Problem with encrypting a string using arrays

Hi, I am having trouble with a program in which I am promted to encrypt a string by using an array with the normal alphabet compared to an array with a randomly ordered alphabet. I am having trouble with the conversion. Can anyone see where I am going wrong?

Here is the class with the arrays:

import java.util.*;
public class Final 
{
	private char [] alphabet = new char [26];
	private char [] encrypt = new char [26];
	private String sentence;
	
	
	public Final()
	{
		alphabet[0] = 'a';
		alphabet[1] = 'b';
		alphabet[2] = 'c';
		alphabet[3] = 'd';
		alphabet[4] = 'e';
		alphabet[5] = 'f';
		alphabet[6] = 'g';
		alphabet[7] = 'h';
		alphabet[8] = 'i';
		alphabet[9] = 'j';
		alphabet[10] = 'k';
		alphabet[11] = 'l';
		alphabet[12] = 'm';
		alphabet[13] = 'n';
		alphabet[14] = 'o';
		alphabet[15] = 'p';
		alphabet[16] = 'q';
		alphabet[17] = 'r';
		alphabet[18] = 's';
		alphabet[19] = 't';
		alphabet[20] = 'u';
		alphabet[21] = 'v';
		alphabet[22] = 'w';
		alphabet[23] = 'x';
		alphabet[24] = 'y';
		alphabet[25] = 'z';
		
		
		final String randombet = "qwertyuioplkjhgfdsazxcvbnm";
	    final int N = randombet.length();
	    Random r = new Random();
		encrypt[0] = randombet.charAt(r.nextInt(N));
		encrypt[1] = randombet.charAt(r.nextInt(N));
		encrypt[2] = randombet.charAt(r.nextInt(N));
		encrypt[3] = randombet.charAt(r.nextInt(N));
		encrypt[4] = randombet.charAt(r.nextInt(N));
		encrypt[5] = randombet.charAt(r.nextInt(N));
		encrypt[6] = randombet.charAt(r.nextInt(N));
		encrypt[7] = randombet.charAt(r.nextInt(N));
		encrypt[8] = randombet.charAt(r.nextInt(N));
		encrypt[9] = randombet.charAt(r.nextInt(N));
		encrypt[10] = randombet.charAt(r.nextInt(N));
		encrypt[11] = randombet.charAt(r.nextInt(N));
		encrypt[12] = randombet.charAt(r.nextInt(N));
		encrypt[13] = randombet.charAt(r.nextInt(N));
		encrypt[14] = randombet.charAt(r.nextInt(N));
		encrypt[15] = randombet.charAt(r.nextInt(N));
		encrypt[16] = randombet.charAt(r.nextInt(N));
		encrypt[17] = randombet.charAt(r.nextInt(N));
		encrypt[18] = randombet.charAt(r.nextInt(N));
		encrypt[19] = randombet.charAt(r.nextInt(N));
		encrypt[20] = randombet.charAt(r.nextInt(N));
		encrypt[21] = randombet.charAt(r.nextInt(N));
		encrypt[22] = randombet.charAt(r.nextInt(N));
		encrypt[23] = randombet.charAt(r.nextInt(N));
		encrypt[24] = randombet.charAt(r.nextInt(N));
		encrypt[25] = randombet.charAt(r.nextInt(N));
		
		sentence = "This is the default sentence.";
		
	}
	
	public void randomizeEncrypt()
	{
		final String randombet = "qwertyuioplkjhgfdsazxcvbnm";
	    final int N = randombet.length();
	    Random r = new Random();
		for (int i = 0; i < 26; i++)
		{
			encrypt[i] = randombet.charAt(r.nextInt(N));
		}
		
	}
	public char [] getAlpha()
	{
		return alphabet;
	}
	public char [] getEncrypt()
	{
		return encrypt;
	}
	public String getSent()
	{
		return sentence;
	}
	public void setSent(String sent)
	{
		sentence = sent;
	}
}

Here is my client application:

import java.util.*;
public class FinalClient
{
	static Scanner scan = new Scanner(System.in);
	static Final x = new Final();
	static char [] testalphabet = new char [26];
	public static void main(String[] args) 
	{
		System.out.println("testing encrypted alphabet, in respect to a-z.");
		x.randomizeEncrypt();
		testalphabet = x.getEncrypt();
		for (int i = 0; i < 26; i++) {
			System.out.println(testalphabet[i]);
	    }
		System.out.println("Please set sentence to be encrypted.");
	    x.setSent(scan.next());
	    String oldSent = x.getSent().toLowerCase();
	    String newSent = "";
	    System.out.println("Your encrypted sentence is: \n");
	    char temp;
	    for (int i = 0; i < x.getSent().length(); i++) 
	    {
	    	for (int o = 0; o < 26; o++)
			{
	    		if (oldSent.charAt(i) != 'a' || oldSent.charAt(i) != 'b' || oldSent.charAt(i) != 'c' || oldSent.charAt(i) != 'd' || oldSent.charAt(i) != 'e' || oldSent.charAt(i) != 'f' ||
	    				oldSent.charAt(i) != 'g' || oldSent.charAt(i) != 'h' || oldSent.charAt(i) != 'i' || oldSent.charAt(i) != 'j' || oldSent.charAt(i) != 'k' || oldSent.charAt(i) != 'l' || 
	    				oldSent.charAt(i) != 'm' || oldSent.charAt(i) != 'n' || oldSent.charAt(i) != 'o' || oldSent.charAt(i) != 'p' || oldSent.charAt(i) != 'q' || oldSent.charAt(i) != 'r' || 
	    				oldSent.charAt(i) != 's' || oldSent.charAt(i) != 't' || oldSent.charAt(i) != 'u' || oldSent.charAt(i) != 'v' || oldSent.charAt(i) != 'w' || oldSent.charAt(i) != 'x' || 
	    				oldSent.charAt(i) != 'y' || oldSent.charAt(i) != 'z')
	    		{
	    			newSent += oldSent.charAt(i);
	    		}
	    		else
	    		{
	    			if (oldSent.charAt(i) == x.getAlpha()[o] )
					{
		    			temp = testalphabet[o];
						newSent += temp;
						
					}	
	    		}
	    		
				
			}
	    	
			
	    }
	    System.out.println(newSent);
	}

}

Thank you ahead of time for any helpful replies.

The problematic area is likely to be on the client section starting on line 19 onwards.