Develop Reference

Can someone look at my code and tell me whats wrong?

So my requirement is to display a message showing yours and your friend's initials in lower case (ie. "mf and js are friends").
Here's my code
String myFullName = "Daniel Camarena";
String friendsFullName = "John Smith";
System.out.println( myFullName.toLowerCase().charAt(0)
+ myFullName.toLowerCase().charAt(7)
+ " and "
+ friendsFullName.toLowerCase().charAt(0)
+ friendsFullName.toLowerCase().charAt(5)
+ " are friends." );
The output I get is
199 and js are friends.

myFullName.toLowerCase().charAt(0) + myFullName.toLowerCase().charAt(7)
are working on ascii integer value and hence 199
The reason strings addition works for the second name is because that is part of the string formed due to this:
+ " and "
Quick fix, add an empty string at start
System.out.println("" + myFullName.toLowerCase().charAt(0)
+ myFullName.toLowerCase().charAt(7)
+ " and "
+ friendsFullName.toLowerCase().charAt(0)
+ friendsFullName.toLowerCase().charAt(5)
+ " are friends." );

System.out.println( "" + myFullName.toLowerCase().charAt(0) + myFullName.toLowerCase().charAt(7)
+ " and "
+ friendsFullName.toLowerCase().charAt(0)
+ friendsFullName.toLowerCase().charAt(5)
+ " are friends." );
Append the blank string to convert it to String and then it will start doing concanetation . As '+' is overloaded operator it is doing addition till it encounters String.

You can use following code :
String myFullName = "Daniel Camarena";
String friendsFullName = "John Smith";
String[] arrMyFullName = myFullName.toLowerCase().split(" ");
String[] arrFriendsFullName = friendsFullName.toLowerCase().split(" ");
String message = "";
for(String s : arrMyFullName)
message += s.charAt(0);
message += " and ";
for(String s : arrFriendsFullName)
message += s.charAt(0);
message += " are friends.";
System.out.println( message );
Above code also work if name is more than 2 words.

Try:
System.out.println( "" + myFullName.toLowerCase().charAt(0)
+ myFullName.toLowerCase().charAt(7)
+ " and "
+ friendsFullName.toLowerCase().charAt(0)
+ friendsFullName.toLowerCase().charAt(5)
+ " are friends." );

With this one you can have any name of friends. Instead of correcting the index which differs for each name.
String myFullName = "Daniel Camarena";
String friendsFullName = "John Smith";
String[] myNameSplit = myFullName.split(" ");
String myFirstInitial = String.valueOf(myNameSplit[0].charAt(0));
String myLastInitial = String.valueOf(myNameSplit[1].charAt(0));
String[] myFriendNameSplit = friendsFullName.split(" ");
String myFriendFirstInitial = String.valueOf(myFriendNameSplit[0].charAt(0));
String myFriendLastInitial = String.valueOf(myFriendNameSplit[1].charAt(0));
System.out.println(myFirstInitial+myLastInitial + " and " + myFriendFirstInitial+myFriendLastInitial+ " are friends");

It is adding ASCII value of d and c in output to avoid that do as following.
String myFullName = "Daniel Camarena";
String friendsFullName = "John Smith";
System.out.println( myFullName.toLowerCase().charAt(0)
+""+ myFullName.toLowerCase().charAt(7)
+ " and "
+ friendsFullName.toLowerCase().charAt(0)
+ friendsFullName.toLowerCase().charAt(5)
+ " are friends." );

How to split a NAME and ADDRESS, and print them separately

I'm starting with this String:
"NAME-RAHUL KUMAR CHOUDHARY ADDRESS-RAJDHANWAR DISTRICT-GIRIDIH STATE-JHARKHAND PIN CODE-825412"
I want to split the name and address, and print it like this:
NAME:RAHUL KUMAR CHOUDHARY , DDRESS-RAJDHANWAR DISTRICT-GIRIDIH STATE-JHARKHAND PIN CODE-825412. like this
This is what I have so far:
String str_colArow3 = colArow3.getContents();
//Display the cell contents
System.out.println("Contents of cell Col A Row 3: \""+str_colArow3 + "\"");
if(str_colArow3.contains("NAME"))
{
}
else if(str_colArow3.contains("ADDRESS"))
{
}

String string = "NAME-RAHUL KUMAR CHOUDHARY ADDRESS-RAJDHANWAR DISTRICT-GIRIDIH STATE-JHARKHAND PIN CODE-825412";
String[] parts = string.split("-");
string = "Name: " + parts[1].substring(0, parts[1].length() - 7)
+ "\nAdress: " + parts[2] + " - " + parts[3]
+ "\nPin Code: " + parts[5];
Something like this. Check out the split() method for strings, your string is a bit poorly formatted to use this, though. You have to adjust for your own needs.
Edit: Better way to do this, with different string input.
String string = "RAHUL KUMAR CHOUDHARY:RAJDHANWAR:GIRIDIH:JHARKHAND:825412";
String[] parts = string.split(":");
string = "Name: " + parts[0] + "\n"
+ "Address: " + parts[1] + "\n"
+ "District: " + parts[2] + "\n"
+ "State: " + parts[3] + "\n"
+ "Pin Code: " + parts[4] + "\n";

How to replace new lines

Unfortunately, I'm having some difficulty replacing new lines.
public class Example {
static String s = "73167176531330624919225119674426574742355349194934\n" +
"96983520312774506326239578318016984801869478851843\n" +
"85861560789112949495459501737958331952853208805511\n" +
"12540698747158523863050715693290963295227443043557\n" +
"66896648950445244523161731856403098711121722383113\n" +
"62229893423380308135336276614282806444486645238749\n" +
"30358907296290491560440772390713810515859307960866\n" +
"70172427121883998797908792274921901699720888093776\n" +
"65727333001053367881220235421809751254540594752243\n" +
"52584907711670556013604839586446706324415722155397\n" +
"53697817977846174064955149290862569321978468622482\n" +
"83972241375657056057490261407972968652414535100474\n" +
"82166370484403199890008895243450658541227588666881\n" +
"16427171479924442928230863465674813919123162824586\n" +
"17866458359124566529476545682848912883142607690042\n" +
"24219022671055626321111109370544217506941658960408\n" +
"07198403850962455444362981230987879927244284909188\n" +
"84580156166097919133875499200524063689912560717606\n" +
"05886116467109405077541002256983155200055935729725\n" +
"71636269561882670428252483600823257530420752963450".replaceAll("\\n", "");
public static void main(String[] args) {
System.out.println(s);
}
}
I would like to remove all occurrences of \n from String s. I tried looking up the answer on StackOverflow, but every post seems to have a different answer (and they are all complicated and hard to remember).
Is there a simple way of doing this?
I have also tried
replaceAll("\n", "")
replaceAll("\\\\n", "")
replaceAll(System.getProperty("line.separator"), "")
replaceAll("(\\r|\\n)", "")

"hello" + "world".replace("o","")
is same as
"hello" + ("world".replaceAll("o",""))
So replaceAll will affect only last part of your string, which in your case is
"71636269561882670428252483600823257530420752963450".replaceAll("\\n", "").
To solve this problem use parenthesis to first concatenate all string parts, and then call replace on resulting string.
static String s = (
"73167176531330624919225119674426574742355349194934\n" +
"96983520312774506326239578318016984801869478851843\n" +
"85861560789112949495459501737958331952853208805511\n" +
"12540698747158523863050715693290963295227443043557\n" +
"66896648950445244523161731856403098711121722383113\n" +
"62229893423380308135336276614282806444486645238749\n" +
"30358907296290491560440772390713810515859307960866\n" +
"70172427121883998797908792274921901699720888093776\n" +
"65727333001053367881220235421809751254540594752243\n" +
"52584907711670556013604839586446706324415722155397\n" +
"53697817977846174064955149290862569321978468622482\n" +
"83972241375657056057490261407972968652414535100474\n" +
"82166370484403199890008895243450658541227588666881\n" +
"16427171479924442928230863465674813919123162824586\n" +
"17866458359124566529476545682848912883142607690042\n" +
"24219022671055626321111109370544217506941658960408\n" +
"07198403850962455444362981230987879927244284909188\n" +
"84580156166097919133875499200524063689912560717606\n" +
"05886116467109405077541002256983155200055935729725\n" +
"71636269561882670428252483600823257530420752963450"
).replaceAll("\\n", "");
But in situation where we are not dealing with initializing field, I would prefer splitting this "one-liner" into more steps which will be more readable and you will avoid errors like one from your question:
//concatenation
String s = "....."
+"....."
:
+".....";
//modification
s = s.replaceAll("\\n","");

First of all, when you are doing
static String s = "73167176531330624919225119674426574742355349194934\n" +
"96983520312774506326239578318016984801869478851843\n" +
"85861560789112949495459501737958331952853208805511\n" +
"12540698747158523863050715693290963295227443043557\n" +
"66896648950445244523161731856403098711121722383113\n" +
"62229893423380308135336276614282806444486645238749\n" +
"30358907296290491560440772390713810515859307960866\n" +
"70172427121883998797908792274921901699720888093776\n" +
"65727333001053367881220235421809751254540594752243\n" +
"52584907711670556013604839586446706324415722155397\n" +
"53697817977846174064955149290862569321978468622482\n" +
"83972241375657056057490261407972968652414535100474\n" +
"82166370484403199890008895243450658541227588666881\n" +
"16427171479924442928230863465674813919123162824586\n" +
"17866458359124566529476545682848912883142607690042\n" +
"24219022671055626321111109370544217506941658960408\n" +
"07198403850962455444362981230987879927244284909188\n" +
"84580156166097919133875499200524063689912560717606\n" +
"05886116467109405077541002256983155200055935729725\n" +
"71636269561882670428252483600823257530420752963450".replaceAll("\\n", "");
you are only replacing the last concatenation of that string (Note: which has no "\n").
what you need to do is get rid of that replaceAll in your string declaration, and in your main method do s = s.replaceAll("\n", ""); like the following:
public static void main(String[] args) {
s = s.replaceAll("\n", "");
System.out.println(s);
}
Tested and works :D
Hope this was helpful :D

You could split and join the string before printing it like this:
public static void main(String[] args) {
System.out.println(String.join("", s.split("\n")));
}

java regex to match variable

I have the name of a java variable in a string. I want to replace it with the letter x. How can I do this java, and make sure that other words in the string are not replaced ?
For example, say my variable is res, and my string is "res = res + pres + resd + _res. I want the string to become x = x + pres + resd + _res.

You can use a word boundary to only capture whole words:
String s = "res = res + pres + resd + _res";
String var = "res";
System.out.println(s.replaceAll("\\b" + var + "\\b", "x"));
outputs x = x + pres + resd + _res

You can use the \b metacharacter to match a word boundary. (Bear in mind you'll need to use doule backslashes to escape this in Java.)
So you can do something like the following:
final String searchVar = "res";
final String replacement = "x";
final String in = "res = res + pres + resd + _res";
final String result = in.replaceAll("\\b" + searchVar + "\\b", replacement);
System.out.println(result);
// prints "x = x + pres + resd + _res"

Split string on spaces and dash but not on the value of the string

I am setting a date_string like this:
gridcell.setTag(theday + "-" + themonth + "-" + theyear + "|" + hijri_day + "-" + hijri_month + " ("+ hijri_monthno +") " + hijri_year);
And I am splitting it like this:
String date_month_year = (String) view.getTag();
String[] dateAr = date_month_year.split("-|\\||\\(|\\)|\\s+");
This is also splitting the spaces and dash in the hijri month names i.e. Rabi al-Thani or Dhul Hijjah:
private String months[] = {"Muharram","Safar","Rabi al-Awwal","Rabi al-Thani","Jumada al-Awwal","Jumada al-Thani","Rajab","Sha\'ban","Ramadhan","Shawwal","Dhul Qa\'dah","Dhul Hijjah"};
How do I split on the date_string only and not the value of the strings in the date_string?

best way is changing the date separator - to / (slash) or .(dot) If you really wanna keep like this, than after split you can check last character on string array if it is a letter join that two string into one back..
gridcell.setTag(theday + "." + themonth + "." + theyear + "|" + hijri_day + " " + hijri_month + " ("+ hijri_monthno +") " + hijri_year);
make it like this easiest way..

I tried to split your date step by step so check if this works for you
List<String> tokens=new ArrayList<String>();
String data="theday-themonth-theyear|hijri_day-Dhul Qa\'dah (hijri_monthno) hijri_year";
String[] tmp = data.split("\\|");
//System.out.println(Arrays.toString(tmp));
for (String s:tmp[0].split("-"))
tokens.add(s);
System.out.println(tokens);// -> [theday, themonth, theyear]
String[] tmp2=tmp[1].split("\\s*\\(|\\)\\s*");
//System.out.println(Arrays.toString(tmp2));
for (String s:tmp2[0].split("-",2))
tokens.add(s);
System.out.println(tokens);// -> [theday, themonth, theyear, hijri_day, Dhul Qa'dah]
tokens.add(tmp2[1]);
tokens.add(tmp2[2]);
System.out.println(tokens);// -> [theday, themonth, theyear, hijri_day, Dhul Qa'dah, hijri_monthno, hijri_year]