Strings

src/main/java/com/amigoscode/_2_developers/_6_strings/StringMethods.java

@@ -2,7 +2,6 @@
 
 /**
  * String Methods Exercises
- *
  * Practice the most commonly used String methods in Java. Strings are immutable
  * in Java — every method returns a NEW string rather than modifying the original.
  */
@@ -19,7 +18,10 @@ public class StringMethods {
     public static String compareEquality(String a, String b) {
         // TODO: 1 - Use equals() and equalsIgnoreCase() to compare a and b.
         //  Return a string in the format: "equals: <result>, equalsIgnoreCase: <result>"
-        return null;
+        boolean equalsValue = a.equals(b);
+        boolean equalsIgnoreCase = a.equalsIgnoreCase(b);
+
+        return "equals: " + equalsValue + ", equalsIgnoreCase: " + equalsIgnoreCase;
     }
 
     /**
@@ -33,7 +35,8 @@ public static String compareEquality(String a, String b) {
     public static String compareLexicographic(String a, String b) {
         // TODO: 2 - Use a.compareTo(b) and return:
         //  "before" if result < 0, "equal" if result == 0, "after" if result > 0.
-        return null;
+        int result = a.compareTo(b);
+        return result < 0 ? "before" : result == 0 ? "equal" : "after";
     }
 
     /**
@@ -48,7 +51,9 @@ public static String searchString(String text, String keyword) {
         // TODO: 3 - Use contains() to check if text contains keyword.
         //  Use indexOf() to find the position of keyword in text.
         //  Return "contains: <bool>, indexOf: <index>"
-        return null;
+        boolean hasText = text.contains(keyword);
+        int keywordPosition = text.indexOf(keyword);
+        return "contains: " + hasText + ", indexOf: " + keywordPosition;
     }
 
     /**
@@ -64,7 +69,8 @@ public static String replaceDemo(String text, String oldWord, String newWord) {
         // TODO: 4 - First use replace(oldWord, newWord) to swap words.
         //  Then use replaceAll("\\d", "#") to replace all digits with "#".
         //  Return the final result.
-        return null;
+        String newString = text.replace(oldWord, newWord);
+        return newString.replaceAll("\\d", "#");
     }
 
     /**
@@ -79,7 +85,12 @@ public static String splitDemo(String text, String delimiter) {
         // TODO: 5 - Use text.split(delimiter) to get an array of parts.
         //  Build a result string with each part on a new line: "[i] part"
         //  Example: "[0] apple\n[1] banana\n[2] cherry"
-        return null;
+        String[] splitText = text.split(delimiter);
+        String resultString = "";
+        for (int i = 0; i < splitText.length; i++) {
+            resultString = resultString + " [" + i + "] " + splitText[i] + "\n";
+        }
+        return resultString;
     }
 
     /**
@@ -93,7 +104,9 @@ public static String splitDemo(String text, String delimiter) {
     public static String checkStartEnd(String filename, String prefix, String extension) {
         // TODO: 6 - Use startsWith(prefix) and endsWith(extension).
         //  Return: "startsWith '<prefix>': <bool>, endsWith '<extension>': <bool>"
-        return null;
+        boolean hasPrefix = filename.startsWith(prefix);
+        boolean hasExtension = filename.endsWith(extension);
+        return "startsWith '<" + prefix + ">': <" + hasPrefix + ">, endsWith '<" + extension + ">': <" + hasExtension + ">" ;
     }
 
     /**
@@ -107,7 +120,7 @@ public static String checkStartEnd(String filename, String prefix, String extens
     public static String substringDemo(String text, int beginIndex, int endIndex) {
         // TODO: 7 - Use text.substring(beginIndex, endIndex) to extract a portion of text.
         //  Return the substring.
-        return null;
+        return text.substring(beginIndex, endIndex);
     }
 
     /**
@@ -122,7 +135,7 @@ public static String substringDemo(String text, int beginIndex, int endIndex) {
     public static String formatReceipt(String item, int quantity, double price) {
         // TODO: 8 - Use String.format() to create a formatted string.
         //  Format: "%-15s x%-5d $%.2f" (left-align item in 15 chars, quantity in 5, price with 2 decimals)
-        return null;
+        return String.format("%-15s x%-5d $%.2f", item, quantity, price);
     }
 
     public static void main(String[] args) {