java programmes Answers for the questions above.

1. Print duplicate characters from string?

sol.
         public  void  findduplicaearray() {
String str="abbcccdddd";
Map<Character,Integer>mp=new HashMap<>();
Map<Character,Integer>dupl=new HashMap<>();
        for(int i=0;i<str.length();i++){

if(mp.containsKey(str.charAt(i))){

   int count=mp.get(str.charAt(i));
                    count++;
   

   mp.put(str.charAt(i),count);}

else{

mp.put(str.charAt(i),1);
}

}
        Set<Map.Entry<Character,Integer>>set=mp.entrySet();
        for(Map.Entry<Character,Integer>st:set) {
        if(st.getValue()>1) {
        dupl.put(st.getKey(),st.getValue());
       
        }
     
       
        }
       System.out.println(dupl);
   
   
}

*********************************************************************************Check two strings are anagram are not?

sol:
String str1="ravi";
String str2="ivar";
       

             if(str1.length()==Str2.length()){
                   for(int i=0;i<str1.length();i++){
                       for(int j=0;j<str2.length();j++){
    if(str1.charAt(i)==str2.charAt(j)){
system.out.println("anagram")}
else{
system.out.println("not anagram")}


**************************************************************************
2.check two strings are anagram or not?
sol:
public static boolean checkanagramornot(String str1,String str2) {
if(str1.length()!=str2.length()){
return false;
}
char[]Array1=str1.toCharArray();
    char[]Array2=str2.toCharArray();
Arrays.sort(Array1);
Arrays.sort(Array2);
if(Arrays.equals(Array1, Array2)) {
return true;
}
else {
return false;
}


}

***************************************************************
3.programme to count number of words in a string?
sol:
public static int countnumberofwords(String str) {
String[]arr=str.split(" ");
return arr.length ;

}
**************************************************************
4.number of occurence of a given character in a string with out loop?
sol:
   public static int occurenceofcharacter(String ch,String s){

int count=s.length()-s.replaceAll(ch,"").length();

                     return count;
}


************************************************************
5.Reverse string
sol:
  public static String reversestring(String str){
String s="";
for(int i=str.length()-1;i>=0;i--){
 System.out.println(str.charAt(i));
  s= s+str.charAt(i);
}
return s;
}

***********************************************************************
6.Remove all whit spaces from string?
   sol:

public String removewhitspaces(String str){
String s=str.replaceall(" ","");
return s;
*************************************************************************
7.Firstnonrepeatedcharacter?
sol:

public static char nonrepeatedcharacter(String s){
char  c = 0;
         for (int i = 0; i < s.length(); i++) {
boolean unique = true;
             for (int j = 0; j < s.length(); j++) {
                 if (i!=j && s.charAt(i) == s.charAt(j)) {
                     unique = false;
                     break;
                 } }
             if (unique) {
                 System.out.println("First non repeated characted in String \""
                 + s + "\" is:" + s.charAt(i));
                 c=s.charAt(i);
                 break;
             }
         }return c;
*********************************************************************************
8.Using iteration and recursion

sol:
public static void onlydigits(char[]chr){

Stack<Character>stack=new Stack<>();
for(int i=0;i<chr.length;i++){
    stack.push(chr[i]);
 for(int j=0;j<chr.length;j++){
   str[i] = st.peek(); 
    st.pop(); 
********************************************************************************
9.String contains digit?
sol:

public static boolean isdigit(String s){
for(int i=0;i<s.length();i++){
  if(Character.isdigit(s.charAt(i))  {
system.out.println("is digit");}
else{
system.out.println("is not digit");
}
  }
********************************************************************************
10. Reverse a string with preserving the position of spaces ?
sol:
      public static void getreversestringwithoutchangingspecialcharacters(String str){

       char[] inputArray = str.toCharArray();
       char[] result = new char[inputArray.length];

       // Mark spaces in result       for (int i = 0; i < inputArray.length; i++) {
           if (inputArray[i] == ' ') {
               result[i] = ' ';
           }
       }

       // Traverse input string from beginning       // and put characters in result from end       int j = result.length - 1;
       for (int i = 0; i < inputArray.length; i++) {

           // Ignore spaces in input string           if (inputArray[i] != ' ') {

               // ignore spaces in result.               if (result[j] == ' ') {
                   j--;
               }
               result[j] = inputArray[i];
               j--;
           }
       }
       System.out.println(String.valueOf(result));
   }

    public static void main(String[] args) {
        getreversestringwithoutchangingspecialcharacters("parupalli ravi naidu");
}}

*********************************************************************************
11..reverse a each word of string ?
sol:

public static void getreversestringwithoutchangingspecialcharacters(String str) {
   String[]arr=str.split(" ");
    String reverse=" ";

   for(int i=0;i<arr.length;i++){
     for(int j=arr[i].length()-1;j>=0;j--){
        reverse=reverse+arr[i].charAt(j);
     }


   }
    
}


public static void main(String[] args) {
    getreversestringwithoutchangingspecialcharacters("parupalli ravi naidu");
}