Finished

app/src/main/AndroidManifest.xml

@@ -9,6 +9,13 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
+        <activity android:name=".DisplayMessageActivity"
+            android:parentActivityName=".MainActivity">
+            <!-- The meta-data tag is required if you support API level 15 and lower -->
+            <meta-data
+                android:name="android.support.PARENT_ACTIVITY"
+                android:value=".MainActivity" />
+        </activity>
         <activity android:name=".MainActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

app/src/main/java/com/example/zabezpieczonynotatnik/DisplayMessageActivity.java

@@ -0,0 +1,23 @@
+package com.example.zabezpieczonynotatnik;
+
+import androidx.appcompat.app.AppCompatActivity;
+import android.content.Intent;
+import android.os.Bundle;
+import android.widget.TextView;
+
+public class DisplayMessageActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_display_message);
+
+        // Get the Intent that started this activity and extract the string
+        Intent intent = getIntent();
+        String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
+
+        // Capture the layout's TextView and set the string as its text
+        TextView textView = findViewById(R.id.textView);
+        textView.setText(message);
+    }
+}

app/src/main/java/com/example/zabezpieczonynotatnik/MainActivity.java

@@ -1,12 +1,13 @@
 package com.example.zabezpieczonynotatnik;
 
 import androidx.appcompat.app.AppCompatActivity;
-
+import android.content.Intent;
 import android.os.Bundle;
 import android.view.View;
+import android.widget.EditText;
 
 public class MainActivity extends AppCompatActivity {
-
+    public static final String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -15,6 +16,10 @@ public class MainActivity extends AppCompatActivity {
 
     /** Called when the user taps the Send button */
     public void sendMessage(View view) {
-        // Do something in response to button
+        Intent intent = new Intent(this, DisplayMessageActivity.class);
+        EditText editText = (EditText) findViewById(R.id.editText);
+        String message = editText.getText().toString();
+        intent.putExtra(EXTRA_MESSAGE, message);
+        startActivity(intent);
     }
 }

app/src/main/res/layout/activity_display_message.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.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"
+    tools:context=".DisplayMessageActivity">
+
+    <TextView
+        android:id="@+id/textView"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="TextView"
+        tools:layout_editor_absoluteX="176dp"
+        tools:layout_editor_absoluteY="16dp" />
+</androidx.constraintlayout.widget.ConstraintLayout>