Fragment

package com.example.eurynomus.fragments;

import android.graphics.Color;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.TextView;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

    TextView textView, textView2;
    FrameLayout frameLayout;
    FrameLayout frameLayout2;
    Button button;

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

        textView = findViewById(R.id.textView);
        textView2 = findViewById(R.id.textView2);
        frameLayout = findViewById(R.id.frameLayout);
        frameLayout2 = findViewById(R.id.frameLayout2);
        button = findViewById(R.id.button);


        // Generate random color
        Random rnd = new Random();
        Integer color = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
        Random rnd2 = new Random();
        Integer color2 = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));

        textView.setText( String.format("#%06X", (0xFFFFFF & color)) );
        textView2.setText( String.format("#%06X", (0xFFFFFF & color2)) );

        frameLayout.setBackgroundColor(color);
        frameLayout2.setBackgroundColor(color2);

        final Fragment fragment = (Fragment) getSupportFragmentManager().findFragmentById(R.id.fragment);
        fragment.getView().setBackgroundColor(Color.WHITE);



        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                // create a FragmentManager
                FragmentManager fm = getSupportFragmentManager();
                // create a FragmentTransaction to begin the transaction and replace the Fragment
                FragmentTransaction fragmentTransaction = fm.beginTransaction();
                // replace the FrameLayout with new Fragment
                fragmentTransaction.replace(R.id.frameLayout, fragment);
                fragmentTransaction.commit(); // save the changes
            }

        });
    }
}






<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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="horizontal"
    tools:context=".MainActivity">

    <FrameLayout
        android:id="@+id/frameLayout"
        android:layout_width="405dp"
        android:layout_height="154dp"
        android:layout_marginStart="3dp"
        android:layout_marginEnd="3dp"
        android:layout_marginBottom="136dp"
        app:layout_constraintBottom_toTopOf="@+id/frameLayout2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView"
            app:layout_constraintTop_toBottomOf="@+id/frameLayout"/>

    </FrameLayout>

    <FrameLayout
        android:id="@+id/frameLayout2"
        android:layout_width="405dp"
        android:layout_height="154dp"
        android:layout_marginTop="48dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/frameLayout">

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView"
            app:layout_constraintTop_toBottomOf="@+id/frameLayout2" />

    </FrameLayout>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="27dp"
        android:layout_marginEnd="30dp"
        android:layout_marginBottom="39dp"
        android:text="Add"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/button2"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="30dp"
        android:layout_marginEnd="22dp"
        android:layout_marginBottom="39dp"
        android:text="Transfer"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/button3"
        app:layout_constraintStart_toEndOf="@+id/button" />

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="7dp"
        android:layout_marginEnd="53dp"
        android:layout_marginBottom="39dp"
        android:text="Remove"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/button2" />

    <fragment
        android:id="@+id/fragment"
        android:layout_width="405dp"
        android:layout_height="154dp"
        android:layout_marginStart="3dp"
        android:layout_marginEnd="3dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />



</android.support.constraint.ConstraintLayout>





!!!!! FragmentOne.java !!!!!!

package com.example.eurynomus.fragments;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;

import java.util.Random;

public class FragmentOne extends Fragment {

    FrameLayout frameLayout;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.activity_main, parent, false);


    }

    Random rnd = new Random();
    Integer color = Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
}