如何在 Android 打开 DrawerLayout 时编辑导航菜单项标题

Question

在 Android 上，当在 DrawerLayout 中创建 NavigationView 时，可以通过 1) 获取 [= 的句柄来修改个人 MenuItems 的头衔17=] 主要 activity:

// Get a handle for the navigation view.
NavigationView navigationView = findViewById(R.id.navigationview);

// Get handles for the navigation menu items.
final Menu navigationMenu = navigationView.getMenu();
final MenuItem navigationFirstMenuItem = navigationMenu.getItem(0);
final MenuItem navigationSecondMenuItem = navigationMenu.getItem(1);
final MenuItem navigationThirdMenuItem = navigationMenu.getItem(2);

和 2) 使用 DrawerListener:

打开抽屉时修改菜单项的标题

// The drawer listener is used to update the navigation menu.
drawerLayout.addDrawerListener(new DrawerLayout.DrawerListener() {
    @Override
    public void onDrawerSlide(@NonNull View drawerView, float slideOffset) {
    }

    @Override
    public void onDrawerOpened(@NonNull View drawerView) {
    }

    @Override
    public void onDrawerClosed(@NonNull View drawerView) {
    }

    @Override
    public void onDrawerStateChanged(int newState) {
        if ((newState == DrawerLayout.STATE_SETTLING) || (newState == DrawerLayout.STATE_DRAGGING)) {  // A drawer is opening or closing.
            // Update the title of the menu items.
            navigationFirstMenuItem.setTitle(getString(R.string.newString));
            navigationSecondMenuItem.setEnabled(false);
            navigationThirdMenuItem.setTitle(getString(R.string.title) + " - " + counterInt);
            }
        }
    });

但是，一旦抽屉打开，尝试在不同线程上更改主菜单 activity 运行的一部分的菜单项之一的标题会导致以下错误，这会使应用程序崩溃：

W/System.err: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

例如，尝试从 WebViewClient.shouldInterceptRequest() 内部更新导航菜单项可能会产生此错误，如下所示：

// Get a handle for the WebView.
WebView webView = findViewById(R.id.webview);

// Set a WebViewClient.
webView.setWebViewClient(new WebViewClient() {
    @Override
    public WebResourceResponse shouldInterceptRequest(WebView view, String url){
        navigationFirstMenuItem.setTitle(getString(R.string.newString));
        navigationSecondMenuItem.setEnabled(false);
        navigationThirdMenuItem.setTitle(getString(R.string.title) + " - " + counterInt);
    }
}

问题是如何更新菜单项，例如，有一个在其中一个标题中递增的计数器，同时导航抽屉打开并且需要更新菜单项的事件是运行在不同的线程上。

Answer 1

正如@MikeM. 所建议的，问题的解决方案是使用 Activity.runOnUiThread() 从创建它的同一线程更新导航。具体来说，以下代码对我有用。

// Get a handle for the activity.  This is used to update the menu item titles while the navigation menu is open.
Activity activity = this;

// Get a handle for the WebView.
WebView webView = findViewById(R.id.webview);

// Set a WebViewClient.
webView.setWebViewClient(new WebViewClient() {
    @Override
    public WebResourceResponse shouldInterceptRequest(WebView view, String url){
        // Update the menu items' titles from the UI thread.
        activity.runOnUiThread(() -> {
            navigationFirstMenuItem.setTitle(getString(R.string.newString));
            navigationSecondMenuItem.setEnabled(false);
            navigationThirdMenuItem.setTitle(getString(R.string.title) + " - " + counterInt);
        });
    }
}

理解这个问题的关键是导航视图是由UI线程创建的。事后看来这似乎很明显，但错误消息并没有具体说明这一点，而且这种行为最初让我相信有一些专用的 DrawerLayout 线程只能通过 DrawerLayout 侦听器访问.

如何在 Android 打开 DrawerLayout 时编辑导航菜单项标题

How to edit a navigation menu item title while the DrawerLayout is open on Android

android

navigationview

android-navigationview