Question

I create a simple Project to load all images in drawable

这是我的代码

public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    list = (ImageView)findViewById(R.id.tung);
    ct = getApplicationContext();
    try
    {
        IDs = getAllResourceIDs(R.drawable.class);
        n= IDs.length;
        dem=0;
        list.setOnClickListener(new View.OnClickListener()
         {
            public void onClick(View v)
            {
                ++dem;
                list.setImageResource(IDs[dem]);
                if(dem==n-1)
                    dem=0;
            }
        });

        Thread x = new Thread(
                new Runnable ()
                {
                    public void run()
                    {
                        while(true)
                        {
                            try
                            {
                                ++dem;
                                //Toast.makeText(ct, ""+dem, 20).show();
                                list.setImageResource(IDs[dem]);
                                if(dem==n-1)
                                    dem=0;
                            }
                            catch(Exception e)
                            {
                                //Toast.makeText(ct,e.toString(), 200).show();
                            }
                        }
                    }
                }
                );
        x.start();
    }
    catch(Exception e)
    {
        Toast.makeText(this,e.toString(), 200).show();
    }
}

这里是getAllResourceIDs函数来获取所有ID

private int[] getAllResourceIDs(Class<?> aClass) throws IllegalArgumentException{
    /* Get all Fields from the class passed. */
    Field[] IDFields = aClass.getFields();

    /* int-Array capable of storing all ids. */
    int[] IDs = new int[IDFields.length];

    try {
            /* Loop through all Fields and store id to array. */
            for(int i = 0; i < IDFields.length; i++){
                    /* All fields within the subclasses of R
                     * are Integers, so we need no type-check here. */

                    // pass 'null' because class is static
                    IDs[i] = IDFields[i].getInt(null);
            }
    } catch (Exception e) {
            /* Exception will only occur on bad class submitted. */
            throw new IllegalArgumentException();
    }
    return IDs;

文件main.xml只有一个id =“tung”的ImageView 我试图使用名为x的Thead加载所有图像通过使用代码 list.setImageResource（编号[DEM]）; 正如你在我的代码中看到的那样但事情没有发生你能帮我解释一下吗？非常感谢！

Answer 1

初学者catch (Exception e)几乎绝不是一个好主意，因为它隐藏了发生错误时可以获得的所有有意义的信息。

您的错误特别在后台线程的这一行：

list.setImageResource(IDs[dem]);

不允许后台线程操纵UI对象。相反，您需要使用AsyncTask（更简单）或Handler（高级）

Answer 2

JRaymond！非常感谢我创建一个Xthead类，像这样扩展Thread

class XThread extends Thread
{
    public int ids[];
    public ImageView icon;
    public int dem,n;
    XThread(int[] ids ,ImageView icon)
    {
        this.ids = ids;
        this.icon= icon;
        dem=0;
        n = ids.length;
    }

    public void run()
    {
        while(true)
        {
            try
            {
                Thread.sleep(500);
            handle.post(new Runnable()
            {
                public void run()
                {
                    ++dem;
                    icon.setImageResource(ids[dem]);
                    if(dem==n-1)
                        dem=0;
                }
            });
            }
            catch(Exception e)
            {

            }
        }
    }
}

和onCreate（）函数

XThread x = new XThread(IDs,list);
        x.start();

在Android中使用线程时获取Errs

2 个答案: