ToastUtils

public class ToastUtils {

    private static Toast toast;

    /**
     * 短時間顯示 Toast,位置居下
     *
     * @param msg 顯示字符串
     */
    public static void showShortToast(String msg) {
        if (getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(getAppContext(), msg, Toast.LENGTH_SHORT);
            } else {
                toast.setText(msg);
            }
        }
        toast.show();
    }

    /**
     * 短時間顯示 Toast,位置居中
     *
     * @param msg 顯示字符串
     */
    public static void showShortToastCenter(String msg) {
        if (getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(getAppContext(), msg, Toast.LENGTH_SHORT);
                toast.setGravity(Gravity.CENTER, 0, 0);
            } else {
                toast.setText(msg);
            }
        }
        toast.show();
    }

    /**
     * 短時間顯示Toast【居上】
     *
     * @param msg 顯示的內(nèi)容-字符串
     */
    public static void showShortToastTop(String msg) {
        if (MyAPP.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyAPP.getAppContext(), msg, Toast.LENGTH_SHORT);
                toast.setGravity(Gravity.TOP, 0, 0);
            } else {
                toast.setText(msg);
            }
            toast.show();
        }
    }

    /**
     * 長時間顯示Toast【居下】
     *
     * @param msg 顯示的內(nèi)容-字符串
     */
    public static void showLongToast(String msg) {
        if (MyAPP.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyAPP.getAppContext(), msg, Toast.LENGTH_LONG);
            } else {
                toast.setText(msg);
            }
            toast.show();
        }
    }

    /**
     * 長時間顯示Toast【居中】
     *
     * @param msg 顯示的內(nèi)容-字符串
     */
    public static void showLongToastCenter(String msg) {
        if (MyAPP.getAppContext() != null) {
            if (toast == null) {
                toast = Toast.makeText(MyAPP.getAppContext(), msg, Toast.LENGTH_LONG);
                toast.setGravity(Gravity.CENTER, 0, 0);
            } else {
                toast.setText(msg);
            }
            toast.show();
        }

MyAPP

public class MyAPP extends Application {

    private static Context AppContext;

    @Override
    public void onCreate() {
        super.onCreate();
        AppContext = getApplicationContext();
    }

    public static  Context getAppContext(){
        return AppContext;
    }
}