单击两次后退按钮退出活动 [英] Clicking the back button twice to exit an activity

问题描述

我最近在很多 Android 应用和游戏中都注意到了这种模式:当点击后退按钮退出"应用时，Toast 会出现类似于请点击再次返回退出".

我想知道，随着我越来越频繁地看到它，这是您可以在活动中以某种方式访问​​的内置功能吗?我查看了许多类的源代码，但似乎找不到任何相关内容.

当然，我可以考虑几种很容易实现相同功能的方法(最简单的方法可能是在 Activity 中保留一个布尔值来指示用户是否已经点击过一次...)但我想知道是否有东西已经在这里了.

编辑:正如@LAS_VEGAS 所提到的，我的意思并不是传统意义上的退出".(即终止)我的意思是回到应用程序启动活动启动之前打开的任何内容"，如果这是有道理的:)

解决方案

在 Java 活动中:

boolean doubleBackToExitPressedOnce = false;@覆盖公共无效 onBackPressed() {如果(doubleBackToExitPressedOnce){super.onBackPressed();返回;}this.doubleBackToExitPressedOnce = true;Toast.makeText(this, "请再次单击返回退出", Toast.LENGTH_SHORT).show();新处理程序(Looper.getMainLooper()).postDelayed(new Runnable() {@覆盖公共无效运行(){doubleBackToExitPressedOnce=false;}}, 2000);}

<块引用>

在 Kotlin 活动中:

private var doubleBackToExitPressedOnce = false覆盖乐趣 onBackPressed() {如果(doubleBackToExitPressedOnce){super.onBackPressed()返回}this.doubleBackToExitPressedOnce = trueToast.makeText(this, "请再次单击返回退出", Toast.LENGTH_SHORT).show()处理程序(Looper.getMainLooper()).postDelayed(Runnable { doubleBackToExitPressedOnce = false }, 2000)}

我认为这个处理程序有助于在 2 秒后重置变量.

I've noticed this pattern in a lot of Android apps and games recently: when clicking the back button to "exit" the application, a Toast comes up with a message similar to "Please click BACK again to exit".

I was wondering, as I'm seeing it more and more often, is that a built-in feature that you can somehow access in an activity? I've looked at the source code of many classes but I can't seem to find anything about that.

Of course, I can think about a few ways to achieve the same functionality quite easily (the easiest is probably to keep a boolean in the activity that indicates whether the user already clicked once...) but I was wondering if there's something already here.

EDIT: As @LAS_VEGAS mentioned, I didn't really mean "exit" in the traditional meaning. (i.e. terminated) I meant "going back to whatever was open before the application start activity was launched", if that makes sense :)

解决方案

In Java Activity:

boolean doubleBackToExitPressedOnce = false;

@Override
public void onBackPressed() {
    if (doubleBackToExitPressedOnce) {
        super.onBackPressed();
        return;
    }
        
    this.doubleBackToExitPressedOnce = true;
    Toast.makeText(this, "Please click BACK again to exit", Toast.LENGTH_SHORT).show();
        
    new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
        
        @Override
        public void run() {
            doubleBackToExitPressedOnce=false;                       
        }
    }, 2000);
} 

In Kotlin Activity:

private var doubleBackToExitPressedOnce = false
override fun onBackPressed() {
        if (doubleBackToExitPressedOnce) {
            super.onBackPressed()
            return
        }

        this.doubleBackToExitPressedOnce = true
        Toast.makeText(this, "Please click BACK again to exit", Toast.LENGTH_SHORT).show()

        Handler(Looper.getMainLooper()).postDelayed(Runnable { doubleBackToExitPressedOnce = false }, 2000)
    }

I Think this handler helps to reset the variable after 2 second.

这篇关于单击两次后退按钮退出活动的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！