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,它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,我首先取消静态引用,然后再显示新引用(并将其保存在静态中).

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：

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.

顺便说一句 – 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.

*

* 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.

*

* Uses a {@link WeakReference} to avoid leaking the activity context used to show the original {@link Toast}.

*/

@Nullable

private volatile static WeakReference 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 null.

*/

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 true 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();

}

}