我想在 Xamarin 中制作一个增量游戏，并且我制作了一些给我一个异常错误的计时器

Question

我是初学者，我想为 Android 制作一个带有橙色的点击器游戏，但是我收到一个空引用异常错误，我搜索了如何修复但仍然无法正常工作。 这是我的第一个问题。

这是我的 MainActivity.cs 代码

[Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
public class MainActivity : AppCompatActivity
{
    private AutoOrange AutoOrangeScript;

    public int oranges = 0;
    int OPC = 1;
    int upgradecost = 10;
    int blendercost = 50;
    public TextView orangestxt;
    TextView opctext;
    TextView opstext;
    ImageButton orangebtn;
    Button buyupgrade;
    Button buyblender;

    Timer Timerr;


    protected override void OnCreate(Bundle savedInstanceState)
    {




        base.OnCreate(savedInstanceState);
        Xamarin.Essentials.Platform.Init(this, savedInstanceState);
        SetContentView(Resource.Layout.activity_main);

        orangestxt = FindViewById<TextView>(OrangeClicker.Resource.Id.orangetext);
        opctext = FindViewById<TextView>(OrangeClicker.Resource.Id.opctxt);
        opstext = FindViewById<TextView>(OrangeClicker.Resource.Id.opstxt);
        orangebtn = FindViewById<ImageButton>(OrangeClicker.Resource.Id.orangebtn);
        buyupgrade = FindViewById<Button>(OrangeClicker.Resource.Id.buyupgrade);
        buyblender = FindViewById<Button>(OrangeClicker.Resource.Id.buyblender);

        orangebtn.Click += Orange_Click;
        buyupgrade.Click += BuyUpgrade_Click;
        buyblender.Click += BuyBlender_Click;

        AutoOrangeScript.AutoOrangeTimer.Interval = 1000;
        AutoOrangeScript.AutoOrangeTimer.Elapsed += new ElapsedEventHandler(AutoOrangeScript.AutoOrangeTimer_Tick);

        Timerr.Elapsed += new ElapsedEventHandler(Timer_Tick);
        Timerr.Interval = 100;
        Timerr.Enabled = true;

        buyupgrade.Text = "Upgrade Orange  -  " + upgradecost + " Oranges       +1 Per Click";
        buyblender.Text = "Buy Blender  -  " + blendercost + " Oranges          +1 Per Second";
        opctext.Text = "Oranges per click: " + OPC;
        opstext.Text = "Oranges per click: " + AutoOrangeScript.OPS;


    }




    void Orange_Click(object sender, System.EventArgs e)
    {

        oranges += OPC;
        orangestxt.Text = oranges + "  Oranges";
    }

    void Timer_Tick(object source, ElapsedEventArgs e)
    {        
        orangestxt.Text = oranges + "  Oranges";
        buyupgrade.Text = "Upgrade Orange  -  " + upgradecost + " Oranges       +1 Per Click";
        buyblender.Text = "Buy Blender  -  " + blendercost + " Oranges          +1 Per Second";
        opctext.Text = "Oranges per click: " + OPC;
        opstext.Text = "Oranges per click: " + AutoOrangeScript.OPS;
    }

    void BuyUpgrade_Click(object sender, System.EventArgs e)
    {
        if (oranges >= upgradecost)
        {
            oranges -= upgradecost;

            if (OPC > 10)
            {
                upgradecost += 20;
            } else {
                upgradecost += 10;
            }
            OPC += 1;

            opctext.Text = "Oranges per click: " + OPC;
            buyupgrade.Text = "Upgrade Orange  -  " + upgradecost + " Oranges       +1 Per Click";
        }          
    }

    void BuyBlender_Click(object sender, System.EventArgs e)
    {
        if (oranges >= blendercost)
        {
            oranges -= blendercost;
            AutoOrangeScript.OPS += 1;
            AutoOrangeScript.AutoOrangeTimer.Enabled = true;

            if (AutoOrangeScript.OPS > 10)
            {
                upgradecost += 20;
            } else
            {
                upgradecost += 10;
            }

            opstext.Text = "Oranges per second: " + AutoOrangeScript.OPS;
            buyblender.Text = "Upgrade Blender  -  " + blendercost + " Oranges          +1 Per Second";
        }
    }

}

这是我的第二个代码（AutoOrange.cs）

using System.Timers;

namespace OrangeClicker
{
    public class AutoOrange
    {
        private MainActivity MainActivityScript;

        public Timer AutoOrangeTimer;
        public int OPS;

        public void AutoOrangeTimer_Tick(object sender, System.EventArgs e)
        {

            MainActivityScript.oranges += OPS;
            MainActivityScript.orangestxt.Text = MainActivityScript.oranges + "Oranges";

        }

    }
}

在这里我得到了错误

AutoOrangeScript.AutoOrangeTimer.Interval = 1000; AutoOrangeScript.AutoOrangeTimer.Elapsed += new ElapsedEventHandler(AutoOrangeScript.AutoOrangeTimer_Tick);

 Timerr.Elapsed += new ElapsedEventHandler(Timer_Tick); Timerr.Interval = 100; Timerr.Enabled = true;

Answer 1

您订阅了值为 null 的Timerr ，因此它是一个 null 引用异常。 在此之前创建Timer 。