Android双击退出

重写返回键

private long tempTime = 0;

/**

 * 双击退出

 */

@Override

public void onBackPressed() {

    long firstClick = System.currentTimeMillis();

    if (firstClick - tempTime < 500) {

        ToastUtil.cancel();

        super.onBackPressed();

    } else {

        ToastUtil.show(this, "再按一次退出");

    }

    tempTime = firstClick;

}

Toast工具类

package com.bitmain.btccom.utils;

import android.content.Context;

import android.widget.Toast;

/**

 * Created by kongqw on 2015/11/21.

 */

public final class ToastUtil {

    private static Toast mToast;

    // 工具类私有化

    private ToastUtil() {

    }

    // 单例模式 显示Toast

    public static void show(Context context, String text) {

        if (null == mToast) {

            mToast = Toast.makeText(context, "", Toast.LENGTH_SHORT);

        }

        mToast.setText(text);

        mToast.show();

    }

    // 关闭Toast

    public static void cancel() {

        if (null != mToast)

            mToast.cancel();

    }

}