the xml layout and Java code for our app

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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="com.example.yitzi.myapplication.MainActivity">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
        android:src="@drawable/group"/>

    <TextView
        android:id="@+id/topTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:padding="20dp"
        android:text="top text"
        android:textColor="@android:color/black"
        android:textSize="36sp"
        android:visibility="gone"/>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:onClick="createMeme"
        android:text="CREATE MEME"/>

    <TextView
        android:id="@+id/bottomTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:padding="20dp"
        android:text="bottom text"
        android:textColor="@android:color/white"
        android:textSize="36sp"
        android:visibility="gone"/>

    <EditText
        android:id="@+id/topEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:gravity="center"
        android:hint="Write top text here!"
        android:inputType="text"
        android:paddingLeft="5dp"
        android:textColorHint="@android:color/black"/>

    <EditText
        android:id="@+id/bottomEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:gravity="center"
        android:hint="Write bottom text here!"
        android:inputType="text"
        android:paddingLeft="5dp"
        android:textColor="@android:color/white"
        android:textColorHint="@android:color/white"/>
</RelativeLayout>

MainAtivity.java

package com.example.yitzi.myapplication;

import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    TextView topTextView;
    TextView bottomTextView;
    EditText topEditText;
    TextView bottomEditText;
    Button button;
    boolean memeShown = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        topTextView = findViewById(R.id.topTextView);
        bottomTextView = findViewById(R.id.bottomTextView);
        topEditText = findViewById(R.id.topEditText);
        bottomEditText = findViewById(R.id.bottomEditText);
        button = findViewById(R.id.button);
    }

    public void createMeme(View view) {
        hideKeyboard(view);
        hideTheEditTextViewsAndTheButton(view);
        getTheTextFromTheEditTextViewsAndSetItOnTheTextViews();
        showTheTextViews();
        memeShown = true;
    }

    private void showTheTextViews() {
        toggleTextViews(View.VISIBLE);
    }

    private void getTheTextFromTheEditTextViewsAndSetItOnTheTextViews() {
        String topTextContent = topEditText.getText().toString();
        topTextView.setText(topTextContent);
        String bottomTextContent = bottomEditText.getText().toString();
        bottomTextView.setText(bottomTextContent);
    }

    private void hideTheEditTextViewsAndTheButton(View view) {
        view.setVisibility(View.GONE);
        topEditText.setVisibility(View.GONE);
        bottomEditText.setVisibility(View.GONE);
    }

    private void hideKeyboard(View view) {
        View currentFocus = this.getCurrentFocus();
        if (currentFocus != null) {
            InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
        }
    }

    @Override
    public void onBackPressed() {
        if (memeShown) {
            clearAllTextFromAllViews();
            toggleTextViews(View.GONE);
            showMemeCreationView();
            memeShown = false;
        }
        else {
            super.onBackPressed();
        }
    }

    private void showMemeCreationView() {
        topEditText.setVisibility(View.VISIBLE);
        bottomEditText.setVisibility(View.VISIBLE);
        button.setVisibility(View.VISIBLE);
    }

    private void toggleTextViews(int visibility) {
        topTextView.setVisibility(visibility);
        bottomTextView.setVisibility(visibility);
    }

    private void clearAllTextFromAllViews() {
        topTextView.setText("");
        bottomTextView.setText("");
        topEditText.setText("");
        bottomEditText.setText("");
    }
}