Move ActivityThread instance

An ActivityThread instance will be needed from several classes.

server/src/main/java/com/genymobile/scrcpy/Workarounds.java

@@ -1,5 +1,7 @@
 package com.genymobile.scrcpy;
 
+import com.genymobile.scrcpy.wrappers.ActivityThread;
+
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.app.Application;
@@ -20,8 +22,7 @@ import java.lang.reflect.Method;
 
 public final class Workarounds {
 
-    private static Class<?> activityThreadClass;
+    private static boolean activityThreadFilled;
-    private static Object activityThread;
 
     private Workarounds() {
         // not instantiable
@@ -42,17 +43,16 @@ public final class Workarounds {
 
     @SuppressLint("PrivateApi,DiscouragedPrivateApi")
     private static void fillActivityThread() throws Exception {
-        if (activityThread == null) {
+        if (!activityThreadFilled) {
-            // ActivityThread activityThread = new ActivityThread();
+            Class<?> activityThreadClass = ActivityThread.getActivityThreadClass();
-            activityThreadClass = Class.forName("android.app.ActivityThread");
+            Object activityThread = ActivityThread.getActivityThread();
-            Constructor<?> activityThreadConstructor = activityThreadClass.getDeclaredConstructor();
-            activityThreadConstructor.setAccessible(true);
-            activityThread = activityThreadConstructor.newInstance();
 
             // ActivityThread.sCurrentActivityThread = activityThread;
             Field sCurrentActivityThreadField = activityThreadClass.getDeclaredField("sCurrentActivityThread");
             sCurrentActivityThreadField.setAccessible(true);
             sCurrentActivityThreadField.set(null, activityThread);
+
+            activityThreadFilled = true;
         }
     }
 
@@ -75,6 +75,9 @@ public final class Workarounds {
             appInfoField.setAccessible(true);
             appInfoField.set(appBindData, applicationInfo);
 
+            Class<?> activityThreadClass = ActivityThread.getActivityThreadClass();
+            Object activityThread = ActivityThread.getActivityThread();
+
             // activityThread.mBoundApplication = appBindData;
             Field mBoundApplicationField = activityThreadClass.getDeclaredField("mBoundApplication");
             mBoundApplicationField.setAccessible(true);
@@ -95,6 +98,9 @@ public final class Workarounds {
             baseField.setAccessible(true);
             baseField.set(app, FakeContext.get());
 
+            Class<?> activityThreadClass = ActivityThread.getActivityThreadClass();
+            Object activityThread = ActivityThread.getActivityThread();
+
             // activityThread.mInitialApplication = app;
             Field mInitialApplicationField = activityThreadClass.getDeclaredField("mInitialApplication");
             mInitialApplicationField.setAccessible(true);

server/src/main/java/com/genymobile/scrcpy/wrappers/ActivityThread.java

@@ -0,0 +1,32 @@
+package com.genymobile.scrcpy.wrappers;
+
+import java.lang.reflect.Constructor;
+
+public class ActivityThread {
+
+    private static final Class<?> activityThreadClass;
+    private static final Object activityThread;
+
+    static {
+        try {
+            activityThreadClass = Class.forName("android.app.ActivityThread");
+            Constructor<?> activityThreadConstructor = activityThreadClass.getDeclaredConstructor();
+            activityThreadConstructor.setAccessible(true);
+            activityThread = activityThreadConstructor.newInstance();
+        } catch (Exception e) {
+            throw new AssertionError(e);
+        }
+    }
+
+    private ActivityThread() {
+        // only static methods
+    }
+
+    public static Object getActivityThread() {
+        return activityThread;
+    }
+
+    public static Class<?> getActivityThreadClass() {
+        return activityThreadClass;
+    }
+}