Login Bindings

Login Bindings demonstrates how we can use Data Binding for callbacks from a Login Form

How to Use

Enable Data Binding in your app build.gradle

dataBinding {
    enabled = true
}

ViewModel

A ViewModel should extend BaseObservable for the mechanism to be reactive. Use notifyPropertyChanged to get callbacks for email and password fields and hence manipulate the login button. Here is how the LoginModel should look like.

public class LoginModel extends BaseObservable {

    private String email;
    private String password;
    private boolean loginEnabled;

    @Bindable
    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
        notifyPropertyChanged(BR.email);
        setLoginEnabled(isEmailAndPasswordSet());
    }

    @Bindable
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
        notifyPropertyChanged(BR.password);
        setLoginEnabled(isEmailAndPasswordSet());
    }

    @Bindable
    public boolean isLoginEnabled() {
        return loginEnabled;
    }

    public void setLoginEnabled(boolean loginEnabled) {
        this.loginEnabled = loginEnabled;
        notifyPropertyChanged(BR.loginEnabled);
    }

    /**
     * checks if email and password fields are set
     *
     * @return isEmailAndPasswordSet
     */
    private boolean isEmailAndPasswordSet() {
        return !TextUtils.isEmpty(getEmail()) && !TextUtils.isEmpty(getPassword());
    }
}

In your activity, bind the ViewModel with the view as follows:

ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);

binding.setModel(new LoginModel());

Reference

• Data Binding Library