Add Main class for Task 9: User input validation with rules

.gitignore

+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
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.idea/.gitignore

+# Default ignored files
+/shelf/
+/workspace.xml

.idea/misc.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="ms-17" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>
\ No newline at end of file

.idea/modules.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/ValidationFramework.iml" filepath="$PROJECT_DIR$/ValidationFramework.iml" />
+    </modules>
+  </component>
+</project>
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.idea/vcs.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/.." vcs="Git" />
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
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ValidationFramework.iml

+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
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src/Main.java

+public class Main {
+    public static void main(String[] args) {
+        String reddit = new String();
+        User user = new User("Anita", "reddit", "596534123");  // Invalid user
+
+        Validator<User> validator = new Validator<User>()
+                .addRule(ValidationRule.notBlank("Name", User::name))
+                .addRule(ValidationRule.notBlank("Email", User::email))
+                .addRule(ValidationRule.minLength("Password", User::password, 6));
+
+        try {
+            validator.validate(user);
+        } catch (ValidationException ve) {
+            System.out.println("Validation failed with errors:");
+            ve.getErrors().forEach(System.out::println);
+        }
+    }
+}

src/User.java

+package PACKAGE_NAME;
+
+public class User {
+}

src/ValidationException.java

+package PACKAGE_NAME;
+
+public class ValidationException {
+}

src/ValidationRule.java

+@FunctionalInterface
+public interface ValidationRule<T> {
+    String validate(T object);
+
+    // Static helper methods to define common rules
+    static <T> ValidationRule<T> notNull(String fieldName, java.util.function.Function<T, Object> getter) {
+        return object -> getter.apply(object) == null ? fieldName + " must not be null" : null;
+    }
+
+    static <T> ValidationRule<T> notBlank(String fieldName, java.util.function.Function<T, String> getter) {
+        return object -> {
+            String val = getter.apply(object);
+            return (val == null || val.trim().isEmpty()) ? fieldName + " must not be blank" : null;
+        };
+    }
+
+    static <T> ValidationRule<T> minLength(String fieldName, java.util.function.Function<T, String> getter, int min) {
+        return object -> {
+            String val = getter.apply(object);
+            return (val != null && val.length() < min) ? fieldName + " must be at least " + min + " characters" : null;
+        };
+    }
+}

src/Validator.java

+package PACKAGE_NAME;
+
+public class Validator {
+}