Android 8中的哪些更改使得可以从非ui线程更新UI

Question

对于下面的示例代码，它尝试从非ui线程更新UI，这在Android 4.x上崩溃但在Android 8上运行良好（这让我感到惊讶！）。

public class TestActivity extends AppCompatActivity {

private TextView mTextView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_test);

    mTextView = findViewById(R.id.test_text);
}

@Override
protected void onResume() {
    super.onResume();
    test2();
}

private void test2() {
    mTextView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            new Thread() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    Util.log("AAA thread name " + Thread.currentThread().getName());

                    mTextView.setText("AAA");
                }
            }.start();
        }
    });
}

}

想知道Android 8上的哪些更改使其有效。

编辑：在Android 4上崩溃的堆栈跟踪：

09-08 00:08:21.986 1811-1827/com.rainliu.androidexercise E/AndroidRuntime: FATAL EXCEPTION: Thread-107
                                                                           android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
                                                                               at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4607)
                                                                               at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:835)
                                                                               at android.view.View.requestLayout(View.java:15129)
                                                                               at android.view.View.requestLayout(View.java:15129)
                                                                               at android.view.View.requestLayout(View.java:15129)
                                                                               at android.view.View.requestLayout(View.java:15129)
                                                                               at android.view.View.requestLayout(View.java:15129)
                                                                               at android.view.View.requestLayout(View.java:15129)
                                                                               at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:292)
                                                                               at android.view.View.requestLayout(View.java:15129)
                                                                               at android.widget.TextView.checkForRelayout(TextView.java:6303)
                                                                               at android.widget.TextView.setText(TextView.java:3547)
                                                                               at android.widget.TextView.setText(TextView.java:3405)
                                                                               at android.widget.TextView.setText(TextView.java:3380)
                                                                               at com.rainliu.androidexercise.rxjava.RxJavaActivity$4$1.run(RxJavaActivity.java:320)

Answer 1

自API级别1以来，类Thread没有改变。

只是尝试过，而Thread.currentThread().getName()在使用main时使用.run()或Thread-2给我线程.start();虽然两者似乎都不是后台线程。

可以用Looper.myLooper() == Looper.getMainLooper()验证...

或者与Looper.getMainLooper().getThread() == Thread.currentThread()。

new Thread() {
    @Override
    public void run() {
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        if(Looper.myLooper() == Looper.getMainLooper()) {
            mTextView.setText(Thread.currentThread().getName());
        } else {
            Log.w(LOG_TAG, "not the main thread");
        }
    }
}.run();

只看到Processes and Threads，这解释了为什么这样做......

尽管它会阻止main线程一秒钟。

那么为什么它在Android 4.0上崩溃了，那里的线程名称是什么？

我刚刚发现了一个video，它解释了差异。