Java: Move all lower case letters to the front, keeping the order of all the letters of a given word

Last update on May 24 2025 12:59:30 (UTC/GMT +8 hours)

23. Move Lowercase to Front

Write a Java program to move all lower case letters to the front of a given word. This will keep the relative position of all the letters (both upper and lower case) same.

Sample Solution-1:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	    String text = "Java";
		System.out.println("Original String: "+text);
		System.out.println("Move all lower case letters to the front of the said word: "+validate(text));
		text = "JavaScript";
		System.out.println("\nOriginal String: "+text);
		System.out.println("Move all lower case letters to the front of the said word: "+validate(text));
		text = "SQLite";
		System.out.println("\nOriginal String: "+text);
		System.out.println("Move all lower case letters to the front of the said word: "+validate(text));		
	}

   public static String validate(String text) {
        return text.replaceAll("[A-Z]", "") + text.replaceAll("[a-z]", "");
   }
}

Sample Output:

Original String: Java
Move all lower case letters to the front of the said word: avaJ

Original String: JavaScript
Move all lower case letters to the front of the said word: avacriptJS

Original String: SQLite
Move all lower case letters to the front of the said word: iteSQL

Pictorial Presentation:

Flowchart :

Sample Solution-2:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	    String text = "Java";
		System.out.println("Original String: "+text);
		System.out.println("Move all lower case letters to the front of the said word: "+validate(text));
		text = "JavaScript";
		System.out.println("\nOriginal String: "+text);
		System.out.println("Move all lower case letters to the front of the said word: "+validate(text));
		text = "SQLite";
		System.out.println("\nOriginal String: "+text);
		System.out.println("Move all lower case letters to the front of the said word: "+validate(text));		
	}

   public static String validate(String text) {
        String upper_ch = "",lower_ch = "";
        for(char ch : text.toCharArray())
			if(Character.isLowerCase(ch))
				lower_ch+=ch;
			else 
				upper_ch+= ch;
        return lower_ch + upper_ch;
   }
}

Sample Output:

Original String: Java
Move all lower case letters to the front of the said word: avaJ

Original String: JavaScript
Move all lower case letters to the front of the said word: avacriptJS

Original String: SQLite
Move all lower case letters to the front of the said word: iteSQL

Flowchart :

For more Practice: Solve these Related Problems:

• Write a Java program to rearrange a string so that all lowercase letters appear before uppercase letters while preserving their relative order.
• Write a Java program to implement a method that partitions a string into lowercase and uppercase segments and then concatenates them.
• Write a Java program to separate the characters of a string into lowercase and non-lowercase groups and merge them accordingly.
• Write a Java program to reorder a string by moving all lowercase characters to the front and keeping the order of all letters unchanged.

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