Android在退出应用程序时以及正在显示toast时取消Toast

Question

我在这里已经阅读过这类问题，但答案似乎没有起作用。

当用户点击按钮时，我会显示Toast。当用户不断点击按钮时，即使用户退出活动，烤面包也会一次又一次地显示。

吐司的长度很短。由于文本很长，因此无法更改Toast的长度。

这就是我现在所尝试的：

    Toast toast;
    toast=Toast.makeText(getApplicationContext(),"text",Toast.LENGTH_SHORT);
    if(toast.getView().isShown()==false){
         toast.show();
    }

这不起作用。

我试过了：

    if(toast.getView().isShown()==true){            
        toast.cancel();
    }

onStop()中的

。由于某种原因，取消方法永远不会有效。

如果我在显示应用程序之前放置.cancel()，那么将会有另一个空检查。但这样做之后也无效。我可以显示一个对话框而不是一个吐司，但这不是一个解决方案。

有没有办法检查是否正在显示吐司？

供参考

• Toast Message in Android

• How to avoid a Toast if there's one Toast already being shown

• How to prevent Multiple Toast Overlaps

• Cancelling an already open toast in Android

Answer 1

诀窍是跟踪显示的最后一个Toast，并取消那个。

我所做的是创建一个Toast包装器，其中包含对显示的最后一个Toast的静态引用。

当我需要显示一个新的时，我首先取消静态参考，然后再显示新参考（并将其保存在静态参考中）。

这是我制作的Boast包装器的完整代码 - 它模仿了Toast方法，足以让我使用它。默认情况下，Boast将取消前一个，因此您不会构建等待显示的Toasts队列。

这段代码可以在我的Github主旨中找到：

• mobiRic/Boast

如果您只是想知道如何在退出应用时取消通知，那么您会在那里找到很多帮助。如果您有改进或建议，请随意分叉并取得联系。这是一个非常古老的答案，但代码在一些应用程序的生产中已经稳定了一段时间。

BTW - 在大多数用例中，这应该是Toast 的直接替代品。

---

package mobi.glowworm.lib.ui.widget;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.Resources;
import android.support.annotation.Nullable;
import android.widget.Toast;

import java.lang.ref.WeakReference;

/**
 * {@link Toast} decorator allowing for easy cancellation of notifications. Use this class if you
 * want subsequent Toast notifications to overwrite current ones. </p>
 * <p/>
 * By default, a current {@link Boast} notification will be cancelled by a subsequent notification.
 * This default behaviour can be changed by calling certain methods like {@link #show(boolean)}.
 */
public class Boast {
    /**
     * Keeps track of certain Boast notifications that may need to be cancelled. This functionality
     * is only offered by some of the methods in this class.
     * <p>
     * Uses a {@link WeakReference} to avoid leaking the activity context used to show the original {@link Toast}.
     */
    @Nullable
    private volatile static WeakReference<Boast> weakBoast = null;

    @Nullable
    private static Boast getGlobalBoast() {
        if (weakBoast == null) {
            return null;
        }

        return weakBoast.get();
    }

    private static void setGlobalBoast(@Nullable Boast globalBoast) {
        Boast.weakBoast = new WeakReference<>(globalBoast);
    }


    // ////////////////////////////////////////////////////////////////////////////////////////////////////////

    /**
     * Internal reference to the {@link Toast} object that will be displayed.
     */
    private Toast internalToast;

    // ////////////////////////////////////////////////////////////////////////////////////////////////////////

    /**
     * Private constructor creates a new {@link Boast} from a given {@link Toast}.
     *
     * @throws NullPointerException if the parameter is <code>null</code>.
     */
    private Boast(Toast toast) {
        // null check
        if (toast == null) {
            throw new NullPointerException("Boast.Boast(Toast) requires a non-null parameter.");
        }

        internalToast = toast;
    }

    // ////////////////////////////////////////////////////////////////////////////////////////////////////////

    /**
     * Make a standard {@link Boast} that just contains a text view.
     *
     * @param context  The context to use. Usually your {@link android.app.Application} or
     *                 {@link android.app.Activity} object.
     * @param text     The text to show. Can be formatted text.
     * @param duration How long to display the message. Either {@link Toast#LENGTH_SHORT} or
     *                 {@link Toast#LENGTH_LONG}
     */
    @SuppressLint("ShowToast")
    public static Boast makeText(Context context, CharSequence text, int duration) {
        return new Boast(Toast.makeText(context, text, duration));
    }

    /**
     * Make a standard {@link Boast} that just contains a text view with the text from a resource.
     *
     * @param context  The context to use. Usually your {@link android.app.Application} or
     *                 {@link android.app.Activity} object.
     * @param resId    The resource id of the string resource to use. Can be formatted text.
     * @param duration How long to display the message. Either {@link Toast#LENGTH_SHORT} or
     *                 {@link Toast#LENGTH_LONG}
     * @throws Resources.NotFoundException if the resource can't be found.
     */
    @SuppressLint("ShowToast")
    public static Boast makeText(Context context, int resId, int duration)
            throws Resources.NotFoundException {
        return new Boast(Toast.makeText(context, resId, duration));
    }

    /**
     * Make a standard {@link Boast} that just contains a text view. Duration defaults to
     * {@link Toast#LENGTH_SHORT}.
     *
     * @param context The context to use. Usually your {@link android.app.Application} or
     *                {@link android.app.Activity} object.
     * @param text    The text to show. Can be formatted text.
     */
    @SuppressLint("ShowToast")
    public static Boast makeText(Context context, CharSequence text) {
        return new Boast(Toast.makeText(context, text, Toast.LENGTH_SHORT));
    }

    /**
     * Make a standard {@link Boast} that just contains a text view with the text from a resource.
     * Duration defaults to {@link Toast#LENGTH_SHORT}.
     *
     * @param context The context to use. Usually your {@link android.app.Application} or
     *                {@link android.app.Activity} object.
     * @param resId   The resource id of the string resource to use. Can be formatted text.
     * @throws Resources.NotFoundException if the resource can't be found.
     */
    @SuppressLint("ShowToast")
    public static Boast makeText(Context context, int resId) throws Resources.NotFoundException {
        return new Boast(Toast.makeText(context, resId, Toast.LENGTH_SHORT));
    }

    // ////////////////////////////////////////////////////////////////////////////////////////////////////////

    /**
     * Show a standard {@link Boast} that just contains a text view.
     *
     * @param context  The context to use. Usually your {@link android.app.Application} or
     *                 {@link android.app.Activity} object.
     * @param text     The text to show. Can be formatted text.
     * @param duration How long to display the message. Either {@link Toast#LENGTH_SHORT} or
     *                 {@link Toast#LENGTH_LONG}
     */
    public static void showText(Context context, CharSequence text, int duration) {
        Boast.makeText(context, text, duration).show();
    }

    /**
     * Show a standard {@link Boast} that just contains a text view with the text from a resource.
     *
     * @param context  The context to use. Usually your {@link android.app.Application} or
     *                 {@link android.app.Activity} object.
     * @param resId    The resource id of the string resource to use. Can be formatted text.
     * @param duration How long to display the message. Either {@link Toast#LENGTH_SHORT} or
     *                 {@link Toast#LENGTH_LONG}
     * @throws Resources.NotFoundException if the resource can't be found.
     */
    public static void showText(Context context, int resId, int duration)
            throws Resources.NotFoundException {
        Boast.makeText(context, resId, duration).show();
    }

    /**
     * Show a standard {@link Boast} that just contains a text view. Duration defaults to
     * {@link Toast#LENGTH_SHORT}.
     *
     * @param context The context to use. Usually your {@link android.app.Application} or
     *                {@link android.app.Activity} object.
     * @param text    The text to show. Can be formatted text.
     */
    public static void showText(Context context, CharSequence text) {
        Boast.makeText(context, text, Toast.LENGTH_SHORT).show();
    }

    /**
     * Show a standard {@link Boast} that just contains a text view with the text from a resource.
     * Duration defaults to {@link Toast#LENGTH_SHORT}.
     *
     * @param context The context to use. Usually your {@link android.app.Application} or
     *                {@link android.app.Activity} object.
     * @param resId   The resource id of the string resource to use. Can be formatted text.
     * @throws Resources.NotFoundException if the resource can't be found.
     */
    public static void showText(Context context, int resId) throws Resources.NotFoundException {
        Boast.makeText(context, resId, Toast.LENGTH_SHORT).show();
    }

    // ////////////////////////////////////////////////////////////////////////////////////////////////////////

    /**
     * Close the view if it's showing, or don't show it if it isn't showing yet. You do not normally
     * have to call this. Normally view will disappear on its own after the appropriate duration.
     */
    public void cancel() {
        internalToast.cancel();
    }

    /**
     * Show the view for the specified duration. By default, this method cancels any current
     * notification to immediately display the new one. For conventional {@link Toast#show()}
     * queueing behaviour, use method {@link #show(boolean)}.
     *
     * @see #show(boolean)
     */
    public void show() {
        show(true);
    }

    /**
     * Show the view for the specified duration. This method can be used to cancel the current
     * notification, or to queue up notifications.
     *
     * @param cancelCurrent <code>true</code> to cancel any current notification and replace it with this new
     *                      one
     * @see #show()
     */
    public void show(boolean cancelCurrent) {
        // cancel current
        if (cancelCurrent) {
            final Boast cachedGlobalBoast = getGlobalBoast();
            if ((cachedGlobalBoast != null)) {
                cachedGlobalBoast.cancel();
            }
        }

        // save an instance of this current notification
        setGlobalBoast(this);

        internalToast.show();
    }

}

Answer 2

而不是取消祝酒词。改变文字。例如

        Toast t;

        t = Toast.makeText(this, "hi", 3000);
        t.show();

当您需要不同的吐司时，请使用

        t.setText("bye");
        t.show();

如果你想解雇吐司，只需致电t.cancel()

Answer 3

您可以通过调用Toast对象上的cancel（）取消单个Toasts。 AFAIK，你无法取消所有出色的祝酒词。

Answer 4

尝试保留最后一片吐司的时间戳，并且在超时期限过去之前不要允许任何新的祝词。

类似的东西：

private static final long TOAST_TIMEOUT_MS = 2000; // tweak this constant

private static long lastToastTime = 0;

public void onButtonClicked() {
  long now = System.currentTimeMillis();
  if (lastToastTime + TOAST_TIMEOUT_MS < now) {
    Toast.makeText(...).show();
    lastToastTime = now;
  }
}

在用户退出应用程序后，我不会担心单个吐司会持续一秒钟 - 这是非常标准的行为。