Java Program to Highlight Syntax - Industry Standard Code

Problem Statement: 
We need to highlight words in a sentence that matches a given list of keywords. Matched words should be surrounded by "[blue]".

Sample Input:
If my code contains many for loops or while loops then my program may run slow. 

Keywords List:
if, else, then, until, while, do , for

Sample Output:
[blue]If[blue] my code contains many [blue]for[blue] loops or [blue]while[blue] loops [blue]then[blue] my program may run slow.

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Solution: 

• SyntaxHighlighter.java

package com.hellojavatech.syntaxhighlight;

import java.util.ArrayList;
import java.util.Scanner;

/**
 * 
 * @author Sagar
 * Class to highlight words that matches keyword list
 *
 */
public class SyntaxHighlighter {

public static void main(String[] args) {

UIForInputAndDisplay uiForInputAndDisplay = new UIForInputAndDisplay();
String userInput = uiForInputAndDisplay.getInputText();

KeywordsList keywordsList = new KeywordsList();
ArrayList keywords = keywordsList.keywordsToHighlight();

ProcessText processText = new ProcessText();
String highlightedString = processText.processInput(keywords, userInput);

uiForInputAndDisplay.displayHighlightedText(highlightedString);
}

}

• UIForInputAndDisplay.java

package com.hellojavatech.syntaxhighlight;

import java.util.Scanner;

public class UIForInputAndDisplay {

/**
* method to get Input from user
* @return String userInput
*/
public String getInputText() {

Scanner sc = new Scanner(System.in);
System.out.println("Enter a Sentence: ");
String userInput = sc.nextLine();
return userInput;
}

/**
* method to display highlighted String
* @param highlightedString
*/
public void displayHighlightedText(String highlightedString) {

System.out.println("Text after Syntax Highlighting is: ");
System.out.println(highlightedString);
}

}

• keywordsToHighlight.java

package com.hellojavatech.syntaxhighlight;

import java.util.ArrayList;

public class KeywordsList {

/**

* method to create list of keywords

* @return ArrayList list of keywords

*/

public ArrayList keywordsToHighlight() {

ArrayList keywords = new ArrayList();

keywords.add("if");

keywords.add("else");

keywords.add("then");

keywords.add("until");

keywords.add("while");

keywords.add("do");

keywords.add("for");

return keywords;

}

}

• processInput.java

package com.hellojavatech.syntaxhighlight;

import java.util.ArrayList;

import java.util.Scanner;

public class ProcessText {

/**

* method to process the user input to highlight keywords

* @param keywords

* @param userInput

* @return String processed text

*/

public String processInput(ArrayList keywords, String userInput) {

StringBuilder tempString = new StringBuilder(); 

String[] splitInput = userInput.split(" ");

for (String word : splitInput) {

if(keywords.contains(word)){

tempString.append("[blue]"+word+"[blue]");

}

else{

tempString.append(word);

}

tempString.append(" ");

}

return tempString.toString().trim();

}

}

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