退出程序的两种写法

废话不多说，直接上代码：

一、双击返回按钮退出登陆

   long lastTime = 0;

    /**
     * 2秒内连续点击back键，退出应用
     */
    @Override
    public void onBackPressed() {
        long curTime = System.currentTimeMillis();
        if ((curTime - lastTime) > 2000) {
               Toast.makeText(activity, "再按一次退出应用", Toast.LENGTH_SHORT).show();
            lastTime = curTime;
        } else {
           this.finish();
        }
    }

二、弹出一个对话框

private AlertDialog.Builder builder;
builder= getDialog(context);
builder.setMessage("退出登陆！");
builder.setPositiveButton("确定", onOkClickListener);
builder.setNegativeButton("取消", onCancleClickListener);
 @Override
    public void onBackPressed() {
     builder.show();
    }