不要调用cancel()。尝试重置文本并调用show()。这将自动取消最后一个吐司

myToast.setText("wrong key")
myToast.show();

如果您继续使用相同的myToast，而不是每次都创建一个，我猜它们不会堆叠起来。

难道nandeesh的解决方案对你不起作用吗？他的解决方案比用两种不同的吐司要干净。
例如，（扩展他/她的答案）在onCreate之前，我们会声明吐司：

private Toast myToast;

在onCreate中我们必须使用makeToast初始化它（否则我们会得到一个错误）：

myToast = Toast.makeText(getApplicationContext(), null, Toast.LENGTH_SHORT);

每当我们想播放吐司时，我们只需调用：

myToast.setText("some text");
myToast.show();

这将取代之前的吐司。

以下是我从另一个类似问题中抄来的答案：

• Android cancel Toast when exiting the app and when toast is being shown

Boast类正好完成了您所需要的。
诀窍是跟踪显示的最后一个Toast，然后取消那个。
我所做的是创建一个Toast Package 器，它包含对最后显示的吐司的静态引用。
当我需要显示一个新对象时，我首先取消静态引用，然后再显示新对象（并将其保存在静态中）。
下面是我制作的Boast Package 器的完整代码--它模仿了吐司方法的很多部分，我可以使用它。默认情况下，Boast将取消前一个方法，因此您不会建立等待显示的Toast队列。
如果你只是想知道如何在退出应用程序时取消通知，你会在那里找到很多帮助。

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();
    }

}

创建一个java类***ShowToast.java***，如下所示

public class ShowToast {

        private static Toast toast;

        public static void show(Context mcontext, String text) {
            if (toast != null) 
               toast.cancel();
            toast = Toast.makeText(mcontext, text, Toast.LENGTH_SHORT);
            toast.show();
        }
    }

那就叫它

ShowToast.show(getApplicationContext(),"YOUR_TOAST_TEXT");

cancel()恐怕什么也做不了。
我建议使用Crouton https://github.com/keyboardsurfer/Crouton

这是我的解决方案工程完美的4.* 和2.3 Android版本

static Toast toast;
.....

if (toast != null)
    toast.cancel();

boolean condition = Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB;
if ((toast == null && condition) || !condition)
    toast = Toast.makeText(context, text, Toast.LENGTH_LONG);
if ((toast != null && condition))
    toast.setText(text);
toast.show();

创建吐司对象：

Toast toastobject=null;

现在使用下面的代码来显示吐司。

int index = clickCounter-1;

    if(toastobject!= null)
            {
                toastobject.cancel();
            }
            toastobject = Toast.makeText(this,"Toast Text" , Toast.LENGTH_SHORT);
            listItems.remove(index);
            toastobject.show();

创建一个新函数并调用它。

ImageButton ABtn = (ImageButton) findViewById(R.id.Btn);
ABtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v)
{       
SETToast("mytext");
}
});

    private Toast toast = null;

public void SETToast( String text)
{
  if(toast==null)
  {
     toast = Toast.makeText(getApplicationContext(), text, Toast.LENGTH_SHORT); 
     toast.show();
     final Handler handler = new Handler(); 
     handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            toast=null;
        }
     }, 2000);
  }
  else
  {
      toast.setText(text);
  }   
}

Kotlin方法：

class MyActivity: Activity {        
     private var toast: Toast? = null

     fun yourFunction() {
       toast?.cancel()

       toast = if(documentWasSaved) {
            makeText(this, "Document was saved"), Toast.LENGTH_LONG)
       } else {
            makeText(this, "Failed to save your document", Toast.LENGTH_LONG)
       }

       toast?.show()
    }
 }