Trim a string in java to get first word

You could use String's replaceAll() method which takes a regular expression as input, to replace everything after the space including the space, if a space does indeed exist, with the empty string:

String firstWord = sentence.replaceAll(" .*", "");

  String firstWord = "Magic Word";
     if(firstWord.contains(" ")){
        firstWord= firstWord.substring(0, firstWord.indexOf(" ")); 
        System.out.println(firstWord);
     }