Why does my emulator not show anything despite no errors being shown?

Question

I'm currently trying to figure out how to create a ListView together with a bottom navigation bar, however, though after running the emulator it did not show anything. Why is this so?

This is my activity_main.xml file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <fragment
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:id="@+id/nav_host_fragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_graph" />
    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottom_nav"
        app:menu="@menu/home"
        />
</LinearLayout>

This is my nav_graph.xml file

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/nav_graph.xml"
    app:startDestination="@id/home">

    <fragment
        android:id="@+id/home"
        android:name="sg.edu.rp.c346.a3pdwork.HomeFragment"
        android:label="fragment_home"
        tools:layout="@layout/fragment_home" />
    <fragment
        android:id="@+id/About"
        android:name="sg.edu.rp.c346.a3pdwork.AboutFragment"
        android:label="fragment_about"
        tools:layout="@layout/fragment_about" />
    <fragment
        android:id="@+id/Login"
        android:name="sg.edu.rp.c346.a3pdwork.LoginFragment"
        android:label="fragment_login"
        tools:layout="@layout/fragment_login" />
</navigation>

This is my home.xml file

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/home"
        android:title="Home"
        android:icon="@drawable/ic_action_home"
        />
    <item
        android:id="@+id/Login"
        android:title="Login"
        android:icon="@drawable/ic_action_login"
        />
    <item
        android:id="@+id/About"
        android:title="About"
        android:icon="@drawable/ic_action_about"
        />

</menu>

This is my fragment_home.xml file

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".HomeFragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment" />

    <ListView
        android:id="@+id/listViewDetails"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</FrameLayout>

This is my HomeFragment.java file

package sg.edu.rp.c346.a3pdwork;


import android.os.Bundle;

import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link Fragment} subclass.
 */
public class HomeFragment extends Fragment {


    public HomeFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_home, container, false);
    }

}

This is my fragment_login.xml file

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".LoginFragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment" />

</FrameLayout>

This is my LoginFragment.java file

package sg.edu.rp.c346.a3pdwork;


import android.os.Bundle;

import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link Fragment} subclass.
 */
public class LoginFragment extends Fragment {


    public LoginFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_login, container, false);
    }

}

This is my fragment_about.xml file

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".AboutFragment">

<!-- TODO: Update blank fragment layout -->
<TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="@string/hello_blank_fragment" />

</FrameLayout>

This is my AboutFragment.java file

package sg.edu.rp.c346.a3pdwork;


import android.os.Bundle;

import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link Fragment} subclass.
 */
public class AboutFragment extends Fragment {


    public AboutFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_about, container, false);
    }

}

This is my MainActivity.java file

package sg.edu.rp.c346.a3pdwork;

import androidx.appcompat.app.AppCompatActivity;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.NavigationUI;

import android.os.Bundle;

import com.google.android.material.bottomnavigation.BottomNavigationView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        NavController navController = Navigation.findNavController(this,
                R.id.nav_host_fragment);
        BottomNavigationView bottomNav = findViewById(R.id.bottom_nav);
      NavigationUI.setupWithNavController(bottomNav, navController);
    }
}

Answer 1

Ruchin. Wish you many good things to come with android developing.

In this situation I've got 2 things to tell you:

First: Your BottomNavigationView has no android:layout_width and android:layout_height attributes. I think you just forgot to put them in here (if so, it is not any problem, I just wanted to make sure you notice that).

Second: Your layout is shown correctly. Why you see nothing? Because you have two views TextView and ListView which have android:layout_height="match_parent" . So at first TextView is rendered and then ListView is rendered on it.

How can you see some results? That's simple. Just change FrameLayout to LinearLayout , set orientation to vertical and set TextView 's height to wrap_content . You can put these changes in your fragment_home.xml file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".HomeFragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello_blank_fragment" />

    <ListView
        android:id="@+id/listViewDetails"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>