String (11 to 20) Programs

100 Java String Programming Questions Series(11 to 20)

11. Write a program to convert string into LowerCase.

class StringToLowerCase {
  public static void main(String[] args) {
    String str = "ApplE";
    char c;;
    System.out.println("Input given is - " + str);
    for (int i = 0; i < str.length(); i++) {
      c = str.charAt(i);
      if (str.charAt(i) >= 65 && str.charAt(i) <= 90) {
        c = (char)(c + 32);
        System.out.print(c);
      } else
        System.out.print(c);
    }

    //System.out.println(str.toLowerCase());

  }
}

12.Write a program to convert uppercase letters to lowercase and vice versa..

	public class ToggleCase {
    public static void main(String[] args) {
        String text = "HeLLo WoRLd JaVa123";
         System.out.println("Input text is : "  + text);
        System.out.print("Toggled: ");
        for (int i = 0; i < text.length(); i++) {
            char ch = text.charAt(i);

            if (ch >= 'A' && ch <= 'Z') {
                ch = (char)(ch + 32);
            } else if (ch >= 'a' && ch <= 'z') {
                ch = (char)(ch - 32);
            }
            System.out.print(ch); 
        }
    }
}

13.Write a program to remove vowels from a string.

	public class RemoveVowels {
    public static void main(String[] args) {
        String text = "HeLLo WoRLd JaVa123";
        System.out.println("Input text is : "  + text);
        System.out.print("Vowels Removed : ");
        int i=0;
        while(i
 

14.Write a program to remove spaces from a string.

	public class RemoveSpaces {
    public static void main(String[] args) {
        String text = "HeLLo Wo    RLd JaVa1   23";
        System.out.println("Input text is : "  + text);
        System.out.print("Spaces Removed : ");
        int i=0;
        while(i
 

15.Write a program to remove digits from a string.

public class Removedigits {
    public static void main(String[] args) {
        String text = "HeLLo2025 WoRLd JaVa1   23";
        System.out.println("Input text is : "  + text);
        System.out.print("Spaces Removed : ");
        int i=0;
        while(i='0' && ch<='9'){
                i++;
            }
            else{
                System.out.print(ch);
                i++;
            }
        }
        String text1 = "a1b2c3d4e5";
         System.out.println("\nInput text is : "+text1);
        String result1 = text1.replaceAll("[0-9]", "");
        System.out.println("Result: " + result1);
    }
}

16.Write a program to remove special cahracters from a string.

	public class RemoveSpecialCharacter {
    public static void main(String[] args) {
        String text = "HeLLo@2025+WoRLd=JaVa1*$23";
        System.out.println("Input text is : "  + text);
        System.out.print("Spaces Removed : ");
        int i=0;
        while(i=48 && ch<=57||ch>=65 && ch<=90||ch>=97 && ch<=122){
                 System.out.print(ch);
                i++;
            }
            else{
               
                i++;
            }
        }
    }
}

17.Write a program to replace spaces with underscores in a string.

	public class ReplaceSpaces_{
    public static void main(String[] args) {
        String text = "Hello World Java Program";
        System.out.println("Modified: ");
        for (int i = 0; i < text.length(); i++) {
            char ch = text.charAt(i);
            if (ch == ' ') {
                System.out.print('_');
            } else {
                System.out.print(ch);
            }
        }
        String text1 = "He   llo Wor   ld J ava Program";
        System.out.println("\nOriginal: " + text1);
        String result1 = text.replace(' ', '_');
        System.out.println("Modified: " + result1);
    
        
    }
}

18.Write a program to replace a character in a string.

public class ReplaceSpaces_{
    public static void main(String[] args) {
        String text = "I have a cat";
        System.out.println("\nOriginal: " + text);
                System.out.println("Modified: ");
        for (int i = 0; i < text.length(); i++) {
            char ch = text.charAt(i);
            if (ch == 'c') {
                System.out.print('r');
            } else {
                System.out.print(ch);
            }
        }
        String text1 = "the sun is hot";
        System.out.println("\nOriginal: " + text1);
        String result1 = text1.replace('s','r');
        System.out.println("Modified: " + result1);
    }
}

19.Write a program to check strings are equal.

class EqualsCheck {
    public static void main(String[] args) {
        String str1="apple";
        String str2="apple";
        String str3=new String("apple");
        String str4="applE";
        if(str1==str2)
        System.out.println("Strings are equal");
        else
        System.out.println("String are not Equal");
        if(str1==str3)
        System.out.println("Strings are equal");
        else
        System.out.println("String are not Equal");
         if(str1.equals(str3))
        System.out.println("Strings are equal");
        else
        System.out.println("String are not Equal");
       
    }
}

20.Write a program to check strings are equalIgnoreCase.

	
class EqualsIgnoreCase {
    public static void main(String[] args) {
        String str1="apple";
        String str2="apple";
        String str3=new String("apple");
        String str4="APPlE";
        if(str1==str4)
        System.out.println("Strings are equal");
        else
        System.out.println("String are not Equal");
        
        if(str1.equalsIgnoreCase(str4))
        System.out.println("Strings are equal");
        else
        System.out.println("String are not Equal");
        
        if(str1.equalsIgnoreCase(str3))
        System.out.println("Strings are equal");
        else
        System.out.println("String are not Equal");
       
    }
}