Use Apache's common library. Free your brain from these stuffs and avoid Null Pointer & Index Out Of Bound Exceptions

Step 1:

Import apache's common lang library by putting this in build.gradle dependencies

compile 'org.apache.commons:commons-lang3:3.6'

Step 2:

If you are sure that your string is all lower case, or all you need is to initialize the first letter, directly call

StringUtils.capitalize(yourString);

If you want to make sure that only the first letter is capitalized, like doing this for an enum, call toLowerCase() first and keep in mind that it will throw NullPointerException if the input string is null.

StringUtils.capitalize(YourEnum.STUFF.name().toLowerCase());
StringUtils.capitalize(yourString.toLowerCase());

Here are more samples provided by apache. it's exception free

StringUtils.capitalize(null)  = null
StringUtils.capitalize("")    = ""
StringUtils.capitalize("cat") = "Cat"
StringUtils.capitalize("cAt") = "CAt"
StringUtils.capitalize("'cat'") = "'cat'"

Note:

WordUtils is also included in this library, but is deprecated. Please do not use that.

Java:

simply a helper method for capitalizing every string.

public static String capitalize(String str)
{
    if(str == null || str.length()<=1) return str;
    return str.substring(0, 1).toUpperCase() + str.substring(1);
}

After that simply call str = capitalize(str)

Kotlin:

str.capitalize()

if you use SPRING:

import static org.springframework.util.StringUtils.capitalize;
...


    return capitalize(name);

IMPLEMENTATION: org/springframework/util/StringUtils.java#L535-L555

REF: javadoc-api/org/springframework/util/StringUtils.html#capitalize

NOTE: If you already have Apache Common Lang dependency, then consider using their StringUtils.capitalize as other answers suggest.

IT WILL WORK 101%

public class UpperCase {

    public static void main(String [] args) {

        String name;

        System.out.print("INPUT: ");
        Scanner scan = new Scanner(System.in);
        name  = scan.next();

        String upperCase = name.substring(0, 1).toUpperCase() + name.substring(1);
        System.out.println("OUTPUT: " + upperCase); 

    }

}

Here is my detailed article on the topic for all possible options Capitalize First Letter of String in Android

Method to Capitalize First Letter of String in Java

public static String capitalizeString(String str) {
        String retStr = str;
        try { // We can face index out of bound exception if the string is null
            retStr = str.substring(0, 1).toUpperCase() + str.substring(1);
        }catch (Exception e){}
        return retStr;
}

Method to Capitalize First Letter of String in KOTLIN

fun capitalizeString(str: String): String {
        var retStr = str
        try { // We can face index out of bound exception if the string is null
            retStr = str.substring(0, 1).toUpperCase() + str.substring(1)
        } catch (e: Exception) {
        }
        return retStr
}

TO get First letter capital and other wants to small you can use below code. I have done through substring function.

String currentGender="mAlE";
    currentGender=currentGender.substring(0,1).toUpperCase()+currentGender.substring(1).toLowerCase();

Here substring(0,1).toUpperCase() convert first letter capital and substring(1).toLowercase() convert all remaining letter into a small case.

OUTPUT:

Male

Existing answers are either

• incorrect: they think that char is a separate character (code point), while it is a UTF-16 word which can be a half of a surrogate pair, or
• use libraries which is not bad itself but requires adding dependencies to your project, or
• use Java 8 Streams which is perfectly valid but not always possible.

Let's look at surrogate characters (every such character consist of two UTF-16 words — Java chars) and can have upper and lowercase variants:

IntStream.rangeClosed(0x01_0000, 0x10_FFFF)
    .filter(ch -> Character.toUpperCase(ch) != Character.toLowerCase(ch))
    .forEach(ch -> System.out.print(new String(new int[] { ch }, 0, 1)));

Many of them may look like 'tofu' (□) for you but they are mostly valid characters of rare scripts and some typefaces support them.

For example, let's look at Deseret Small Letter Long I (), U+10428, "\uD801\uDC28":

System.out.println("U+" + Integer.toHexString(
        "\uD801\uDC28".codePointAt(0)
)); // U+10428

System.out.println("U+" + Integer.toHexString(
        Character.toTitleCase("\uD801\uDC28".codePointAt(0))
)); // U+10400 — ok! capitalized character is another code point

System.out.println("U+" + Integer.toHexString(new String(new char[] {
        Character.toTitleCase("\uD801\uDC28".charAt(0)), "\uD801\uDC28".charAt(1)
}).codePointAt(0))); // U+10428 — oops! — cannot capitalize an unpaired surrogate

So, a code point can be capitalized even in cases when char cannot be. Considering this, let's write a correct (and Java 1.5 compatible!) capitalizer:

@Contract("null -> null")
public static CharSequence capitalize(CharSequence input) {
    int length;
    if (input == null || (length = input.length()) == 0) return input;

    return new StringBuilder(length)
            .appendCodePoint(Character.toTitleCase(Character.codePointAt(input, 0)))
            .append(input, Character.offsetByCodePoints(input, 0, 1), length);
}

And check whether it works:

public static void main(String[] args) {
    // ASCII
    System.out.println(capitalize("whatever")); // w -> W

    // UTF-16, no surrogate
    System.out.println(capitalize("что-то")); // ч -> Ч

    // UTF-16 with surrogate pairs
    System.out.println(capitalize("\uD801\uDC28")); //  -> 
}

See also:

• surrogate pairs What is a "surrogate pair" in Java?
• upper case vs. title case https://stackoverflow.com/a/47887432/3050249

Current answers are either incorrect or over-complicate this simple task. After doing some research, here are two approaches I come up with:

1. String's substring() Method

public static String capitalize(String str) {
    if(str== null || str.isEmpty()) {
        return str;
    }

    return str.substring(0, 1).toUpperCase() + str.substring(1);
}

Examples:

System.out.println(capitalize("java")); // Java
System.out.println(capitalize("beTa")); // BeTa
System.out.println(capitalize(null)); // null

2. Apache Commons Lang

The Apache Commons Lang library provides StringUtils the class for this purpose:

System.out.println(StringUtils.capitalize("apache commons")); // Apache commons
System.out.println(StringUtils.capitalize("heLLO")); // HeLLO
System.out.println(StringUtils.uncapitalize(null)); // null

Don't forget to add the following dependency to your pom.xml file:

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.9</version>
</dependency>

Simple solution! doesn't require any external library, it can handle empty or one letter string.

private String capitalizeFirstLetter(@NonNull String str){
        return str.length() == 0 ? str
                : str.length() == 1 ? str.toUpperCase()
                : str.substring(0, 1).toUpperCase() + str.substring(1).toLowerCase();
}

If Input is UpperCase ,then Use following :

str.substring(0, 1).toUpperCase() + str.substring(1).toLowerCase();

If Input is LowerCase ,then Use following :

str.substring(0, 1).toUpperCase() + str.substring(1);

System.out.println(Character.toString(A.charAt(0)).toUpperCase()+A.substring(1));

P.S = a is a string.

Yet another example, how you can make the first letter of the user input capitalized:

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String string = br.readLine();
// handle supplementary characters
IntStream.concat(
        IntStream.of(string.codePointAt(0))
                .map(Character::toUpperCase), string.codePoints().skip(1)
)
.forEach(cp -> System.out.print(Character.toChars(cp)));

Since you first get Char from your original string. You cant use String properties on char so just use to upper first and then use charAt

String s1 = name.toUppercase().charAt(0);

Just reworked Jorgesys code and added few checks because of few cases related to String length. Don't do for null reference check in my case.

 public static String capitalizeFirstLetter(@NonNull String customText){
        int count = customText.length();
        if (count == 0) {
            return customText;
        }
        if (count == 1) {
            return customText.toUpperCase();
        }
        return customText.substring(0, 1).toUpperCase() + customText.substring(1).toLowerCase();
    }

The code i have posted will remove underscore(_) symbol and extra spaces from String and also it will capitalize first letter of every new word in String

private String capitalize(String txt){ 
  List<String> finalTxt=new ArrayList<>();

  if(txt.contains("_")){
       txt=txt.replace("_"," ");
  }

  if(txt.contains(" ") && txt.length()>1){
       String[] tSS=txt.split(" ");
       for(String tSSV:tSS){ finalTxt.add(capitalize(tSSV)); }  
  }

  if(finalTxt.size()>0){
       txt="";
       for(String s:finalTxt){ txt+=s+" "; }
  }

  if(txt.endsWith(" ") && txt.length()>1){
       txt=txt.substring(0, (txt.length()-1));
       return txt;
  }

  txt = txt.substring(0,1).toUpperCase() + txt.substring(1).toLowerCase();
  return txt;
}

One of the answers was 95% correct, but it failed on my unitTest @Ameen Maheen's solution was nearly perfect. Except that before the input gets converted to String array, you have to trim the input. So the perfect one:

private String convertStringToName(String name) {
        name = name.trim();
        String[] words = name.split(" ");
        StringBuilder sb = new StringBuilder();
        if (words[0].length() > 0) {
            sb.append(Character.toUpperCase(words[0].charAt(0)) + words[0].subSequence(1, words[0].length()).toString().toLowerCase());
            for (int i = 1; i < words.length; i++) {
                sb.append(" ");
                sb.append(Character.toUpperCase(words[i].charAt(0)) + words[i].subSequence(1, words[i].length()).toString().toLowerCase());
            }
        }
        return sb.toString();
    }

Given answers is for capitalize the first letter of one word only. use following code to capitalize a whole string.

public static void main(String[] args) {
    String str = "this is a random string";
    StringBuilder capitalizedString = new StringBuilder();
    String[] splited = str.trim().split("\\s+");

    for (String string : splited) {         
        String s1 = string.substring(0, 1).toUpperCase();
        String nameCapitalized = s1 + string.substring(1);

        capitalizedString.append(nameCapitalized);
        capitalizedString.append(" ");
    }
    System.out.println(capitalizedString.toString().trim());
}

output : This Is A Random String

Use replace method.

String newWord = word.replace(String.valueOf(word.charAt(0)), String.valueOf(word.charAt(0)).toUpperCase());

One approach.

String input = "someТекст$T%$4čřЭ"; //Enter your text.
if (input == null || input.isEmpty()) {
    return "";
}

char [] chars = input.toCharArray();
chars[0] = chars[0].toUpperCase();
String res = new String(chars);
return res;

The drawback of this method is that if inputString is long, you will have three objects of such length. The same as you do

String s1 = input.substring(1).toUpperCase();
String s2 = input.substring(1, lenght);
String res = s1 + s2;

Or even

//check if not null.
StringBuilder buf = new StringBuilder(input);
char ch = buf.getCharAt(0).toUpperCase();
buf.setCharAt(0, ch);
return buf.toString();

This code to capitalize each word in text!

public String capitalizeText(String name) {
    String[] s = name.trim().toLowerCase().split("\\s+");
    name = "";
    for (String i : s){
        if(i.equals("")) return name; // or return anything you want
        name+= i.substring(0, 1).toUpperCase() + i.substring(1) + " "; // uppercase first char in words
    }
    return name.trim();
}

import java.util.*;
public class Program
{
    public static void main(String[] args) 
      {
        Scanner sc=new Scanner(System.in);
        String s1=sc.nextLine();
        String[] s2=s1.split(" ");//***split text into words***
        ArrayList<String> l = new ArrayList<String>();//***list***
        for(String w: s2)
        l.add(w.substring(0,1).toUpperCase()+w.substring(1)); 
        //***converting 1st letter to capital and adding to list***
        StringBuilder sb = new StringBuilder();//***i used StringBuilder to convert words to text*** 
        for (String s : l)
          {
             sb.append(s);
             sb.append(" ");
          }
      System.out.println(sb.toString());//***to print output***
      }
}

i have used split function to split the string into words then again i took list to get the first letter capital in that words and then i took string builder to print the output in string format with spaces in it

To capitalize the first letter of the input string, we first split the string on space and then use the collection transformation procedure provided by map

<T, R> Array<out T>.map(

   transform: (T) -> R

): List<R>

to transform, each split string to first in lowercase then capitalize the first letter. This map transformation will return a list that needs to convert into a string by using joinToString function.

KOTLIN

fun main() {
    
    /*
     * Program that first convert all uper case into lower case then 
     * convert fist letter into uppercase
     */
    
    val str = "aLi AzAZ alam"
    val calStr = str.split(" ").map{it.toLowerCase().capitalize()}
    println(calStr.joinToString(separator = " "))
}

OUTPUT

Here is solution from my side, with all the conditions check.

   import java.util.Objects;

public class CapitalizeFirstCharacter {

    public static void main(String[] args) {

        System.out.println(capitailzeFirstCharacterOfString("jwala")); //supply input string here
    }

    private static String capitailzeFirstCharacterOfString(String strToCapitalize) {

        if (Objects.nonNull(strToCapitalize) && !strToCapitalize.isEmpty()) {
            return strToCapitalize.substring(0, 1).toUpperCase() + strToCapitalize.substring(1);
        } else {
            return "Null or Empty value of string supplied";

        }

    }

}

• character char can't store in String.
• char and String can't concatenate.
• String.valueOf() use to convert char to String

Input

india

Code

String name = "india";
char s1 = name.charAt(0).toUppercase()); // output: 'I'
System.out.println(String.valueOf(s1) + name.substring(1)); // output: "I"+ "ndia";

Output

India

'Firstly you need to do this way--->

//enter here your string values
String output = str.substring(0, 1).toUpperCase() + str.substring(1);

Output will in this way --->
Enter here your string values