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| − | The following string of text has a secret code encrypted inside it. In order to decipher it, you will need to: | + | The following string of text has a secret code encrypted inside it. |
| − | 1) Extract every fourth letter of the string
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| − | 2) Reverse the order of the extracted letters
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| − | 3) Set the case of the extracted letters so that they alternate between uppercase and lowercase,
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| − | with the first letter being uppercase.
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| − |
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| − | The following is the string that must be deciphered:
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| − | | + | |
| − | xmydartlkarrsgeoptwwjvbodeblxgbleivetoihewt
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| − | | + | |
| − | To solve this problem:
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| − | You will need three string variables:
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| − | - one called "message" to store the above string to be deciphered
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| − | - one called "result1" to store the result after Step 1
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| − | - one called "secretCode" to store the results after Steps 2 and 3
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| − | | + | |
| − | To extract every fourth letter, you will need the length method, charAt() method, a while loop, a counter, and the "message" and "result1" string variables.
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| − | | + | |
| − | To reverse the order of the letters, you will need the length() and charAt() methods, a while loop, and the "result1" and "secretCode" string variables.
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| − | | + | |
| − | Note that because the first char in a string is index 0, the last char
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| − | will actually be length - 1. For example, a string with 5 chars the indexes will be from 0 to 4.
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| − | | + | |
| − | To alternate the cases, you will need the length(), charAt(), toLowerCase(), and toUpperCase() methods, a while loop, and the "secretCode" string variable.
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| − | | + | |
| − | | + | |
| − | Solution
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| − | | + | |
| − | public class DecodeMessage
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| − | {
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| − | public static void main(String[] args)
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| − | {
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| − | String message;
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| − | String result1 = "";
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| − | String password = "";
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| − | int counter = 4;
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| − |
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| − | message = "xmydartlkarrsgeoptwwjvbodeblxgbleivetoihewt";
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| − |
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| − | //extract every fourth letter
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| − | while(counter < message.length)
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| − | {
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| − | result1 += message.charAt(counter);
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| − | counter += 4;
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| − | }
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| − | | + | |
| − |
| + | |
| − | //reset counter to end of result1
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| − | counter = result1.length - 1;
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| − |
| + | |
| − | //traverse result1 from the end to the beginning and store the letters in password
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| − | while(counter >= 0)
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| − | {
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| − | password += message.charAt(counter);
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| − | counter--;
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| − | }
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| − |
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| − | //alternate the cases in result 2. Counter is now at 0 so it doesn't need to be reset
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| − | while(counter < password.length)
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| − | {
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| − | if(counter%2 == 0)
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| − | {
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| − | password.charAt(counter).toUpperCase();
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| − | }
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| − | counter++;
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| − | }
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| − | }
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| − | }
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| − | | + | |
| − | The final output (ie. the secret code) should be HeLlOwOrLd
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