Java框架和Kotlin框架在Android开发中的互补

// Kotlin代码：处理用户输入和验证
class LoginFragment : Fragment() {
    override fun onCreateView(...) {
        val viewModel = ViewModelProviders.of(this).get(LoginViewModel::class.java)
        binding.loginButton.setOnClickListener {
            // Validating input using standard Java libraries
            if (binding.usernameInput.text.isEmpty() || binding.passwordInput.text.isEmpty()) {
                Toast.makeText(context, "Empty fields", Toast.LENGTH_SHORT).show()
            } else {
                viewModel.loginUser(binding.usernameInput.text.toString(), binding.passwordInput.text.toString())
            }
        }
    }
}

// Java代码：处理网络请求和业务逻辑
class LoginViewModel extends ViewModel {
    private val repository = LoginRepository()

    fun loginUser(username: String, password: String) {
        repository.login(username, password)
            .observeForever { result ->
                if (result.isSuccess) {
                    // Navigate to the home activity using Java APIs
                    startActivity(new Intent(context, HomeActivity::class.java))
                } else {
                    // Show an error message using Kotlin extension functions
                    context?.showToast("Login failed")
                }
            }
    }
}