Android:从计时器线程访问 UI 元素 [英] Android: Accessing UI Element from timer thread

问题描述

public Button stb;
static int cnt=0;
public ArrayList<RadioButton> Butgrp1 = new ArrayList<RadioButton>();
Timer myt; 
TimerTask t;
stb.setOnClickListener(new OnClickListener() {

public void onClick(View v) {

myt.mschedule(new TimerTask() {

    @Override
    public void run() {

        // TODO Auto-generated method stub


        System.out.println("Entering run");
        Handler h=new Handler();

        h.post(new Runnable() {

            public void run() {

                // TODO Auto-generated method stub
                runOnUiThread(new Runnable() {

                    public void run() {
                        // TODO Auto-generated method stub
                        Butgrp1.get(cnt).setChecked(true);
                        cnt=cnt+1;
                        if(cnt>4)
                            cnt=0;
                        if(cnt>0)
                        //  Butgrp1.get(cnt-1).setChecked(false);
                        System.out.println(cnt);
                    }
                });


            }
        });

        //rg.getChildAt(cnt).setPressed(true);

    }
},1000,2000);

我需要访问 ui 上的一组单选按钮并将其设置为定期检查，但我不断收到不同的错误，我意识到我必须使用处理程序，但它仍然无法正常工作......任何人都可以请告诉我我哪里出错了......我是一个新手，正在尝试一些东西以更好地理解工作......请帮助......

I need to access a group of radio buttons on the ui and set it as checked at regular intervals, but i keep getting different errors, i realized i must use a handler, but its still not working...can anyone please tell me where i am going wrong....am a newbie and am trying out stuff to understand the working better...please help...

推荐答案

您必须在 UI 线程中创建 Handler，即在您的 的 onCreate活动.

You have to create the Handler in the UI Thread, i.e. in onCreate of your Activity.

因为您在后台线程的 run 方法中创建它，处理程序将在同一个后台线程中执行您的代码.

Because you create it in the run method of a background thread, the handler will execute your code in that very same background thread.

你也可以直接初始化你的Handler:

You could also initialize your Handler directly:

public class MyActivity extends Activity{

    private Handler handler = new Handler();

    //more code
}

然后不要使用runOnUIThread:

 handler.post(new Runnable() {
           public void run() {
                    // TODO Auto-generated method stub
                    Butgrp1.get(cnt).setChecked(true);
                    cnt=cnt+1;
                    if(cnt>4)
                        cnt=0;
                    if(cnt>0)
                    //  Butgrp1.get(cnt-1).setChecked(false);
                    System.out.println(cnt);
                }
            });

好的，试试这个清理过的代码.由于您没有发布完整的活动，因此无法立即使用:

Ok try this cleaned up code. Because you did not post your full Activity this won't work out of the box:

public class TestActivity extends Activity {

    private Button button;
    static int cnt=0;
    public ArrayList<RadioButton> buttonArray = new ArrayList<RadioButton>();
    private Timer timer = new Timer(); 

    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);

        button.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                timer.schedule(new MyTimerTask(), 1000,2000);
            }
        });
    }


    private void doButtonStuff(){
        buttonArray.get(cnt).setChecked(true);
        cnt=cnt+1;
        if(cnt>4){
            cnt=0;
        }
        if(cnt>0){
            //  Butgrp1.get(cnt-1).setChecked(false);
            System.out.println(cnt);
        }
    }

    private class MyTimerTask extends TimerTask{

        @Override
        public void run() {        
            runOnUiThread(new Runnable() {              
                @Override
                public void run() {
                    doButtonStuff();
                }
            });
        }       
    }
}

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