String Info

Gives information about a string.

Files: StringInfo.java
Areas: General

1import java.io.*;
2
3public class StringInfo {
/**
 * Return the number of 'a's plus the number of 'b's in s.
 * Precondition: s != null.
 */
public static int numAsAndBs(String s) {
  int count= 0;
  for(int i= 0; i < s.length(); i++) {
    if(s.charAt(i) == 'a' || s.charAt(i) == 'b') {
      count++;
    }
  }
  return count;
}
17
18
/**
 * A run is a sequence of the same character. Return the letter
 * that has the longest run in s. For example, in "aaabbbbccaa",
 * 'b' would be the result, since it occurs 4 times in a row.
 * Precondition: s != null && s.length() > 0.
 */
public static char longestRun(String s) {
  char longest= s.charAt(0);
  char tempLongest= s.charAt(0);
  int count= 1;
  int tempCount= 1;
30
  for(int i= 1; i < s.length(); i++) {
    if(s.charAt(i) == tempLongest) {
      tempCount++;
    } else {
      if(tempCount > count) {
        count= tempCount;
        longest= tempLongest;
      }
      tempCount= 1;
      tempLongest= s.charAt(i);
    }
  }
  if(tempCount > count) {
    count= tempCount;
    longest= tempLongest;
  }
47
  return longest;
}
50
51
/**
 * Return whether s contains every letter in t. For example,
 * "abcd" contains all the letters in "bbdc", since every letter
 * in the second String appears in the first.
 * Precondition: s != null && t != null.
 */
public static boolean contains(String s, String t) {
  boolean contains= true;
  for(int i= 0; contains && i < t.length(); i++) {
    contains= contains && (s.indexOf(t.charAt(i)) >= 0);
  }
  return contains;
}
65
66
/**
 * Return whether s contains every letter in t, including duplicate
 * letters. For example, "abcd" does not contain all the letters in
 * "bbdc", since there is only 1 'b' in "abcd".
 * Precondition: s != null && t != null.
 */
public static boolean containsAllOf(String s, String t) {
  boolean containsAll= true;
  for(int i= 0; containsAll && i < t.length(); i++) {
    int loc= s.indexOf(t.charAt(i));
    if (loc >= 0) {
      s= s.substring(0, loc) + s.substring(loc + 1);
    } else {
      containsAll= false;
    }
  }
  return containsAll;
}
85
86
/**
 * Read a series of Strings from file f, and return the longest String,
 * or null if the file is empty.
 * Precondition: f != null.
 */
public static String getLongest(String f) throws IOException {
  BufferedReader br= new BufferedReader(new FileReader(f));
  String longest= null;
  String line= br.readLine();
  while(line != null) {
    if (longest == null || line.length() > longest.length()) {
      longest= line;
    }
    line= br.readLine();
  }
  return longest;
}
104
105
/**
 * Read a series of Strings from file f until one is found that
 * is longer than the sum of the lengths of the previous two, or
 * null if no such Strings are found.
 * Precondition: f != null.
 */
public static String getLongerThanPreviousTwo(String f) throws IOException {
  BufferedReader br= new BufferedReader(new FileReader(f));
114
  /* The result. null until a line meeting the criterion is found or the
   * end of the file is reached.
   */
  String result= null;
119
  String l1= br.readLine(); // the penultimate line.
  String l2= br.readLine(); // the previous line.
122
  String next= br.readLine(); // The next candidate.
  while(next != null && result == null) {
    if (next.length() > l1.length() + l2.length()) {
      result= next;
    }
    l1= l2;
    l2= next;
    next= br.readLine();
  }
  return result;
}
134
135
/**
 * Read a series of Strings from file f, and return (concatenated without
 * newlines) all the Strings that are longer than the sum of the lengths
 * of the two previous to them, or null if no such Strings are found.
 * Precondition: f != null.
 */
public static String getAllLongerThanPreviousTwo(String f) throws IOException {
  BufferedReader br= new BufferedReader(new FileReader(f));
144
  /* The result. null until a line meeting the criterion is found or the
   * end of the file is reached.
   */
  String result= null;
149
  String l1= br.readLine(); // the penultimate line.
  String l2= br.readLine(); // the previous line.
152
  String next= br.readLine(); // The next candidate.
  while(next != null) {
    if (next.length() > l1.length() + l2.length()) {
      if (result == null) {
        result= next;
      } else {
        result += next;
      }
    }
162
    l1= l2;
    l2= next;
    next= br.readLine();
  }
  return result;
}
169
170
171}

		