4 Threads can log by pressing the relevant button

app/src/main/java/com/ploedige/threadtest/MainActivity.java

@@ -4,17 +4,37 @@ import androidx.appcompat.app.AppCompatActivity;
 
 import android.os.Bundle;
 import android.util.Log;
+import android.view.View;
+import android.widget.Button;
 
 public class MainActivity extends AppCompatActivity {
 
+    TestThread[] threadArray = new TestThread[4];
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
-        TestThread testThread = new TestThread();
+        for(int i=0; i<threadArray.length;i++){
-        testThread.start();
+            threadArray[i]=new TestThread();
+            threadArray[i].setName("Thread_"+i);
+            threadArray[i].start();
+        }
 
-        Log.v("test","test");
+        //connect Buttons to Threads
+        Button button1 = findViewById(R.id.Thread1_btn);
+        Button button2 = findViewById(R.id.Thread2_btn);
+        Button button3 = findViewById(R.id.Thread3_btn);
+        Button button4 = findViewById(R.id.Thread4_btn);
+
+        button1.setOnClickListener(v ->
+                Log.v("Thread_1", String.valueOf(threadArray[0].getCounter())));
+        button2.setOnClickListener(v ->
+                Log.v("Thread_2", String.valueOf(threadArray[1].getCounter())));
+        button3.setOnClickListener(v ->
+                Log.v("Thread_3", String.valueOf(threadArray[2].getCounter())));
+        button4.setOnClickListener(v ->
+                Log.v("Thread_4", String.valueOf(threadArray[3].getCounter())));
     }
 }

app/src/main/java/com/ploedige/threadtest/TestThread.java

@@ -1,12 +1,12 @@
 package com.ploedige.threadtest;
 
-import android.util.Log;
-
 public class TestThread extends Thread{
+    private int counter;
+
     public void run() {
         while (true){
             for(int i =1; i<=20; i++){
-                Log.v("TestThread", String.valueOf(i));
+                counter = i;
                 try {
                     this.sleep(250);
                 } catch (InterruptedException e) {
@@ -15,4 +15,6 @@ public class TestThread extends Thread{
             }
         }
     }
+
+    public int getCounter(){return counter;}
 }

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

@@ -6,13 +6,48 @@
     android:layout_height="match_parent"
     tools:context=".MainActivity">
 
-    <TextView
+    <Button
+        android:id="@+id/Thread1_btn"
+        android:text="Thread 1"
+
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:text="Hello World!"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/Thread2_btn"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"/>
+
+    <Button
+        android:id="@+id/Thread2_btn"
+        android:text="Thread 2"
+
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        app:layout_constraintTop_toBottomOf="@id/Thread1_btn"
+        app:layout_constraintBottom_toTopOf="@id/Thread3_btn"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"/>
+
+    <Button
+        android:id="@+id/Thread3_btn"
+        android:text="Thread 3"
+
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        app:layout_constraintTop_toBottomOf="@id/Thread2_btn"
+        app:layout_constraintBottom_toTopOf="@id/Thread4_btn"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"/>
+
+    <Button
+        android:id="@+id/Thread4_btn"
+        android:text="Thread 4"
+
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        app:layout_constraintTop_toBottomOf="@id/Thread3_btn"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintLeft_toLeftOf="parent"
-        app:layout_constraintRight_toRightOf="parent"
+        app:layout_constraintRight_toRightOf="parent"/>
-        app:layout_constraintTop_toTopOf="parent" />
 
 </androidx.constraintlayout.widget.ConstraintLayout>