1 /*
2  * Copyright (C) 2020 The Dagger Authors.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package dagger.hilt.android.internal;
18 
19 import android.os.Looper;
20 
21 /** Thread utility methods. */
22 public final class ThreadUtil {
23 
24   private static Thread mainThread;
25 
ThreadUtil()26   private ThreadUtil() {}
27 
28   /** Returns true if the current thread is the Main thread. */
isMainThread()29   public static boolean isMainThread() {
30     if (mainThread == null) {
31       mainThread = Looper.getMainLooper().getThread();
32     }
33     return Thread.currentThread() == mainThread;
34   }
35 
36   /** Checks that the current thread is the Main thread. Otherwise throws an exception. */
ensureMainThread()37   public static void ensureMainThread() {
38     if (!isMainThread()) {
39       throw new IllegalStateException("Must be called on the Main thread.");
40     }
41   }
42 }
43