I want to generate possible tokens using forward traversal in Java. For example if I have a string "This is my car". I need to generate tokens
What is the best way to do this? Any examples? Thanks.
Here is another solution with split and nested loops:
public static void main(String[] args) {
String original = "this is my car";
String[] singleWords = original.split(" "); // split the String to get the single words
ArrayList<String> results = new ArrayList<String>(); // a container for all the possible sentences
for (int startWord = 0; startWord < singleWords.length; startWord++) { // starWords start with 0 and increment just until they reach the last word
for (int lastWord = singleWords.length; lastWord > startWord; lastWord--) { // last words start at the end and decrement just until they reached the first word
String next = "";
for (int i = startWord; i != lastWord; i++) { // put all words in one String (starting with the startWord and ending with the lastWord)
next += singleWords[i] + " ";
}
results.add(next); // add the next result to your result list
}
}
// this is just to check the results. All your sentences are now stored in the ArrayList results
for (String string : results) {
System.out.println("" + string);
}
}
and this was my result when I tested the method:
this is my car
this is my
this is
this
is my car
is my
is
my car
my
car
Use Guava:
String yourOriginalString = "This is my car";
final Set<String> originalWords =
Sets.newLinkedHashSet(
Splitter.on(CharMatcher.WHITESPACE).trimResults().split(yourOriginalString));
final Set<Set<String>> variations = Sets.powerSet(originalWords);
for (Set<String> variation : variations) {
System.out.println(Joiner.on(' ').join(variation));
}
Output:
This
is
This is
my
This my
is my
This is my
car
This car
is car
This is car
my car
This my car
is my car
This is my car
Here is a possible way:
//Just a method that seperates your String into an array of words based on the spaces
//I'll leave that for you to figure out how to make
String[] array = getSeperatedWords(<yourword>);
List<StringBuffer> bufferArray = new ArrayList<StringBuffer>();
for(int i = 0; i < array.length; i++){
StringBuffer nowWord = array[i];
for(int j = i; j < array.length; j++{
nowWord.append(array[j]);
}
bufferArray.add(nowWord);
}
for(int i = 0; i < bufferArray.length; i++){
System.out.print(bufferArray.get(i));
}
j from i to the end of the array?import java.util.Arrays;
public class Test {
public static void main(String[] args) {
String var = "This is my car";
permute(var);
}
public static void permute(String var) {
if(var.isEmpty())
return;
String[] arr = var.split(" ");
while(arr.length > 0) {
for(String str : arr) {
System.out.print(str + " ");
}
arr = (String[]) Arrays.copyOfRange(arr, 0, arr.length - 1);
System.out.println();
}
String[] original = var.split(" ");
permute(implodeArray((String[]) Arrays.copyOfRange(original, 1, original.length), " "));
}
public static String implodeArray(String[] inputArray, String glueString) {
String output = "";
if (inputArray.length > 0) {
StringBuilder sb = new StringBuilder();
sb.append(inputArray[0]);
for (int i=1; i<inputArray.length; i++) {
sb.append(glueString);
sb.append(inputArray[i]);
}
output = sb.toString();
}
return output;
}
}
Read this book, you will be a master on recursion: http://mitpress.mit.edu/sicp/
split(" "), then use a doubly nested loop to generate.