Okay, let's adapt the concept for an Android application using Android Studio. We'll create separate Activities to display the lists of employees and projects using `RecyclerView`. This setup involves several components: 1. **Model Classes:** `Employee.java`, `Project.java` (similar to before, potentially implementing `Parcelable` for easier data passing, though we'll pass IDs for simplicity here). 2. **Repository Classes:** Singletons to manage the in-memory data (`EmployeeRepository.java`, `ProjectRepository.java`). In a real app, this would interact with a database (like Room). 3. **RecyclerView Adapters:** To display the lists (`EmployeeAdapter.java`, `ProjectAdapter.java`). 4. **Layout Files:** For the activities and list items (`activity_employee_list.xml`, `list_item_employee.xml`, `activity_project_list.xml`, `list_item_project.xml`). 5. **Activity Classes:** `EmployeeListActivity.java`, `ProjectListActivity.java`. 6. **Placeholder Detail Activities:** `EmployeeDetailActivity.java`, `ProjectDetailActivity.java` (needed for navigation intents, implementation can be basic initially). 7. **MainActivity:** To navigate to the list activities. 8. **AndroidManifest.xml:** To declare all activities. Here's the code structure: package com.example.collaborationapp.model; import java.io.Serializable; // Using Serializable for simplicity, Parcelable is preferred for performance public class Employee implements Serializable { private int id; private String name; private String role; // Default constructor needed for some frameworks/serialization public Employee() {} public Employee(int id, String name, String role) { this.id = id; this.name = name; this.role = role; } // Getters public int getId() { return id; } public String getName() { return name; } public String getRole() { return role; } // Setters public void setId(int id) { this.id = id; } public void setName(String name) { this.name = name; } public void setRole(String role) { this.role = role; } @Override public String toString() { return "Employee [ID=" + id + ", Name=" + name + ", Role=" + role + "]"; } // Optional: equals and hashCode for list operations @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Employee employee = (Employee) o; return id == employee.id; } @Override public int hashCode() { return Integer.hashCode(id); } } package com.example.collaborationapp.model; import java.io.Serializable; import java.util.ArrayList; import java.util.List; import java.util.stream.Collectors; public class Project implements Serializable { private int id; private String name; private String description; private List assignedEmployeeIds; public Project() {} public Project(int id, String name, String description) { this.id = id; this.name = name; this.description = description; this.assignedEmployeeIds = new ArrayList<>(); } // Getters public int getId() { return id; } public String getName() { return name; } public String getDescription() { return description; } public List getAssignedEmployeeIds() { // Return a copy to prevent external modification return new ArrayList<>(assignedEmployeeIds); } // Setters public void setId(int id) { this.id = id; } public void setName(String name) { this.name = name; } public void setDescription(String description) { this.description = description; } public void setAssignedEmployeeIds(List assignedEmployeeIds) { this.assignedEmployeeIds = new ArrayList<>(assignedEmployeeIds); // Store a copy } // Association management public void assignEmployee(int employeeId) { if (!assignedEmployeeIds.contains(employeeId)) { assignedEmployeeIds.add(employeeId); } } public void removeEmployee(int employeeId) { assignedEmployeeIds.remove(Integer.valueOf(employeeId)); } @Override public String toString() { String employeeIdsStr = assignedEmployeeIds.stream() .map(String::valueOf) .collect(Collectors.joining(", ")); return "Project [ID=" + id + ", Name=" + name + ", Assigned IDs=[" + (employeeIdsStr.isEmpty() ? "None" : employeeIdsStr) + "]]"; } // Optional: equals and hashCode @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Project project = (Project) o; return id == project.id; } @Override public int hashCode() { return Integer.hashCode(id); } } package com.example.collaborationapp.repository; import com.example.collaborationapp.model.Employee; import java.util.ArrayList; import java.util.List; import java.util.Optional; import java.util.concurrent.atomic.AtomicInteger; // Singleton Repository for managing Employee data (in-memory) public class EmployeeRepository { private static volatile EmployeeRepository instance; private final List employees = new ArrayList<>(); private final AtomicInteger nextId = new AtomicInteger(1); // Thread-safe ID generation private EmployeeRepository() { // Add some initial sample data addEmployee(new Employee(nextId.getAndIncrement(), "Alice Smith", "Developer")); addEmployee(new Employee(nextId.getAndIncrement(), "Bob Johnson", "Project Manager")); addEmployee(new Employee(nextId.getAndIncrement(), "Charlie Brown", "QA Tester")); } public static EmployeeRepository getInstance() { if (instance == null) { synchronized (EmployeeRepository.class) { if (instance == null) { instance = new EmployeeRepository(); } } } return instance; } public List getAllEmployees() { // Return a copy to prevent modification of the internal list return new ArrayList<>(employees); } public Optional getEmployeeById(int id) { return employees.stream() .filter(e -> e.getId() == id) .findFirst(); } public Employee addEmployee(Employee employee) { // Ensure the employee has a valid ID (assign one if new) if (employee.getId() <= 0) { employee.setId(nextId.getAndIncrement()); } else { // If ID exists, ensure nextId is higher nextId.set(Math.max(nextId.get(), employee.getId() + 1)); // Check for duplicates before adding employees.removeIf(e -> e.getId() == employee.getId()); } employees.add(employee); return employee; // Return the employee with potentially updated ID } public Employee createEmployee(String name, String role) { Employee newEmployee = new Employee(nextId.getAndIncrement(), name, role); employees.add(newEmployee); return newEmployee; } public boolean updateEmployee(Employee updatedEmployee) { Optional existingOpt = getEmployeeById(updatedEmployee.getId()); if (existingOpt.isPresent()) { Employee existing = existingOpt.get(); existing.setName(updatedEmployee.getName()); existing.setRole(updatedEmployee.getRole()); return true; } return false; // Employee not found } public boolean deleteEmployee(int id) { boolean removed = employees.removeIf(e -> e.getId() == id); if(removed) { // Also remove this employee from any project assignments ProjectRepository.getInstance().removeEmployeeFromAllProjects(id); } return removed; } } package com.example.collaborationapp.repository; import com.example.collaborationapp.model.Project; import java.util.ArrayList; import java.util.List; import java.util.Optional; import java.util.concurrent.atomic.AtomicInteger; // Singleton Repository for managing Project data (in-memory) public class ProjectRepository { private static volatile ProjectRepository instance; private final List projects = new ArrayList<>(); private final AtomicInteger nextId = new AtomicInteger(1); private ProjectRepository() { // Add some initial sample data Project p1 = new Project(nextId.getAndIncrement(), "Website Redesign", "Update company website look and feel."); p1.assignEmployee(1); // Assign Alice addProject(p1); Project p2 = new Project(nextId.getAndIncrement(), "Mobile App Launch", "Develop and launch native mobile apps."); p2.assignEmployee(1); // Assign Alice p2.assignEmployee(2); // Assign Bob addProject(p2); } public static ProjectRepository getInstance() { if (instance == null) { synchronized (ProjectRepository.class) { if (instance == null) { instance = new ProjectRepository(); } } } return instance; } public List getAllProjects() { return new ArrayList<>(projects); // Return a copy } public Optional getProjectById(int id) { return projects.stream() .filter(p -> p.getId() == id) .findFirst(); } public Project addProject(Project project) { if (project.getId() <= 0) { project.setId(nextId.getAndIncrement()); } else { nextId.set(Math.max(nextId.get(), project.getId() + 1)); projects.removeIf(p -> p.getId() == project.getId()); // Remove potential duplicate ID before adding } projects.add(project); return project; } public Project createProject(String name, String description) { Project newProject = new Project(nextId.getAndIncrement(), name, description); projects.add(newProject); return newProject; } public boolean updateProject(Project updatedProject) { Optional existingOpt = getProjectById(updatedProject.getId()); if (existingOpt.isPresent()) { Project existing = existingOpt.get(); existing.setName(updatedProject.getName()); existing.setDescription(updatedProject.getDescription()); // Be careful about overwriting assignments if not intended // existing.setAssignedEmployeeIds(updatedProject.getAssignedEmployeeIds()); return true; } return false; } public boolean assignEmployeeToProject(int projectId, int employeeId) { Optional projectOpt = getProjectById(projectId); if (projectOpt.isPresent()) { // Optional: Check if employee exists in EmployeeRepository if (EmployeeRepository.getInstance().getEmployeeById(employeeId).isPresent()) { projectOpt.get().assignEmployee(employeeId); return true; } } return false; } public boolean removeEmployeeFromProject(int projectId, int employeeId) { Optional projectOpt = getProjectById(projectId); if (projectOpt.isPresent()) { projectOpt.get().removeEmployee(employeeId); return true; // Indicate removal attempt (doesn't mean it was present) } return false; } // Called when an employee is deleted public void removeEmployeeFromAllProjects(int employeeId) { projects.forEach(p -> p.removeEmployee(employeeId)); } public boolean deleteProject(int id) { return projects.removeIf(p -> p.getId() == id); } } package com.example.collaborationapp.adapter; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; import androidx.annotation.NonNull; import androidx.recyclerview.widget.RecyclerView; import com.example.collaborationapp.R; import com.example.collaborationapp.model.Employee; import java.util.ArrayList; import java.util.List; public class EmployeeAdapter extends RecyclerView.Adapter { private List employees = new ArrayList<>(); private OnEmployeeClickListener listener; public interface OnEmployeeClickListener { void onEmployeeClick(Employee employee); // Add methods for edit/delete if needed directly on the item // void onEditClick(Employee employee); // void onDeleteClick(Employee employee); } public EmployeeAdapter(OnEmployeeClickListener listener) { this.listener = listener; } public void setEmployees(List employees) { this.employees = employees; notifyDataSetChanged(); // In real apps, use DiffUtil for better performance } @NonNull @Override public EmployeeViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { View itemView = LayoutInflater.from(parent.getContext()) .inflate(R.layout.list_item_employee, parent, false); return new EmployeeViewHolder(itemView); } @Override public void onBindViewHolder(@NonNull EmployeeViewHolder holder, int position) { Employee currentEmployee = employees.get(position); holder.bind(currentEmployee, listener); } @Override public int getItemCount() { return employees.size(); } static class EmployeeViewHolder extends RecyclerView.ViewHolder { private TextView textViewName; private TextView textViewRole; public EmployeeViewHolder(@NonNull View itemView) { super(itemView); textViewName = itemView.findViewById(R.id.tv_employee_name); textViewRole = itemView.findViewById(R.id.tv_employee_role); } public void bind(final Employee employee, final OnEmployeeClickListener listener) { textViewName.setText(employee.getName()); textViewRole.setText(employee.getRole()); itemView.setOnClickListener(v -> { if (listener != null) { listener.onEmployeeClick(employee); } }); // Add long click listeners or specific buttons for edit/delete here } } } package com.example.collaborationapp.activity; import android.content.Intent; import android.os.Bundle; import android.widget.Toast; import androidx.activity.result.ActivityResultLauncher; import androidx.activity.result.contract.ActivityResultContracts; import androidx.appcompat.app.AppCompatActivity; import androidx.recyclerview.widget.DividerItemDecoration; import androidx.recyclerview.widget.LinearLayoutManager; import androidx.recyclerview.widget.RecyclerView; import com.example.collaborationapp.R; import com.example.collaborationapp.adapter.EmployeeAdapter; import com.example.collaborationapp.model.Employee; import com.example.collaborationapp.repository.EmployeeRepository; import com.google.android.material.floatingactionbutton.FloatingActionButton; import java.util.List; public class EmployeeListActivity extends AppCompatActivity { private RecyclerView recyclerViewEmployees; private EmployeeAdapter employeeAdapter; private EmployeeRepository employeeRepository; // Modern way to handle activity results private final ActivityResultLauncher employeeDetailLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> { // Check if the result indicates data might have changed (e.g., OK result) if (result.getResultCode() == RESULT_OK) { // Data might have been added or updated, refresh the list loadEmployees(); } // Handle other result codes if needed (e.g., deletion) // else if (result.getResultCode() == EmployeeDetailActivity.RESULT_DELETED) { loadEmployees(); } }); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_employee_list); if (getSupportActionBar() != null) { getSupportActionBar().setTitle("Employees"); getSupportActionBar().setDisplayHomeAsUpEnabled(true); // Show back button } employeeRepository = EmployeeRepository.getInstance(); recyclerViewEmployees = findViewById(R.id.rv_employees); FloatingActionButton fabAddEmployee = findViewById(R.id.fab_add_employee); setupRecyclerView(); loadEmployees(); fabAddEmployee.setOnClickListener(view -> { // Launch EmployeeDetailActivity to add a new employee Intent intent = new Intent(EmployeeListActivity.this, EmployeeDetailActivity.class); // No need to pass an ID for creation employeeDetailLauncher.launch(intent); }); } private void setupRecyclerView() { recyclerViewEmployees.setLayoutManager(new LinearLayoutManager(this)); recyclerViewEmployees.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL)); // Optional divider employeeAdapter = new EmployeeAdapter(employee -> { // Handle item click: Launch EmployeeDetailActivity to view/edit Intent intent = new Intent(EmployeeListActivity.this, EmployeeDetailActivity.class); intent.putExtra(EmployeeDetailActivity.EXTRA_EMPLOYEE_ID, employee.getId()); employeeDetailLauncher.launch(intent); }); recyclerViewEmployees.setAdapter(employeeAdapter); } private void loadEmployees() { List employees = employeeRepository.getAllEmployees(); employeeAdapter.setEmployees(employees); if (employees.isEmpty()) { Toast.makeText(this, "No employees found.", Toast.LENGTH_SHORT).show(); } } // Handle the back button in the ActionBar @Override public boolean onSupportNavigateUp() { onBackPressed(); // Default behavior for back button return true; } // Refresh list when returning to the activity @Override protected void onResume() { super.onResume(); // Reload data in case changes were made in the detail view // This is a simple way; more complex apps might use LiveData or other patterns loadEmployees(); } } package com.example.collaborationapp.adapter; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; import androidx.annotation.NonNull; import androidx.recyclerview.widget.RecyclerView; import com.example.collaborationapp.R; import com.example.collaborationapp.model.Project; import java.util.ArrayList; import java.util.List; public class ProjectAdapter extends RecyclerView.Adapter { private List projects = new ArrayList<>(); private OnProjectClickListener listener; public interface OnProjectClickListener { void onProjectClick(Project project); } public ProjectAdapter(OnProjectClickListener listener) { this.listener = listener; } public void setProjects(List projects) { this.projects = projects; notifyDataSetChanged(); // Use DiffUtil in real apps } @NonNull @Override public ProjectViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { View itemView = LayoutInflater.from(parent.getContext()) .inflate(R.layout.list_item_project, parent, false); return new ProjectViewHolder(itemView); } @Override public void onBindViewHolder(@NonNull ProjectViewHolder holder, int position) { Project currentProject = projects.get(position); holder.bind(currentProject, listener); } @Override public int getItemCount() { return projects.size(); } static class ProjectViewHolder extends RecyclerView.ViewHolder { private TextView textViewName; private TextView textViewDescription; public ProjectViewHolder(@NonNull View itemView) { super(itemView); textViewName = itemView.findViewById(R.id.tv_project_name); textViewDescription = itemView.findViewById(R.id.tv_project_description); } public void bind(final Project project, final OnProjectClickListener listener) { textViewName.setText(project.getName()); textViewDescription.setText(project.getDescription()); itemView.setOnClickListener(v -> { if (listener != null) { listener.onProjectClick(project); } }); } } } package com.example.collaborationapp.activity; import android.content.Intent; import android.os.Bundle; import android.widget.Toast; import androidx.activity.result.ActivityResultLauncher; import androidx.activity.result.contract.ActivityResultContracts; import androidx.appcompat.app.AppCompatActivity; import androidx.recyclerview.widget.DividerItemDecoration; import androidx.recyclerview.widget.LinearLayoutManager; import androidx.recyclerview.widget.RecyclerView; import com.example.collaborationapp.R; import com.example.collaborationapp.adapter.ProjectAdapter; import com.example.collaborationapp.model.Project; import com.example.collaborationapp.repository.ProjectRepository; import com.google.android.material.floatingactionbutton.FloatingActionButton; import java.util.List; public class ProjectListActivity extends AppCompatActivity { private RecyclerView recyclerViewProjects; private ProjectAdapter projectAdapter; private ProjectRepository projectRepository; private final ActivityResultLauncher projectDetailLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> { if (result.getResultCode() == RESULT_OK) { loadProjects(); // Refresh list on return if data changed } }); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_project_list); if (getSupportActionBar() != null) { getSupportActionBar().setTitle("Projects"); getSupportActionBar().setDisplayHomeAsUpEnabled(true); } projectRepository = ProjectRepository.getInstance(); recyclerViewProjects = findViewById(R.id.rv_projects); FloatingActionButton fabAddProject = findViewById(R.id.fab_add_project); setupRecyclerView(); loadProjects(); fabAddProject.setOnClickListener(view -> { // Launch ProjectDetailActivity to add a new project Intent intent = new Intent(ProjectListActivity.this, ProjectDetailActivity.class); projectDetailLauncher.launch(intent); }); } private void setupRecyclerView() { recyclerViewProjects.setLayoutManager(new LinearLayoutManager(this)); recyclerViewProjects.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL)); projectAdapter = new ProjectAdapter(project -> { // Handle item click: Launch ProjectDetailActivity to view/edit Intent intent = new Intent(ProjectListActivity.this, ProjectDetailActivity.class); intent.putExtra(ProjectDetailActivity.EXTRA_PROJECT_ID, project.getId()); projectDetailLauncher.launch(intent); }); recyclerViewProjects.setAdapter(projectAdapter); } private void loadProjects() { List projects = projectRepository.getAllProjects(); projectAdapter.setProjects(projects); if (projects.isEmpty()) { Toast.makeText(this, "No projects found.", Toast.LENGTH_SHORT).show(); } } @Override public boolean onSupportNavigateUp() { onBackPressed(); return true; } @Override protected void onResume() { super.onResume(); loadProjects(); // Refresh list when returning } } package com.example.collaborationapp.activity; import android.os.Bundle; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; import androidx.appcompat.app.AppCompatActivity; import com.example.collaborationapp.R; import com.example.collaborationapp.model.Employee; import com.example.collaborationapp.repository.EmployeeRepository; import java.util.Optional; public class EmployeeDetailActivity extends AppCompatActivity { public static final String EXTRA_EMPLOYEE_ID = "com.example.collaborationapp.EXTRA_EMPLOYEE_ID"; // public static final int RESULT_DELETED = 2; // Example custom result code private EditText editTextName; private EditText editTextRole; private Button buttonSave; private Button buttonDelete; // Optional delete button private EmployeeRepository employeeRepository; private Employee currentEmployee; // Holds the employee being edited, or null if creating new @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_employee_detail); // You need to create this layout editTextName = findViewById(R.id.et_employee_name); editTextRole = findViewById(R.id.et_employee_role); buttonSave = findViewById(R.id.btn_save_employee); buttonDelete = findViewById(R.id.btn_delete_employee); // Make sure this ID exists in your layout employeeRepository = EmployeeRepository.getInstance(); int employeeId = getIntent().getIntExtra(EXTRA_EMPLOYEE_ID, -1); if (employeeId != -1) { // Editing existing employee Optional employeeOpt = employeeRepository.getEmployeeById(employeeId); if (employeeOpt.isPresent()) { currentEmployee = employeeOpt.get(); editTextName.setText(currentEmployee.getName()); editTextRole.setText(currentEmployee.getRole()); if (getSupportActionBar() != null) getSupportActionBar().setTitle("Edit Employee"); buttonDelete.setVisibility(android.view.View.VISIBLE); // Show delete button } else { // Employee not found, handle error (e.g., finish activity) Toast.makeText(this, "Employee not found", Toast.LENGTH_SHORT).show(); finish(); return; } } else { // Creating new employee if (getSupportActionBar() != null) getSupportActionBar().setTitle("Add Employee"); buttonDelete.setVisibility(android.view.View.GONE); // Hide delete button currentEmployee = null; // Explicitly null for clarity } if (getSupportActionBar() != null) { getSupportActionBar().setDisplayHomeAsUpEnabled(true); } buttonSave.setOnClickListener(v -> saveEmployee()); buttonDelete.setOnClickListener(v -> deleteEmployee()); } @Override public boolean onSupportNavigateUp() { // Handle the back button press in the action bar // You might want to ask the user if they want to discard changes here finish(); // Simply close the activity return true; } private void saveEmployee() { String name = editTextName.getText().toString().trim(); String role = editTextRole.getText().toString().trim(); if (name.isEmpty() || role.isEmpty()) { Toast.makeText(this, "Please enter name and role", Toast.LENGTH_SHORT).show(); return; } if (currentEmployee != null) { // Update existing employee currentEmployee.setName(name); currentEmployee.setRole(role); employeeRepository.updateEmployee(currentEmployee); Toast.makeText(this, "Employee updated", Toast.LENGTH_SHORT).show(); } else { // Create new employee employeeRepository.createEmployee(name, role); Toast.makeText(this, "Employee added", Toast.LENGTH_SHORT).show(); } setResult(RESULT_OK); // Indicate success to the calling activity finish(); // Close the detail activity } private void deleteEmployee() { if (currentEmployee != null) { // Add a confirmation dialog here in a real app boolean deleted = employeeRepository.deleteEmployee(currentEmployee.getId()); if (deleted) { Toast.makeText(this, "Employee deleted", Toast.LENGTH_SHORT).show(); setResult(RESULT_OK); // Or use a custom result code like RESULT_DELETED finish(); } else { Toast.makeText(this, "Error deleting employee", Toast.LENGTH_SHORT).show(); } } } }