I want to print my name's letters one by one like so:
Result:
A
Af
Afs
afsh
afsha
afshan
.....
I've tried this coding but its a simple loop and it showing my complete name.
char[]aar={'a','f','s','h','a','n'};
for(int b=0; b<1;b++){
String str=new String(aar);
System.out.println(""+str);
}
It's simple. You can use the substring method of String class.
String name="yourname";
for(int i=0;i<name.length();i++)
{
System.out.println(name.substring(0,i+1));
}
It sounds like you want to print a substring of your name on each step. So start with the complete name:
String name = "Afshan";
and then loop for as many letters as there are (using String.length() to check) and then print the substring from the start to that iteration number - use name.substring(0, i + 1) to get the relevant substring where i is the variable in the loop. Read the documentation for substring carefully to see what each of the parameters means (and why you want i + 1 rather than i).
It's important to use i in the body of the loop, otherwise you will be printing the same thing on each iteration.
I won't provide the full code here, as you're trying to learn (yay) but as an aside, try to avoid using "" + ... - in your existing code, you don't need it anyway, as str is already a string, but if you do need to convert a different type into a string, use String.valueOf(x) instead. That says exactly what you want to do, whereas concatenation with an empty string doesn't.
Here's another way using nested for-loops
char[]aar={'a','f','s','h','a','n'};
//count just from 1 to the length of array
for(int a = 1; a<aar.length; a++)
{
//print elements from 0-1, 0-2 ,0-3, and so on.
for(int b=0; b<a;b++)
{
System.out.print(aar[b]);
}
System.out.println();
}
Here is an another version.
Please use meaningful names and correct indentation.
Note that the outer for loop needs the equals. Otherwise it doesn't work.
char[] chars = {'a', 'f', 's', 'h', 'a', 'n'};
for (int length = 1; length <= chars.length; length++) {
for(int i = 0; i < length; i++) {
System.out.print(chars[i]);
}
System.out.println();
}
Related
I want to reverse a string. I know there are some other methods to do it but I wanted to do in a different way. There is no error but no output when I run my code. I dont understand why "String.valueOf(word.charAt(i)" doesnt return a value? Am I missing something?
String word = "myword";
for (int i = word.length(); i <= 0; i--) {
System.out.print(String.valueOf(word.charAt(i)));
}
The first value of i is out of index. And I also fixed your code. Check below:
String word = "myword";
for(int i=word.length()-1;i>=0;i--){
System.out.print(String.valueOf(word.charAt(i)));}
Just for providing another slightly different solution:
You can use a StringBuilder to reverse a String using its method reverse().
If you have a String, you can use it to initialize the StringBuilder with it and directly reverse it.
This example additionally uses an enhanced for-loop, which always goes through all of the elements. Using that, you can get rid of checking the length of a String and you won't have to use an int i for iterating.
For your requirements, this is a suitable option because you want to reverse the whole String.
String word = "myword";
for (char c : new StringBuilder(word).reverse().toString().toCharArray()) {
System.out.println(c);
}
Note that you can use the reverse() method for printing the reversed word in one line just doing
System.out.println(new StringBuilder(word).reverse().toString());
Your code has 2 issues.
i should be initialized with word.length()-1. Other wise you will get StringIndexOutOfBoundsException
for loop condition should be >= 0.
Below is the corrected code.
String word = "myword";
for(int i=word.length()-1;i>=0;i--) {
System.out.print(word.charAt(i));
}
There is a string "hello-world!". Any character except A-Z and a-z has to stay in the same place, but letters have to be reversed. So, output would be "dlrow-olleh!".
I used string builder to design the solution, but I am curious if a string of length 12 can be declared and its characters filled in indices 5 and 11, then fill remaining with reversed letters.
Any other techniques or ideas to perform the same would be appreciated.
StringBuilder sb = new StringBuilder();
for(int i=S.length()-1; i >= 0; i--) {
String c = ""+S.charAt(i);
if(c.matches("[A-Za-z]")) {
sb.append(c);
}
}
for(int i = 0; i < S.length(); i++) {
String c = ""+S.charAt(i);
if(!c.matches("[A-Za-z]"))
sb.insert(i,c);
}
I got the output this way, but is there any way to use String here instead of StringBuilder?
You can't use String in the way you suggest, because String is immutable.
Another option, instead of StringBuilder, is to use a raw array of char. You know that the resultant string will have the same length as the source string, so you can do it like this:
Create an array using String.toCharArray.
Iterate from both ends simultaneously using indices i and j. Start index i from 0 moving forwards, and j from array length - 1, moving backwards.
Check the elements at i and j for a letter using Character.isLetter. If it's not a letter, just skip it by advancing i forwards or j backwards.
Swap the array elements at i and j.
Repeat while i < j.
Create the new string using new String(charArray)
As this looks like an exercise, I'll leave the actual coding to you.
Caveat: the above only works for strings where the Unicode code points are in the Basic Multilingual Plane (i.e. most strings to you and me). It won't work for tricky situations containing certain characters such as smileys (for more info on this potential problem, see https://dzone.com/articles/the-right-way-to-reverse-a-string-in-java).
i am trying to sort a string in the alphabetical order, however i am facing an error in the line :
sb.charAt(j)=sb.charAt(j+1);
where the compiler shows an error as expected variable; found value
the rest of the code is as follows :
import java.util.Scanner;
class a
{
public static void main(String[] agrs)
{
Scanner sc = new Scanner(System.in);
String s = sc.next();
StringBuffer sb = new StringBuffer();
sb.append(s);
for(int i = 0; i< s.length(); i++)
{
for(int j = 0; j<s.length(); j++)
{
if(s.charAt(j)>s.charAt(j+1)){
char temp = s.charAt(j);
sb.charAt(j)=sb.charAt(j+1);
sb.charAt(j+1)=temp;
}
}
}}}
kindly help me out as i'm a beginner and i cannot figure out why this issue is occurring , thank you .
This looks like a homework assignment where the goal is to sort the characters of a text being entered, so if you enter gfedbca the result should be abcdefg.
You already got a comment telling you what the problem is: StringBuffer#charAt() is not returning a reference to StringBuffer's internal array that you can change the value of. Dependent on the actual assignment you can call StringBuffers setCharAt method or you can go another approach by converting the text to sort to a char array and do the sorting in there. There are actually helper-classes in the JVM, that do that for you, have a look e.g. at the class java.util.Arrays
As already answered by many, the issue is in charAt(index) you are using, as this returns the character at the given index rather than setting a char at the index position.
My answer is to divert your approach of sorting. For simpler solutions, where smaller data sets (like your problem) are used, you should use the predefined sorting algorithms, like Insertion Sort
You may get help for the algo from here: http://www.geeksforgeeks.org/insertion-sort/
StringBuffer's charAt returns just the value of the char at the index, if you want to swap two chars you need to use setter for that, so you possible want to do somtehing like:
for(int j = 0; j < s.length() - 1; j++) {
if(s.charAt(j) > s.charAt(j + 1)) {
char temp = s.charAt(j);
sb.setCharAt(j, sb.charAt(j + 1));
sb.setCharAt(j + 1, temp);
}
}
This method can only return values and can not set values, I guess you might want to use this method:
setCharAt()
It can meet your requirement
I am learning Java and looking for a comprehensive code of multiplying the elements from 2 arrays, possibly without importing anything to achieve it.
In Python it's quite easy:
a=['a','b','c','d']
b=[1,2,3,4]
[x*y for x,y in zip(a,b)]
['a', 'bb', 'ccc', 'dddd']
How can I achieve the same thing in Java, when the first array is an array of strings and the second is integers?
I'm afraid Java isn't going to support this kind of thing natively, and you'll need to perform some of your own logic to implement it. Let's say you've got your String[]..
String[] a = {"a", "b", "c", "d"};
And you've got your int[]..
int[] b = {1,2,3,4};
Next, you'll need to check that the arrays are the same size.
if(a.length == b.length) {
// Continue.
}
Then you need to implement a loop, to go through each item in the arrays.
for(int x = 0; x < a.length; x++)
{
// Some looping code.
}
And you're going to grab each item.
String value = a[x];
int multiplier = b[x];
If you're not importing anything, you declare the total value:
String total = "";
But if you're allowing for a StringBuilder, then you'll import it and declare..
StringBuilder total = new StringBuilder();
NOTE: StringBuilder is strongly recommended here.
And then you're looping multiplier amount of times..
for(int y = 0; y < multiplier; y++)
{
// If you use StringBuilder..
total.append(value);
// If you don't..
total += value;
}
// If you use StringBuilder..
a[x] = total.toString();
// If you don't...
a[x] = total;
This will set the value of a[x] to the repeated String.
NOTE: Something that's also important is leaning good practise. If you're using Java code, it's considered terrible practise to repeatedly concatenate String objects. StringBuilder is more efficient, and is the Java standard. I would strongly recommend using this.
Have fun putting it all together!!
To create string filled with multiple instances of same character like "ccc" you can firs create array of characters which will hold only 3 characters like
char[] myCharacters = new char[3];
Now this array is filled with zeroes ('\0'), so you need to fill it with desired character 'c'. You simply do it using for loop
for (int i = 0; i<myCharacters; i++){
myCharacters[i] = 'c';
}
After this your array will contain ['c', 'c', 'c'].
Now you can use this array to create string using characters from it. To do so you just need to pass this array to String constructor like
String myString = new String(myCharacters);
And there you go. Now you have "ccc" String. Repeat these steps for each pair of elements from a and b arrays.
You can also use shorter version which kinds of do the same
String myString = new String(new char[3]).replace('\0','c');//will produce "ccc"
So, I'm in need of help on my homework assignment. Here's the question:
Write a static method, getBigWords, that gets a String parameter and returns an array whose elements are the words in the parameter that contain more than 5 letters. (A word is defined as a contiguous sequence of letters.) So, given a String like "There are 87,000,000 people in Canada", getBigWords would return an array of two elements, "people" and "Canada".
What I have so far:
public static getBigWords(String sentence)
{
String[] a = new String;
String[] split = sentence.split("\\s");
for(int i = 0; i < split.length; i++)
{
if(split[i].length => 5)
{
a.add(split[i]);
}
}
return a;
}
I don't want an answer, just a means to guide me in the right direction. I'm a novice at programming, so it's difficult for me to figure out what exactly I'm doing wrong.
EDIT:
I've now modified my method to:
public static String[] getBigWords(String sentence)
{
ArrayList<String> result = new ArrayList<String>();
String[] split = sentence.split("\\s+");
for(int i = 0; i < split.length; i++)
{
if(split[i].length() > 5)
{
if(split[i].matches("[a-zA-Z]+"))
{
result.add(split[i]);
}
}
}
return result.toArray(new String[0]);
}
It prints out the results I want, but the online software I use to turn in the assignment, still says I'm doing something wrong. More specifically, it states:
Edith de Stance states:
⇒ You might want to use: +=
⇒ You might want to use: ==
⇒ You might want to use: +
not really sure what that means....
The main problem is that you can't have an array that makes itself bigger as you add elements.
You have 2 options:
ArrayList (basically a variable-length array).
Make an array guaranteed to be bigger.
Also, some notes:
The definition of an array needs to look like:
int size = ...; // V- note the square brackets here
String[] a = new String[size];
Arrays don't have an add method, you need to keep track of the index yourself.
You're currently only splitting on spaces, so 87,000,000 will also match. You could validate the string manually to ensure it consists of only letters.
It's >=, not =>.
I believe the function needs to return an array:
public static String[] getBigWords(String sentence)
It actually needs to return something:
return result.toArray(new String[0]);
rather than
return null;
The "You might want to use" suggestions points to that you might have to process the array character by character.
First, try and print out all the elements in your split array. Remember, you do only want you look at words. So, examine if this is the case by printing out each element of the split array inside your for loop. (I'm suspecting you will get a false positive at the moment)
Also, you need to revisit your books on arrays in Java. You can not dynamically add elements to an array. So, you will need a different data structure to be able to use an add() method. An ArrayList of Strings would help you here.
split your string on bases of white space, it will return an array. You can check the length of each word by iterating on that array.
you can split string though this way myString.split("\\s+");
Try this...
public static String[] getBigWords(String sentence)
{
java.util.ArrayList<String> result = new java.util.ArrayList<String>();
String[] split = sentence.split("\\s+");
for(int i = 0; i < split.length; i++)
{
if(split[i].length() > 5)
{
if(split[i].matches("[a-zA-Z]+"))
{
result.add(split[i]);
}
if (split[i].matches("[a-zA-Z]+,"))
{
String temp = "";
for(int j = 0; j < split[i].length(); j++)
{
if((split[i].charAt(j))!=((char)','))
{
temp += split[i].charAt(j);
//System.out.print(split[i].charAt(j) + "|");
}
}
result.add(temp);
}
}
}
return result.toArray(new String[0]);
}
Whet you have done is correct but you can't you add method in array. You should set like a[position]= spilt[i]; if you want to ignore number then check by Float.isNumber() method.
Your logic is valid, but you have some syntax issues. If you are not using an IDE like Eclipse that shows you syntax errors, try commenting out lines to pinpoint which ones are syntactically incorrect. I want to also tell you that once an array is created its length cannot change. Hopefully that sets you off in the right directions.
Apart from syntax errors at String array declaration should be like new String[n]
and add method will not be there in Array hence you should use like
a[i] = split[i];
You need to add another condition along with length condition to check that the given word have all letters this can be done in 2 ways
first way is to use Character.isLetter() method and second way is create regular expression
to check string have only letter. google it for regular expression and use matcher to match like the below
Pattern pattern=Pattern.compile();
Matcher matcher=pattern.matcher();
Final point is use another counter (let say j=0) to store output values and increment this counter as and when you store string in the array.
a[j++] = split[i];
I would use a string tokenizer (string tokenizer class in java)
Iterate through each entry and if the string length is more than 4 (or whatever you need) add to the array you are returning.
You said no code, so... (This is like 5 lines of code)