Split String - Cartesian

Question

Given the following line:

"foo bar-baz-zzz"

I want to break it into characters "and" - ", keeping their meaning, but I get all combinations of inputs.

I want to get a two-dimensional array containing

{{"foo", "bar", "baz", "zzz"}
,{"foo bar", "baz", "zzz"}
,{"foo", "bar-baz", "zzz"}
,{"foo bar-baz", "zzz"}
,{"foo", "bar", "baz-zzz"}
,{"foo bar", "baz-zzz"}
,{"foo", "bar-baz-zzz"}
,{"foo bar-baz-zzz"}}

Is there a built-in method in Java to split a string this way? Maybe in a library like Apache? Or do I need to write a for-loops wall?

Answer 1

Here is the recursive solution in which it works . I used List<List<String>>instead of a 2-dimensional array to simplify the task. The code is a little ugly and probably can be a bit tidy.

Output Example:

$ java Main foo bar-baz-zzz
Processing: foo bar-baz-zzz
[foo, bar, baz, zzz]
[foo, bar, baz-zzz]
[foo, bar-baz, zzz]
[foo, bar-baz-zzz]
[foo bar, baz, zzz]
[foo bar, baz-zzz]
[foo bar-baz, zzz]
[foo bar-baz-zzz]

code:

import java.util.*;

public class Main {
  public static void main(String[] args) {
    // First build a single string from the command line args.
    StringBuilder sb = new StringBuilder();
    Iterator<String> it = Arrays.asList(args).iterator();
    while (it.hasNext()) {
      sb.append(it.next());

      if (it.hasNext()) {
        sb.append(' ');
      }
    }

    process(sb.toString());
  }

  protected static void process(String str) {
    System.err.println("Processing: " + str);
    List<List<String>> results = new LinkedList<List<String>>();

    // Invoke the recursive method that does the magic.
    process(str, 0, results, new LinkedList<String>(), new StringBuilder());

    for (List<String> result : results) {
      System.err.println(result);
    }
  }

  protected static void process(String str, int pos, List<List<String>> resultsSoFar, List<String> currentResult, StringBuilder sb) {
    if (pos == str.length()) {
      // Base case: Reached end of string so add buffer contents to current result
      // and add current result to resultsSoFar.
      currentResult.add(sb.toString());
      resultsSoFar.add(currentResult);
    } else {
      // Step case: Inspect character at pos and then make recursive call.
      char c = str.charAt(pos);

      if (c == ' ' || c == '-') {
        // When we encounter a ' ' or '-' we recurse twice; once where we treat
        // the character as a delimiter and once where we treat it as a 'normal'
        // character.
        List<String> copy = new LinkedList<String>(currentResult);
        copy.add(sb.toString());
        process(str, pos + 1, resultsSoFar, copy, new StringBuilder());

        sb.append(c);
        process(str, pos + 1, resultsSoFar, currentResult, sb);
      } else {
        sb.append(c);
        process(str, pos + 1, resultsSoFar, currentResult, sb);
      }
    }
  }
}

Answer 2

, . , Python. , ; , - Java.

def rec(h,t):
  if len(t)<2: return [[h+t]]
  if (t[0]!=' ' and t[0]!='-'): return rec(h+t[0], t[1:])
  return rec(h+t[0], t[1:]) + [ [h]+x for x in rec('',t[1:])]

:

>>> rec('',"foo bar-baz-zzz")
[['foo bar-baz-zzz'], ['foo bar-baz', 'zzz'], ['foo bar', 'baz-zzz'], ['foo bar'
, 'baz', 'zzz'], ['foo', 'bar-baz-zzz'], ['foo', 'bar-baz', 'zzz'], ['foo', 'bar
', 'baz-zzz'], ['foo', 'bar', 'baz', 'zzz']]

Answer 3

, split:

public class Split implements Iterator<List<String>> {
  private Split kid;                 private final Pattern pattern;
  private String subsequence;        private final Matcher matcher;
  private boolean done = false;      private final String sequence;
  public Split(Pattern pattern, String sequence) {
    this.pattern = pattern;          matcher = pattern.matcher(sequence);
    this.sequence = sequence;
  }

  @Override public List<String> next() {
    if (done) { throw new IllegalStateException(); }
    while (true) {
      if (kid == null) {
        if (matcher.find()) {
          subsequence = sequence.substring(matcher.end());
          kid = new Split(pattern, sequence.substring(0, matcher.start()));
        } else { break; }
      } else {
        if (kid.hasNext()) {
          List<String> next = kid.next();
          next.add(subsequence);
          return next;
        } else { kid = null; }
      }
    }
    done = true;
    List<String> list = new ArrayList<String>();
    list.add(sequence);
    return list;
  }
  @Override public boolean hasNext() { return !done; }
  @Override public void remove() { throw new UnsupportedOperationException(); }
}

( - ).

:

Pattern pattern = Pattern.compile(" |-");
String str = "foo bar-baz-zzz";
Split split = new Split(pattern, str);
while (split.hasNext()) {
  System.out.println(split.next());
}

... :

[foo, bar-baz-zzz]
[foo, bar, baz-zzz]
[foo bar, baz-zzz]
[foo, bar-baz, zzz]
[foo, bar, baz, zzz]
[foo bar, baz, zzz]
[foo bar-baz, zzz]
[foo bar-baz-zzz]

, .

Answer 4

?

, N N * 2 ^ N. () , ...

, , , , ? , - , , . .

Answer 5

.

( "-" ), , , , , .

In your case, you have 3 delimiters: "", "-" and "-", so you have 3 binary flags. In the line you will get 2 ^ 3 = 8 values.