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Change the case of every alternate char [closed]

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I want to write a code in Java which does make changes to case of a alphabet character in an alternating fashion(either make it lowercase or uppercase)
For Example:
changeCapitalization("hey 123 ABC idk"); // hEy 123 AbC iDk
changeCapitalization("abcdef ghijk 12 abc"); // aBcDeF gHiJk 1 AbC

You can use StringBuilder to build new string and boolean marker to change between lower/upper letter case.
public static String changeCapitalization(String str) {
StringBuilder buf = new StringBuilder(str.length());
boolean upperCase = false;
for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
if (Character.isLetter(ch)) {
buf.append(upperCase ? Character.toUpperCase(ch) : Character.toLowerCase(ch));
upperCase = !upperCase;
} else
buf.append(ch);
}
return buf.toString();
}

public static void main(String[] args) {
String str ="hello THERE";
String new_str="";
for(int i=0;i<str.length();i++){
String c =Character.toString(str.charAt(i));
if(Character.isUpperCase(str.charAt(i))){
c=c.toLowerCase();
new_str+=c;
}
else if(Character.isLowerCase(str.charAt(i))){
c=c.toUpperCase();
new_str+=c;
}
else if(c.equals(" ")){
new_str+=" ";
}
}
System.out.println(str);
System.out.println(new_str);
}

How to add spaces in between numbers contained inside a string? [closed]

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I have string as "DOC_87654321 -ABC76543". What I want is add spaces in between numbers. The result should be "DOC_8 7 6 5 4 3 2 1-ABC7 6 5 4 3". How can it possible?

Try this
String str = "DOC_87654321 -ABC76543";
StringBuilder sb = new StringBuilder();
for (int i = 0; i < str.length(); i++) {
char c = str.charAt(i);
if (Character.isDigit(c)) {
sb.append(c + " ");
} else {
sb.append(c);
}
}
Log.e("DATA",sb.toString());

you can use this:
String str = "DOC_87654321 -ABC76543- 959565412";
String finalStr = "";
String[] split = str.split("-");
for (int i = 0; i < split.length; i++) {
finalStr +=
split[i]
.replaceAll("([0-9])", "$1 ")
.trim()
+ (i != split.length - 1 ? '-' : "");
}
System.out.println("finalStr = " + finalStr);

In case if you don't wanna use Character.isDigit() you can compare their ascii decimal values and use it like this
public static void main(String[] args) {
String str = "DOC_87654321 -ABC76543";
StringBuilder string = new StringBuilder();
for(int i=0;i<str.length();i++) {
if(str.charAt(i) >= 48 && str.charAt(i) <=57) {
string.append(str.charAt(i)+" ");
}else {
string.append(str.charAt(i));
}
}
System.out.println(string.toString());
}

How to rewrite code from array to arraylist without using .asList? [closed]

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Teacher gave this code and said to rewrite it so that there is no array and just rewritten to arraylist. I am not allowed to use .asList. Any idea how to do this?
public APCSStudents(Student[] sarray) {
for (int i = 0; i < sarray.length; i++)
studentarray[i] = sarray[i];
}
public Student bestStudent() {
Student s = studentarray[0];
for (int i = 0; i < studentarray.length; i++){
if (studentarray[i].getPoints() > s.getPoints()) {
s = studentarray[i];
}
}
return s;
}

Just hints, equivalences:
Student[] studentsArray = new Student(100);
List<Student> students = new ArrayList<>();
studentsArray.length;
students.size();
// See also students.isEmpty()
s = studentsArray[i];
s = students.get(i);
studentsArray[i] = s;
students.set(i, s);
students.add(s); // Adding to a growing array
The Javadoc of List may prove interesting.

What would the java code be for sorting the characters in each word of a string? [closed]

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I don't want a string with the words sorted alphabetically. I need the letters of each word arranged alphabetically, but the order of words to remain the same.
Eg: Input string: welcome to java, Output string: ceelmow ot aajv

Try this:
String str = "welcome to java";
String strs[] = str.split(" ");
char[] ch;
StringBuilder strBuilder = new StringBuilder(str.length());
for (int i=0; i<strs.length; i++) {
ch = strs[i].toCharArray();
Arrays.sort(ch);
strBuilder.append(ch);
if (i != strs.length - 1) {
strBuilder.append(" ");
}
}
System.out.println(strBuilder.toString());

This could be solved using 5 steps
1) Split the String to words using foo.split(" ")
2) Get all the characters in the String using char[] bar=foo.toCharArray()
3) Sort the array using Arrays.sort(bar)
4) Turn the characters in a String using new String(bar)
5) Put all the characters back to a sentence
Don't forget to mind that capitals will come before not-capitals
Let me know if it works (or not)
Happy coding :) -Charlie

import java.util.Arrays;
public class StackOverflowExample {
public static void main(String[] args) {
String s = "welcome to java";
String[] words = s.split(" ");
StringBuilder sb = new StringBuilder();
for (int i = 0; i < words.length; i++) {
if (i != 0) {
sb.append(" ");
}
char[] wordCharArray = words[i].toCharArray();
Arrays.sort(wordCharArray);
sb.append(wordCharArray);
}
System.out.println(sb.toString());
}
}

Printing out vowels using For Loop [closed]

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import java.util.Random;
public class Test{
public static void main(String[] args){
final Random r = new Random();
String ch = "aeiouycbdfgh";
int len = r.nextInt(10) + 10;
StringBuffer sb = new StringBuffer();
for (int i=0; i<len; i++){
sb.append(ch.charAt(r.nextInt(ch.length())));
}
System.out.println("String:" + sb);
System.out.println("Vowels:");
outputVowels(sb.toString());
}
public static void outputVowels(String s){
How do i make a for loop that will output the vowels of the ch string each in a different line?
edit: the program is meant to output
a
e
i
o
u

First prepare global vowel set - for fast access:
Set<Character> vowelSet = new HashSet<>();
vowelSet.addAll(Arrays.asList('a', 'e', 'i', 'o', 'u'));
Second, you can write scanning loop like this:
String str = "ahjuekjdf";
for (int i=0; i<str.length(); i++) {
char c = str.charAt(i);
if(vowelSet.contains(c)) {
System.out.println(c);
}
}

You can directly use Regex
public class Test {
public static void main(String[] args) {
String s = "Ankur";
s = s.replaceAll("[^aeiouAEIOU]", "");
System.out.println(s);
}
}
Output
Au

change your loop to
for (int i=0; i<len; i++) {
char c = sh.charAt(i);
if ((c=='a')||(c=='e')||(c=='i')||(c=='o')||(c=='u')) {
sb.append(ch.charAt(r.nextInt(ch.length())));
}
}

for(char v : vowel){
if(ch == v){
cout <<ch<<" is vowel";
break;
}
else{
cout <<ch<<" is consonant";
break;
}
}