Given a string, I need to print out all permutations of the string. How should I do that? I have tried
for(int i = 0; i<word.length();i++) { for(int j='a';j<='z';j++){ word = word.charAt(i)+""+(char)j; System.out.println(word); } } Is there a good way about doing this?
I'm not 100% sure that I understand what you are trying to do. I'm going to go by your original wording of the question and your comment to @ErstwhileIII's answer, which make me think that it's not really "permutations" (i.e. rearrangement of the letters in the word) that you are looking for, but rather possible single-letter modifications (not sure what a better word for this would be either), like this:
Take a word like "hello" and print a list of all "versions" you can get by adding one "typo" to it:
hello -> aello, bello, cello, ..., zello, hallo, hbllo, hcllo, ..., hzllo, healo, heblo, ...
If that's indeed what you're looking for, the following code will do that for you pretty efficiently:
public void process(String word) { // Convert word to array of letters char[] letters = word.toCharArray(); // Run through all positions in the word for (int pos=0; pos<letters.length; pos++) { // Run through all letters for the current position for (char letter='a'; letter<='z'; letter++) { // Replace the letter letters[pos] = letter; // Re-create a string and print it out System.out.println(new String(letters)); } // Set the current letter back to what it was letters[pos] = word.charAt(pos); } } OH .. to print out all permutations of a string, consider your algorithm first. What is the definition of "all permutations" .. for example:
Reflect on the algorithm you would use (write it down in english) .. then translate to Java code
While not the most efficient, a recursive solution might be easiest to use (i.e. for a string of length n, go through each of the characters and follow that with the permutations of the string with that character removed).
EDIT: Ok... you changed your request. Permutations is a whole other story. I think this will help: Generating all permutations of a given string
Not sure what you are trying to do... Example 1 is to get the alphabet one letter next to another. Example 2 is to print whatever you gave us there as an example.
//Example 1 String word=""; //empty string for(int i = 65; i<=90;i++){ //65-90 are the Ascii numbers for capital letters word+=(char)i; //cast int to char } System.out.println(word); //Example 2 String word=""; for (int i=65;i<=90;i++){ word+=(char)i+"rse"; if(i!=90){ //you don't want this at the end of your sentence i suppose :) word+=", "; } } System.out.println(word); 
