Java Program to Convert Uppercase to Lowercase

Write a Java Program to Convert Uppercase to Lowercase with an example. In this section, we use built-in functions, loops, ASCII values to get the result. In this Java Uppercase to Lowercase example, we use the built-in function toLowerCase() on the given string.

import java.util.Scanner;

public class UpperToLower1 {
	private static Scanner sc;
	public static void main(String[] args) {
		String uppStr;
		
		sc= new Scanner(System.in);

		System.out.print("\nEnter Uppercase String to convert =  ");
		uppStr = sc.nextLine();
	
		String uppStr2 = uppStr.toLowerCase();	
		System.out.println("\nThe Lowercase String  =  " + uppStr2);
	}
}

Here, in this Convert Uppercase to Lowercase example, first, we converted the uppStr string to upch character array using the toCharArray(). 

Next, we used a For loop to iterate the upch character array from start to end. Within the loop, we check whether the character at index position greater than or equal to A & less than or equal Z. If it is True, we add 32 to the existing ASCII value. For example, A = 65, when we add 32, it becomes 97, and the ASCII value of a = 97.

import java.util.Scanner;

public class UpperToLower2 {
	private static Scanner sc;
	public static void main(String[] args) {
		String uppStr;
		int i;
		
		sc= new Scanner(System.in);

		System.out.print("\nPlease Enter Uppercase String =  ");
		uppStr = sc.nextLine();
		
		char[] upch = uppStr.toCharArray();
		
		for(i = 0; i < upch.length; i++)
		{
			if(upch[i] >= 'A' && upch[i] <= 'Z') {
				upch[i] = (char) ((int)upch[i] + 32);;
			}
		}
		System.out.print("\nThe Lowercase String  =  ");
		for(i = 0; i < upch.length; i++) {
			System.out.print(upch[i]);
		}
	}
}

Java Program to Convert Uppercase to Lowercase Example 3

Here, we haven’t changed the uppStr string to char array. Next, we used the charAt function on the uppStr to get the character at the index position. Then, we assigned each character to lowStr2.

import java.util.Scanner;

public class UpperToLower3 {
	private static Scanner sc;
	public static void main(String[] args) {
		String uppStr, lowStr2 = "";
		int i;
		
		sc= new Scanner(System.in);

		System.out.print("\nEnter Uppercase String to convert =  ");
		uppStr = sc.nextLine();
		
		char ch;
		
		for(i = 0; i < uppStr.length(); i++)
		{
			if(uppStr.charAt(i) >= 'A' && uppStr.charAt(i) <= 'Z') {
				ch = (char) (uppStr.charAt(i) + 32);
			}
			else {
				ch = (char) (uppStr.charAt(i));
			}
			lowStr2 += ch;
		}
		System.out.print("\nThe Lowercase String  =  " + lowStr2);
	}
}

In this Java Uppercase to Lowercase example, instead of assigning it to a new string, we print each character within the loop.

import java.util.Scanner;

public class UpperToLower4 {
	private static Scanner sc;
	public static void main(String[] args) {
		String uppStr;
		int i;
		
		sc= new Scanner(System.in);

		System.out.print("\nEnter Uppercase String to convert =  ");
		uppStr = sc.nextLine();
	
		System.out.print("\nThe Lowercase String =  ");
		for(i = 0; i < uppStr.length(); i++)
		{
			char ch = uppStr.charAt(i);
			if(ch >= 'A' && ch <= 'Z') {
				ch = (char) (ch + 32);
			}
			System.out.print(ch); // Str2 += ch;
		}
	}
}

This Java Program to Convert Uppercase to Lowercase using ASCII Values, we compare the ASCII values instead of comparing characters.

import java.util.Scanner;

public class UpperToLower5 {
	private static Scanner sc;
	public static void main(String[] args) {
		String uppStr1, lowStr2 = "";
		int i;
		
		sc= new Scanner(System.in);

		System.out.print("\nEnter Uppercase String to convert =  ");
		uppStr1 = sc.nextLine();
	
		for(i = 0; i < uppStr1.length(); i++)
		{
			char ch = uppStr1.charAt(i);
			if(ch >= 65 && ch <= 90) {
				ch = (char) (ch + 32);
			}
			lowStr2 += ch;
		}
		System.out.print("\nThe Lowercase String =  " + lowStr2);
	}
}

This Java code for Uppercase to Lowercase, we separated the logic using functions.

import java.util.Scanner;

public class UpperToLower6 {
	private static Scanner sc;
	public static void main(String[] args) {
		String uppStr, lowStr2;
		
		sc= new Scanner(System.in);

		System.out.print("\nEnter Uppercase String to convert =  ");
		uppStr = sc.nextLine();
		
		lowStr2 = toUpper(uppStr);
		System.out.print("\nThe Lowercase String =  " + lowStr2);
	}
	
	public static String toUpper(String uppStr) {
		String lowStr2 = "";
		
		for(int i = 0; i < uppStr.length(); i++)
		{
			char ch = uppStr.charAt(i);
			if(ch >= 65 && ch <= 90) {
				ch = (char) (ch + 32);
			}
			lowStr2 += ch;
		}
		return lowStr2;
	}
}