android - 如何从另一个 Intent 中取消我在先前 Activity 中定义的 toast 消息？

Question

在我将 Intent 传递给另一个类 UPCHandler 之后，我无法关闭我在 Activity BarcodeActivity 中创建的 toast 消息。由于我无法通过 Intent 传递 toast，因此我无法找到一种方法来从 UPCHandler Intent 中操作 toast 消息。

条码 Activity :

public void didScanBarcode(String barcode, String symbology) 
{
    // Remove non-relevant characters that might be displayed as rectangles
    // on some devices. Be aware that you normally do not need to do this.
    // Only special GS1 code formats contain such characters.
    String cleanedBarcode = "";

    for (int i = 0 ; i < barcode.length(); i++) 
    {
        if (barcode.charAt(i) > 30) 
        {
            cleanedBarcode += barcode.charAt(i);
        }
    }

    try
    {
        //stops scanner
        mBarcodePicker.stopScanning();
        Log.e("CleanedUPC", cleanedBarcode);

        /* Toast Setup */
        LayoutInflater inflater = getLayoutInflater();
        View layout = inflater.inflate(R.layout.toast_layout,
                                       (ViewGroup) findViewById(R.id.toast_layout_root));

        TextView text = (TextView) layout.findViewById(R.id.text);
        text.setText("Fetching your results...");

        Toast toast = BarcodeActivity.toast;
        toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
        toast.setDuration(Toast.LENGTH_LONG);
        toast.setView(layout); 
        toast.show();

            @Override
            public String dataRetreived() 
            {/*
                Intent i = new Intent(getApplicationContext(), UPCHandler.class);

                Bundle bundle = new Bundle();
                bundle.put("value", inputTransacVal.getText());

                i.putExtras(bundle);

                startActivity(i);*/
                ItemsDto idt = hand.getFirstUpc();

                if (idt == null) 
                {
                    Log.e("BarcodeActivity:didScanBarcode", "UPC is NULL");
                    toast.cancel();
                } 
                else 
                {
                    Intent intn_display = new Intent("com.ahold.scan.DISPLAYSCREEN");
                    Intent intn_warning = new Intent("com.ahold.scan.WARNINGSCREEN");

                    ImageLoader imgLoad = new ImageLoader(idt.getImageUrl(), context, idt)


                    */

                }
                return null;

            }
        });

    }
    catch(Exception e)
    {
        //throws an error message to logcat if it catches one
        Log.e("IntentStartError", e.toString());
    }
}

Answer 1

您可以尝试做两件事:

1. 在切换 Activity 之前关闭 Toast，在您的 Intent 中传递需要重新显示 Toast 的指示，并在新 Activity 中显示它。
2. 传递 toast 。将它放在某处的静态变量中，如果它不为空，则在您的新 Activity 中将其取消。请记住，它可能为空，因为 Android 可以终止您的进程并在 Activity 之间再次启动它。