Android的活动生命周期 [英] Android Activity Life Cycle

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本文介绍了Android的活动生命周期的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

活动1开始活动2点击一个按钮。一旦为活动2静态内容设置，并显示给用户，我想揭开序幕的AsyncTask的。在AsyncTask的的执行的进度应显示给用户。 我的问题是，而不是进度发生活动2的重点是在这之后，活动1仍然可见，而AsyncTask的执行，然后切换到活动后2执行完成。我试过把我的AsyncTask的：

  • 的OnCreate
  • OnPostCreate
  • 的OnStart
  • OnResume

... 2活动，但活动2仍然只有一次执行任务的完成变得可见。什么点活动2的生命周期中，我需要把我的AsyncTask，以达到我想要什么？ code的情况下你需要它：

活动一开始的AsyncTask的前进之前验证用户的输入。在该任务的OnPostExecute，如果信息是有效的：

 意向意图=新的意图（_context的typeof（活性2））;
intent.PutExtra（呼叫，_call）;
intent.PutExtra（简称网站，_SITE）;
intent.PutExtra（服务类型，_serviceType）;
intent.PutExtra（优先级，_priority）;
_context.StartActivity（意向）;

Activity2.cs 

 公共类活性2：活动
{
    私人字符串电话{获得;组; }
    私人字符串网站{获得;组; }
    私人字符串优先{获得;组; }
    私人字符串服务类型{获取;组; }
    私人ViewAnimator动画{获得;组; }
    私人微调PrioritySpin {获得;组; }
    私人微调ProblemSpin {获得;组; }
    私人微调CauseSpin {获得;组; }
    私人微调RepairSpin {获得;组; }
    私人微调LaborHrsSpin {获得;组; }
    私人微调LaborDecSpin {获得;组; }
    私人微调TravelHrsSpin {获得;组; }
    私人微调TravelDecSpin {获得;组; }
    私人微调SerlModelSpin {获得;组; }

    保护覆盖无效的OnCreate（束捆）
    {
        base.OnCreate（包）;

        意向意图=意图;
        调用= intent.GetStringExtra（呼叫）;
        网站= intent.GetStringExtra（简称网站）;
        优先= intent.GetStringExtra（优先级）;
        的ServiceType = intent.GetStringExtra（服务类型）;

        标题=服务报告呼叫＃+电话+在现场+站点;

        的setContentView（Resource.Layout.Activity2）;

        动画=（ViewAnimator）FindViewById（Resource.Id.contentContainer）;

        按键基本=（按钮）FindViewById（Resource.Id.basicBtn）;
            basic.Click + = WizardClick;
        按钮设备=（按钮）FindViewById（Resource.Id.equipmentBtn）;
            equipment.Click + = WizardClick;
        按键部分=（按钮）FindViewById（Resource.Id.partsBtn）;
            parts.Click + = WizardClick;
        按钮评论=（按钮）FindViewById（Resource.Id.commentsBtn）;
            comments.Click + = WizardClick;
        按钮复习=（按钮）FindViewById（Resource.Id.reviewSubmit）;
            review.Click + = WizardClick;

        PrioritySpin =（微调）FindViewById（Resource.Id.prioritySpinner）;
        ProblemSpin =（微调）FindViewById（Resource.Id.problemSpinner）;
        CauseSpin =（微调）FindViewById（Resource.Id.causeSpinner）;
        RepairSpin =（微调）FindViewById（Resource.Id.repairSpinner）;
        LaborHrsSpin =（微调）FindViewById（Resource.Id.laborHrsSpinner）;
        LaborDecSpin =（微调）FindViewById（Resource.Id.laborDecSpinner）;
        TravelHrsSpin =（微调）FindViewById（Resource.Id.travelHrsSpinner）;
        TravelDecSpin =（微调）FindViewById（Resource.Id.travelDecSpinner）;

        ArrayAdapter＆LT;字符串＆GT; priorityAdapter =新的ArrayAdapter＆LT;字符串＆GT;（这一点，Android.Resource.Layout.SimpleSpinnerDropDownItem，优先级（））;
        ArrayAdapter＆LT;字符串＆GT; problemAdapter =新的ArrayAdapter＆LT;字符串＆GT;（这一点，Android.Resource.Layout.SimpleSpinnerDropDownItem，问题（））;
        ArrayAdapter＆LT;字符串＆GT; causeAdapter =新的ArrayAdapter＆LT;字符串＆GT;（这一点，Android.Resource.Layout.SimpleSpinnerDropDownItem，因为（））;
        ArrayAdapter＆LT;字符串＆GT; repairAdapter =新的ArrayAdapter＆LT;字符串＆GT;（这一点，Android.Resource.Layout.SimpleSpinnerDropDownItem，维修（））;
        ArrayAdapter＆LT;字符串＆GT; hoursAdapter =新的ArrayAdapter＆LT;字符串＆GT;（这一点，Android.Resource.Layout.SimpleSpinnerDropDownItem，时间（））;
        ArrayAdapter＆LT;字符串＆GT; decAdapter =新的ArrayAdapter＆LT;字符串＆GT;（这一点，Android.Resource.Layout.SimpleSpinnerDropDownItem，QuarterHours（））;

        PrioritySpin.Adapter = priorityAdapter;
        ProblemSpin.Adapter = problemAdapter;
        CauseSpin.Adapter = causeAdapter;
        RepairSpin.Adapter = repairAdapter;
        LaborHrsSpin.Adapter = hoursAdapter;
        LaborDecSpin.Adapter = decAdapter;
        TravelHrsSpin.Adapter = hoursAdapter;
        TravelDecSpin.Adapter = decAdapter;

        PrioritySpin.SetSelection（Convert.ToInt32（优先级））;

        如果（服务类型==PM）
        {
            ProblemSpin.SetSelection（Array.IndexOf（问题（），计划））;
            CauseSpin.SetSelection（Array.IndexOf（原因（），计划））;
        }

        Window.SetSoftInputMode（SoftInput.StateAlwaysHidden）;
    }

    保护覆盖无效OnResume（）
    {
        base.OnResume（）;

        SerlModelSpin =（微调）FindViewById（Resource.Id.equipSpinner）;

        IEquipment equipInterface =新EquipmentHelper（此，动画，5，0）;
        字符串[] equipList = equipInterface.GetEquipmentList（网站）;
        ArrayAdapter＆LT;字符串＆GT; equipAdapter =新的ArrayAdapter＆LT;字符串＆GT;（这一点，Android.Resource.Layout.SimpleSpinnerDropDownItem，equipList）;

        SerlModelSpin.Adapter = equipAdapter;
    }
}

解决方案

为什么很重要的活动，两个人在后台，而这AsyncTask的是在后台运行？用户会考虑要显示一个对话框......你为什么不把国旗在AsyncTask的，并等待设置标志并显示该对话框，直到 onResume（）方法执行结束。或者你可以尝试从活动之一，当活动调用静态start方法。或许，通过调用完成（），然后覆盖的onDestroy（）方法。它很难得到的时机。

Activity 1 starts Activity 2 with a button click. Once the static content for Activity 2 is set and displayed to the user, I want to kick off an AsyncTask. In the execution of the AsyncTask a ProgressBar should display to the user. My problem is that instead of the ProgressBar occurring after Activity 2 is focused, Activity 1 remains visible while the AsyncTask executes and then switches over to Activity 2 after execution is complete. I've tried placing my AsyncTask in:

  • OnCreate
  • OnPostCreate
  • OnStart
  • OnResume

...of Activity 2, but Activity 2 still only becomes visible once the task execution completes. What point in Activity 2's life cycle do I need to place my AsyncTask in order to achieve what I want? Code in case you need it:

Activity 1 starts an AsyncTask to validate the user's input before moving forward. In OnPostExecute of that task, if the information is valid:

Intent intent = new Intent(_context, typeof(Activity2));
intent.PutExtra("Call", _call);
intent.PutExtra("Site", _site);
intent.PutExtra("ServiceType", _serviceType);
intent.PutExtra("Priority", _priority);
_context.StartActivity(intent);

Activity2.cs

public class Activity2 : Activity
{
    private string Call { get; set; }
    private string Site { get; set; }
    private string Priority { get; set; }
    private string ServiceType { get; set; }
    private ViewAnimator Animator { get; set; }
    private Spinner PrioritySpin { get; set; }
    private Spinner ProblemSpin { get; set; }
    private Spinner CauseSpin { get; set; }
    private Spinner RepairSpin { get; set; }
    private Spinner LaborHrsSpin { get; set; }
    private Spinner LaborDecSpin { get; set; }
    private Spinner TravelHrsSpin { get; set; }
    private Spinner TravelDecSpin { get; set; }
    private Spinner SerlModelSpin { get; set; }

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        Intent intent = Intent;
        Call = intent.GetStringExtra("Call");
        Site = intent.GetStringExtra("Site");
        Priority = intent.GetStringExtra("Priority");
        ServiceType = intent.GetStringExtra("ServiceType");

        Title = "Service Report for Call #" + Call + " at Site " + Site;

        SetContentView(Resource.Layout.Activity2);

        Animator = (ViewAnimator) FindViewById(Resource.Id.contentContainer);

        Button basic = (Button) FindViewById(Resource.Id.basicBtn);
            basic.Click += WizardClick;
        Button equipment = (Button) FindViewById(Resource.Id.equipmentBtn);
            equipment.Click += WizardClick;
        Button parts = (Button) FindViewById(Resource.Id.partsBtn);
            parts.Click += WizardClick;
        Button comments = (Button) FindViewById(Resource.Id.commentsBtn);
            comments.Click += WizardClick;
        Button review = (Button) FindViewById(Resource.Id.reviewSubmit);
            review.Click += WizardClick;

        PrioritySpin = (Spinner) FindViewById(Resource.Id.prioritySpinner);
        ProblemSpin = (Spinner) FindViewById(Resource.Id.problemSpinner);
        CauseSpin = (Spinner) FindViewById(Resource.Id.causeSpinner);
        RepairSpin = (Spinner) FindViewById(Resource.Id.repairSpinner);
        LaborHrsSpin = (Spinner) FindViewById(Resource.Id.laborHrsSpinner);
        LaborDecSpin = (Spinner) FindViewById(Resource.Id.laborDecSpinner);
        TravelHrsSpin = (Spinner) FindViewById(Resource.Id.travelHrsSpinner);
        TravelDecSpin = (Spinner) FindViewById(Resource.Id.travelDecSpinner);

        ArrayAdapter<string> priorityAdapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleSpinnerDropDownItem, Priorities());
        ArrayAdapter<string> problemAdapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleSpinnerDropDownItem, Problems());
        ArrayAdapter<string> causeAdapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleSpinnerDropDownItem, Cause());
        ArrayAdapter<string> repairAdapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleSpinnerDropDownItem, Repair());
        ArrayAdapter<string> hoursAdapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleSpinnerDropDownItem, Hours());
        ArrayAdapter<string> decAdapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleSpinnerDropDownItem, QuarterHours());

        PrioritySpin.Adapter = priorityAdapter;
        ProblemSpin.Adapter = problemAdapter;
        CauseSpin.Adapter = causeAdapter;
        RepairSpin.Adapter = repairAdapter;
        LaborHrsSpin.Adapter = hoursAdapter;
        LaborDecSpin.Adapter = decAdapter;
        TravelHrsSpin.Adapter = hoursAdapter;
        TravelDecSpin.Adapter = decAdapter;

        PrioritySpin.SetSelection(Convert.ToInt32(Priority));

        if (ServiceType == "PM")
        {
            ProblemSpin.SetSelection(Array.IndexOf(Problems(), "Scheduled"));
            CauseSpin.SetSelection(Array.IndexOf(Cause(), "Scheduled"));
        }

        Window.SetSoftInputMode(SoftInput.StateAlwaysHidden);
    }

    protected override void OnResume()
    {
        base.OnResume();

        SerlModelSpin = (Spinner)FindViewById(Resource.Id.equipSpinner);

        IEquipment equipInterface = new EquipmentHelper(this, Animator, 5, 0);
        string[] equipList = equipInterface.GetEquipmentList(Site);
        ArrayAdapter<string> equipAdapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleSpinnerDropDownItem, equipList);

        SerlModelSpin.Adapter = equipAdapter;
    }
}

解决方案

Why is it important that activity two be in the background while this AsyncTask is running in the background? The user is going to be shown a dialog regardless... Why don't you put a flag in the AsyncTask, and wait to set the flag and display the dialog until the onResume() method has finished executing. Or you could try calling a static start method from activity one when activity. Perhaps by calling finish() and then overriding the onDestroy() method. Its hard to get that timing..

这篇关于Android的活动生命周期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！

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