Android自定義Toast，多次彈出時取消上次彈出，最后一次彈出為準

 
public abstract class Toast {
    public static final int LENGTH_SHORT = android.widget.Toast.LENGTH_SHORT;
    public static final int LENGTH_LONG = android.widget.Toast.LENGTH_LONG;


private static android.widget.Toast toast;
private static Handler handler = new Handler();

private static Runnable run = new Runnable() {
    public void run() {
        toast.cancel();
    }
};

private static void toast(Context ctx, CharSequence msg, int duration) {
    handler.removeCallbacks(run);
    // handler的duration不能直接對應Toast的常量時長，在此針對Toast的常量相應定義時長
    switch (duration) {
    case LENGTH_SHORT:// Toast.LENGTH_SHORT值為0，對應的持續時間大概為1s
        duration = 1000;
        break;
    case LENGTH_LONG:// Toast.LENGTH_LONG值為1，對應的持續時間大概為3s
        duration = 3000;
        break;
    default:
        break;
    }
    if (null != toast) {
        toast.setText(msg);
    } else {
        toast = android.widget.Toast.makeText(ctx, msg, duration);
    }
    handler.postDelayed(run, duration);
    toast.show();
}

/**
 * 彈出Toast
 * 
 * @param ctx
 *            彈出Toast的上下文
 * @param msg
 *            彈出Toast的內容
 * @param duration
 *            彈出Toast的持續時間
 */
public static void show(Context ctx, CharSequence msg, int duration)
        throws NullPointerException {
    if (null == ctx) {
        throw new NullPointerException("The ctx is null!");
    }
    if (0 > duration) {
        duration = LENGTH_SHORT;
    }
    toast(ctx, msg, duration);
}

/**
 * 彈出Toast
 * 
 * @param ctx
 *            彈出Toast的上下文
 * @param msg
 *            彈出Toast的內容的資源ID
 * @param duration
 *            彈出Toast的持續時間
 */
public static void show(Context ctx, int resId, int duration)
        throws NullPointerException {
    if (null == ctx) {
        throw new NullPointerException("The ctx is null!");
    }
    if (0 > duration) {
        duration = LENGTH_SHORT;
    }
    toast(ctx, ctx.getResources().getString(resId), duration);
}


}
</pre>