find the frequency of characters in a string in java
+++METHOD WITH NONDUP+++
public static String FrequencyOfChars(String str) {
String nonDup = "";
for(int i=0; i < str.length(); i++)
if(!nonDup.contains(""+str.charAt(i)))
nonDup+= ""+str.charAt(i);
String expectedResult = "";
for( int j=0;j < nonDup.length(); j++) {
int count = 0;
for(int i=0; i < str.length(); i++) {
if(str.charAt(i) == nonDup.charAt(j))
count++;
}
expectedResult +=nonDup.charAt(j)+"" + count;
}
return expectedResult;
}
+++METHOD WITH REPLACE METHOD+++
public static String FrequencyOfChars(String str) {
String expectedResult = "";
for( int j=0; j < str.length(); j++) {
int count = 0;
for(int i=0; i < str.length(); i++) {
if(str.charAt(i) == str.charAt(j)) {
count++;
}
}
expectedResult +=str.charAt(j)+"" + count;
str = str.replace(""+str.charAt(j) , "" );
}
return expectedResult;
}
+++WITH LINKED HASH SET+++
public static String FrequencyOfChars(String str) {
String b=new LinkedHashSet<>(Arrays.asList(str.split(""))).toString();
b = b.replace(", ","").replace("[","").replace("]","");
String result="";
for(int j=0; j<b.length();j++) {
int count=0;
for(int i=0; i<str.length(); i++){
if(str.substring(i, i+1).equals(""+str.charAt(j)))
count++;
}
result+=b.substring(j, j+1)+count;
}
return result;
}
++++LAST METHOD USING COLLECTIONS+++
public static String frequency(String str) {
String nonDup="", result="";
for(int i=0; i < str.length(); i++)
if(! nonDup.contains(""+str.charAt(i)))
nonDup += ""+str.charAt(i);
for(int i=0; i < nonDup.length(); i++) {
int num = Collections.frequency( Arrays.asList(str.split("") ) , ""+nonDup.charAt( i ) );
result += ""+nonDup.charAt(i) + num;
}
return result;
}