问题
Say I have a string x and I want to add some character x amount of times so that string x becomes of length y, how would I do this?
String x = "this_is_a_line";
//x.length() = 14;
length y = 20;
//insert character into line so String x becomes balanced to:
x = "this___is___a___line";
//x.length() = 20;
Another example:
String y = "in_it_yeah";
//y.length() = 10
length j = 15;
//inserting characters so String y becomes balanced to:
y = "in____it___yeah";
I want to avoid using StringBuilder to append characters.
My thought process:
- Create a Char array of length y.
- Copy the string to array.
- Attempt to shift the characters one by one from the furthest character to the right.
回答1:
I hope I understood you correctly but I think this code does what you're requesting.
Edit: this one will distribute the specified character evenly and can create strings like "a__b_c" if the string isn't long enough yet.
import java.util.ArrayList;
public class Main {
public static void main(String[] args) {
String string = "this_is_a_line";
int length = string.length();
int desiredLength = 16;
int extraLengthRequired = desiredLength - length;
char characterToBeDuplicated = '_';
String[] rawPieces = string.split(Character.toString(characterToBeDuplicated));
ArrayList<String> pieces = new ArrayList<>();
int emptyIndexes = 0;
for (String piece : rawPieces) {
if(piece.equals("")) {
emptyIndexes++;
} else {
pieces.add(piece);
}
}
int numOfCharactersToBeMultiplied = pieces.size() - 1;
int numOfMultiplications = (int) Math.floor((extraLengthRequired + emptyIndexes) / numOfCharactersToBeMultiplied) + 1;
int lengthLeft = (extraLengthRequired + emptyIndexes) % numOfCharactersToBeMultiplied;
String newString = pieces.get(0);
for (int i = 1; i < pieces.size(); i++) {
newString += characterToBeDuplicated;
if(lengthLeft > 0) {
newString += characterToBeDuplicated;
lengthLeft--;
}
for (int j = 1; j < numOfMultiplications; j++) {
newString += characterToBeDuplicated;
}
newString += pieces.get(i);
}
System.out.println(newString + " - " + newString.length());
}
}
Old solution:
public class Main {
public static void main(String[] args) {
String string = "this_is_a_line";
int length = string.length();
int desiredLength = 20;
int extraLengthRequired = desiredLength - length;
char characterToBeDuplicated = '_';
String[] pieces = string.split(Character.toString(characterToBeDuplicated));
int numOfCharactersToBeMultiplied = pieces.length - 1;
int numOfMultiplications = (int) Math.floor(extraLengthRequired / numOfCharactersToBeMultiplied);
String newString = pieces[0];
for (int i = 1; i < pieces.length; i++) {
newString += characterToBeDuplicated;
for (int j = 1; j < numOfMultiplications; j++) {
newString += characterToBeDuplicated;
}
newString += pieces[i];
}
System.out.println(newString);
}
}
回答2:
I did this one because when I started doing a pseudo code it was a bit challenging for me, though I'm not a fan of answering questions like this on "gimme teh codez".
I recommend you though using StringBuilder on String concatenation inside for loops because it's more efficient than actual String concatenation with +=.
Note that:
- This program adds spaces to the end, that's why I print it's length trimmed.
- I split it by space with a regex
\\s+instead of_because that's how you wrote it 1st
The following code works for
a____b_c -> a___b___c (Lenght 9)
a____b_c -> a____b___c (Lenght 10)
this_is_a_line -> this___is___a___line (Lenght 20)
in_it_yeah -> in____it___yeah (Length 15)
Code:
class EnlargeString {
public static void main (String args[]) {
String x = "a b c";
int larger = 10;
int numberOfSpaces = 0;
String s[] = x.split("\\s+"); //We get the number of words
numberOfSpaces = larger - s.length; //The number of spaces to be added after each token
int extraSpaces = numberOfSpaces % s.length; //Extra spaces for the cases of 4 spaces then 3 or something like that
System.out.println(extraSpaces);
String newSpace[] = new String[s.length]; //The String array that will contain all string between words
for (int i = 0; i < s.length; i++) {
newSpace[i] = " "; //Initialize the previous array
}
//Here we add the extra spaces (the cases of 4 and 3)
for (int i = 0; i < s.length; i++) {
if (extraSpaces == 0) {
break;
}
newSpace[i] += " ";
extraSpaces--;
}
for (int i = 0; i < s.length; i++) {
for (int j = 0; j < totalSpaces / s.length; j++) {
newSpace[i] += " "; //Here we add all the equal spaces for all tokens
}
}
String finalWord = "";
for (int i = 0; i < s.length; i++) {
finalWord += (s[i] + newSpace[i]); //Concatenate
}
System.out.println(x);
System.out.println(x.length());
System.out.println(finalWord);
System.out.println(finalWord.trim().length());
}
}
Next time try to do it yourself 1st and show YOUR logic, then your question will be better received (maybe with upvotes instead of downvotes) this is called a Runnable Example. I also recommend you to take a look at String concatenation vs StringBuilder and How to ask a good question, also you might want to Take the tour
回答3:
Here is my solution:
public class Main
{
public static void main(String args[]){
System.out.print("#Enter width : " );
int width = BIO.getInt();
System.out.print("#Enter line of text : " );
String line = BIO.getString().trim();
int nGaps, spToAdd, gapsLeft, modLeft, rem;
nGaps = spToAdd = gapsLeft = rem = 0;
double route = 0;
String sp = " ";
while ( ! line.equals( "END" )){
nGaps = numGaps(line);
if (nGaps == 0) { line = compLine(line, width).replace(" ", "."); }
else if (nGaps == width) { line = line.replace(" ", "."); }
else{
int posArray[] = new int[nGaps];
posArray = pos(line, nGaps);
gapsLeft = width - line.length();
spToAdd = gapsLeft / nGaps;
modLeft = gapsLeft % nGaps;
route = gapsLeft / nGaps;
sp = spGen(spToAdd);
line = reFormat(posArray, line, width, sp, spToAdd);
if (line.length() < width){
System.out.print("#OK\n");
nGaps = numGaps(line);
int posArray2[] = new int[nGaps];
posArray2 = pos(line, nGaps);
line = compFormat(posArray2, line, modLeft);
}
line = line.replace(" ", ".");
}
System.out.println(line);
System.out.println("#Length is: " + line.length());
System.out.print("#Enter line of text : " );
line = BIO.getString().trim();
}
}
public static int numGaps(String oLine){
int numGaps = 0;
for (char c : oLine.toCharArray()) { if (c == ' ') { numGaps++; } }
return numGaps;
}
public static String spGen(int count) {
return new String(new char[count]).replace("\0", " ");
}
public static String compLine(String oLine, int width){
String newLine = oLine;
int pos = oLine.length();
int numOSpace = width - oLine.length();
String sp = spGen(numOSpace);
newLine = new StringBuilder(newLine).insert(pos, sp).toString();
return newLine;
}
public static int[] pos(String oLine, int nGaps){
int posArray[] = new int[nGaps];
int i = 0;
for (int pos = 0; pos < oLine.length(); pos++) {
if (oLine.charAt(pos) == ' ') { posArray[i] = pos; i++; }
}
//for (int y = 0; y < x; ++y) { System.out.println(posArray[y]); }
return posArray;
}
public static String reFormat(int[] posArray, String oLine, int width, String sp, int spToAdd){
String newLine = oLine;
int mark = 0;
for (int i = 0; i < posArray.length; ++i){ /*insert string at mark, shift next element by the num of elements inserted*/
if (newLine.length() > width) { System.out.println("Maths is wrong: ERROR"); System.exit(1);}
else { newLine = new StringBuilder(newLine).insert(posArray[i]+mark, sp).toString(); mark += spToAdd; }
}
return newLine;
}
public static String compFormat(int[] posArray2, String mLine, int modLeft){
String newLine = mLine;
int mark = 0;
for (int i = 0; i < modLeft; ++i){
//positions
//if position y is != y+1 insert sp modLeft times
if (posArray2[i] != posArray2[i+1] && posArray2[i] != posArray2[posArray2.length - 1]){
newLine = new StringBuilder(newLine).insert(posArray2[i]+mark, " ").toString(); mark++;
}
}
return newLine;
}
}
来源：https://stackoverflow.com/questions/34687687/most-basic-way-to-insert-a-character-into-a-string-in-java