regular expression or Is there any method in java api or anyother opensource
project which let me do this?
Edited
To give context about the problem, I am reading a text file which has a list of records one on each line. Each record has list of fields separated by delimiter(comma or semi-colon). Now I have a requirement where I have to support text qualifier some thing excel or open office supports. Suppose I have record
abc, "def,ghi"
In this , is my delimiter and " is my text qualifier such that when I parse this string I should get two fields abc and def,ghi not {abc,def,ghi}
Hope this clears my requirement.
Thanks
Shekhar

The basic algorithm is not too complicated:
public static List<String> customSplit(String input) {
List<String> elements = new ArrayList<String>();
StringBuilder elementBuilder = new StringBuilder();
boolean isQuoted = false;
for (char c : input.toCharArray()) {
if (c == '\"') {
isQuoted = !isQuoted;
// continue; // changed according to the OP comment - \" shall not be skipped
}
if (c == ',' && !isQuoted) {
elements.add(elementBuilder.toString().trim());
elementBuilder = new StringBuilder();
continue;
}
elementBuilder.append(c);
}
elements.add(elementBuilder.toString().trim());
return elements;
}

This question seems appropriate: Split a string ignoring quoted sections
Along that line, http://opencsv.sourceforge.net/ seems appropriate.

Try this -
String str = "abc, \"def,ghi\"";
String regex = "([,]) | (^[\"\\w*,\\w*\"])";
for(String s : str.split(regex)){
System.out.println(s);
}

Try:
List<String> res = new LinkedList<String>();
String[] chunks = str.split("\\\"");
if (chunks.length % 2 == 0) {
// Mismatched escaped quotes!
}
for (int i = 0; i < chunks.length; i++) {
if (i % 2 == 1) {
res.addAll(Array.asList(chunks[i].split(",")));
} else {
res.add(chunks[i]);
}
}
This will only split up the portions that are not between escaped quotes.
Call trim() if you want to get rid of the whitespace.

Tokenize a string with a space in java

I want to tokenize a string like this
String line = "a=b c='123 456' d=777 e='uij yyy'";
I cannot split based like this
String [] words = line.split(" ");
Any idea how can I split so that I get tokens like
a=b
c='123 456'
d=777
e='uij yyy';

The simplest way to do this is by hand implementing a simple finite state machine. In other words, process the string a character at a time:
When you hit a space, break off a token;
When you hit a quote keep getting characters until you hit another quote.

Depending on the formatting of your original string, you should be able to use a regular expression as a parameter to the java "split" method: Click here for an example.
The example doesn't use the regular expression that you would need for this task though.
You can also use this SO thread as a guideline (although it's in PHP) which does something very close to what you need. Manipulating that slightly might do the trick (although having quotes be part of the output or not may cause some issues). Keep in mind that regex is very similar in most languages.
Edit: going too much further into this type of task may be ahead of the capabilities of regex, so you may need to create a simple parser.

line.split(" (?=[a-z+]=)")
correctly gives:
a=b
c='123 456'
d=777
e='uij yyy'
Make sure you adapt the [a-z+] part in case your keys structure changes.
Edit: this solution can fail miserably if there is a "=" character in the value part of the pair.

StreamTokenizer can help, although it is easiest to set up to break on '=', as it will always break at the start of a quoted string:
String s = "Ta=b c='123 456' d=777 e='uij yyy'";
StreamTokenizer st = new StreamTokenizer(new StringReader(s));
st.ordinaryChars('0', '9');
st.wordChars('0', '9');
while (st.nextToken() != StreamTokenizer.TT_EOF) {
switch (st.ttype) {
case StreamTokenizer.TT_NUMBER:
System.out.println(st.nval);
break;
case StreamTokenizer.TT_WORD:
System.out.println(st.sval);
break;
case '=':
System.out.println("=");
break;
default:
System.out.println(st.sval);
}
}
outputs
Ta
=
b
c
=
123 456
d
=
777
e
=
uij yyy
If you leave out the two lines that convert numeric characters to alpha, then you get d=777.0, which might be useful to you.

Assumptions:
Your variable name ('a' in the assignment 'a=b') can be of length 1 or more
Your variable name ('a' in the assignment 'a=b') can not contain the space character, anything else is fine.
Validation of your input is not required (input assumed to be in valid a=b format)
This works fine for me.
Input:
a=b abc='123 456' &=777 #='uij yyy' ABC='slk slk' 123sdkljhSDFjflsakd#*#&=456sldSLKD)#(
Output:
a=b
abc='123 456'
&=777
#='uij yyy'
ABC='slk slk'
123sdkljhSDFjflsakd#*#&=456sldSLKD)#(
Code:
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexTest {
// SPACE CHARACTER followed by
// sequence of non-space characters of 1 or more followed by
// first occuring EQUALS CHARACTER
final static String regex = " [^ ]+?=";
// static pattern defined outside so that you don't have to compile it
// for each method call
static final Pattern p = Pattern.compile(regex);
public static List<String> tokenize(String input, Pattern p){
input = input.trim(); // this is important for "last token case"
// see end of method
Matcher m = p.matcher(input);
ArrayList<String> tokens = new ArrayList<String>();
int beginIndex=0;
while(m.find()){
int endIndex = m.start();
tokens.add(input.substring(beginIndex, endIndex));
beginIndex = endIndex+1;
}
// LAST TOKEN CASE
//add last token
tokens.add(input.substring(beginIndex));
return tokens;
}
private static void println(List<String> tokens) {
for(String token:tokens){
System.out.println(token);
}
}
public static void main(String args[]){
String test = "a=b " +
"abc='123 456' " +
"&=777 " +
"#='uij yyy' " +
"ABC='slk slk' " +
"123sdkljhSDFjflsakd#*#&=456sldSLKD)#(";
List<String> tokens = RegexTest.tokenize(test, p);
println(tokens);
}
}

Or, with a regex for tokenizing, and a little state machine that just adds the key/val to a map:
String line = "a = b c='123 456' d=777 e = 'uij yyy'";
Map<String,String> keyval = new HashMap<String,String>();
String state = "key";
Matcher m = Pattern.compile("(=|'[^']*?'|[^\\s=]+)").matcher(line);
String key = null;
while (m.find()) {
String found = m.group();
if (state.equals("key")) {
if (found.equals("=") || found.startsWith("'"))
{ System.err.println ("ERROR"); }
else { key = found; state = "equals"; }
} else if (state.equals("equals")) {
if (! found.equals("=")) { System.err.println ("ERROR"); }
else { state = "value"; }
} else if (state.equals("value")) {
if (key == null) { System.err.println ("ERROR"); }
else {
if (found.startsWith("'"))
found = found.substring(1,found.length()-1);
keyval.put (key, found);
key = null;
state = "key";
}
}
}
if (! state.equals("key")) { System.err.println ("ERROR"); }
System.out.println ("map: " + keyval);
prints out
map: {d=777, e=uij yyy, c=123 456, a=b}
It does some basic error checking, and takes the quotes off the values.

This solution is both general and compact (it is effectively the regex version of cletus' answer):
String line = "a=b c='123 456' d=777 e='uij yyy'";
Matcher m = Pattern.compile("('[^']*?'|\\S)+").matcher(line);
while (m.find()) {
System.out.println(m.group()); // or whatever you want to do
}
In other words, find all runs of characters that are combinations of quoted strings or non-space characters; nested quotes are not supported (there is no escape character).

public static void main(String[] args) {
String token;
String value="";
HashMap<String, String> attributes = new HashMap<String, String>();
String line = "a=b c='123 456' d=777 e='uij yyy'";
StringTokenizer tokenizer = new StringTokenizer(line," ");
while(tokenizer.hasMoreTokens()){
token = tokenizer.nextToken();
value = token.contains("'") ? value + " " + token : token ;
if(!value.contains("'") || value.endsWith("'")) {
//Split the strings and get variables into hashmap
attributes.put(value.split("=")[0].trim(),value.split("=")[1]);
value ="";
}
}
System.out.println(attributes);
}
output:
{d=777, a=b, e='uij yyy', c='123 456'}
In this case continuous space will be truncated to single space in the value.
here attributed hashmap contains the values

import java.io.*;
import java.util.Scanner;
public class ScanXan {
public static void main(String[] args) throws IOException {
Scanner s = null;
try {
s = new Scanner(new BufferedReader(new FileReader("<file name>")));
while (s.hasNext()) {
System.out.println(s.next());
<write for output file>
}
} finally {
if (s != null) {
s.close();
}
}
}
}

java.util.StringTokenizer tokenizer = new java.util.StringTokenizer(line, " ");
while (tokenizer.hasMoreTokens()) {
String token = tokenizer.nextToken();
int index = token.indexOf('=');
String key = token.substring(0, index);
String value = token.substring(index + 1);
}

Have you tried splitting by '=' and creating a token out of each pair of the resulting array?