MainActivity for the Password Strength Calculator App for Android tutorial on the SSaurel's Channel

MainActivity.java

package com.ssaurel.passwordstrength;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

  private TextView textView;
  private EditText editText;
  private View root;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    root = findViewById(R.id.root);
    textView = findViewById(R.id.textView);
    editText = findViewById(R.id.editText);
    // now we set Text Watcher on the edit text 
    // to update the password strength in real time
    editText.addTextChangedListener(new TextWatcher() {
      @Override
      public void beforeTextChanged(CharSequence s, int start, int count, int after) {
      }

      @Override
      public void onTextChanged(CharSequence s, int start, int before, int count) {
        calculatePasswordStrength(s.toString());
      }

      @Override
      public void afterTextChanged(Editable s) {
	  }
    });
  }

  private void calculatePasswordStrength(String str) {
    // Now, we need to define a PasswordStrength enum 
    // with a calculate static method returning the password strength
    PasswordStrength passwordStrength = PasswordStrength.calculate(str);
    textView.setText(passwordStrength.msg);
    root.setBackgroundColor(passwordStrength.color);
  }
}