App-2.js

import React from "react";
import { Button, StyleSheet, Text, View } from "react-native";
import { createStackNavigator, createAppContainer } from "react-navigation";

class CitiesScreen extends React.Component {
  render() {
    return (
      <View style={styles.container}>
        <Text>Cities Screen</Text>
        <Button
          title="Go to Lists"
          onPress={() => this.props.navigation.navigate("Lists")}
        />
      </View>
    );
  }
}

class ListsScreen extends React.Component {
  render() {
    return (
      <View style={styles.container}>
        <Text>Lists Screen</Text>
        <Button
          title="Go to Entries"
          onPress={() => this.props.navigation.navigate("Entries")}
        />
      </View>
    );
  }
}

class EntriesScreen extends React.Component {
  render() {
    return (
      <View style={styles.container}>
        <Text>Entries Screen</Text>
      </View>
    );
  }
}

const AppNavigator = createStackNavigator({
  Cities: {
    screen: CitiesScreen
  },
  Lists: {
    screen: ListsScreen
  },
  Entries: {
    screen: EntriesScreen
  }
});

export default createAppContainer(AppNavigator);

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: "#fff",
    alignItems: "center",
    justifyContent: "center"
  }
});