Question

我正在开发一个android工作室项目，试图让图像每半小时更换一次，我跟着一个例子，但没有运气;它没有抛出任何错误，它只是不起作用，这就是我所拥有的我尝试了什么：

public class MainActivity extends AppCompatActivity {

long startTime = 0;
Handler feed = new Handler();
Runnable runTimer = new Runnable()
{
    @Override
    public void run() {
        Calendar now = Calendar.getInstance();
        TextView output = (TextView) findViewById(R.id.output);
        ImageView roto = (ImageView) findViewById(R.id.earthView);
        Globals g = (Globals) getApplication();
        int vision = 0;
        int visionb = 0;
        int hour = now.get(Calendar.HOUR);
        int minute = now.get(Calendar.MINUTE);
        String[] epos = g.getData56();

        if (minute >= 30) {
            visionb = 1;
        }
        if (minute < 30) {
            visionb = 0;
        }
        long millis = System.currentTimeMillis() - startTime;
        int seconds = (int) (millis / 1000);
        int minutes = seconds / 60;
        seconds = seconds % 60;
        output.setText(String.format("%d:%02d", minutes, seconds));
        vision = ((hour * 2) + visionb);
        int resID = getResources().getIdentifier(epos[vision], "drawable", getPackageName());
        if (roto != null) {
            roto.setImageResource(resID);
            feed.postDelayed(this, 500); // tried moving this around and changing the value from 0 - 3000
        }
        startTime = System.currentTimeMillis();
        feed.postDelayed(runTimer, 500); // tried moving this around and changing the value from 0 - 3000
    }
};

为了测试我的代码，我把它放在onUserInteraction方法中，它完全正常：

    @Override
    public void onUserInteraction() {
    super.onUserInteraction();
    final Globals g = (Globals) getApplication();
    Calendar now = Calendar.getInstance();
    ImageView roto = (ImageView) findViewById(R.id.earthView);
    int vision = 0;
    int visionb = 0;
    int hour = now.get(Calendar.HOUR);
    int minute = now.get(Calendar.MINUTE);
    String[] epos = g.getData56();

    if (minute >= 30) {
        visionb = 1;
    }
    if (minute < 30) {
        visionb = 0;
    }
    vision = ((hour * 2) + visionb);
    int resID = getResources().getIdentifier(epos[vision], "drawable", getPackageName());
    if (roto != null) {
        roto.setImageResource(resID);
    }
}

所以我认为我做错了什么，任何人都知道我做错了什么或错过了什么？

感谢帮助Landice这是工作结果，给我一个时钟和每半小时这一天改变了我的形象（共有48张图片），再次感谢您的帮助！

long startTime = 0;
{
final Handler feed = new Handler();
final Runnable runTimer = new Runnable() {
    @Override
    public void run() {

        Calendar now = Calendar.getInstance();
        TextView output = (TextView) findViewById(R.id.output);
        ImageView roto = (ImageView) findViewById(R.id.earthView);
        Globals g = (Globals) getApplication();
        int vision = 0;
        int visionb = 0;
        int second = now.get(Calendar.SECOND);
        int hour = now.get(Calendar.HOUR);
        int minute = now.get(Calendar.MINUTE);
        String[] epos = g.getData56();
        if (minute >= 30) {visionb = 1;}               
        if (minute < 30) {visionb = 0;}
        output.setText(String.format(hour + ":" + minute + ":" + second));
        feed.postDelayed(this, 0);
        if (minute == 30 || minute == 0) {vision = ((hour * 2) + visionb);
            int resID = getResources().getIdentifier(epos[vision], "drawable", getPackageName());
            if (roto != null) {
            roto.setImageResource(resID);
            }
        }
        startTime = System.currentTimeMillis();
    }
};
feed.postDelayed(runTimer,1000);
}

Answer 1

我想你忘了安排第一篇文章。这是使用Handler和Runnable来安排定期事件的示例。该行计划第一次运行。

handler.post(runTimer);

run（）内的这一行计划运行时的后续事件：

handler.postDelayed(this, 1000);

要注意1000意味着一秒钟。因此30分钟将是60 * 1000 * 30，在您的情况下为1800000。

示例：

public class MainActivity extends AppCompatActivity {

    TextView mTextView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mTextView = (TextView) findViewById(R.id.textview);

        final Handler handler = new Handler();
        Runnable runTimer = new Runnable()
        {
            @Override
            public void run() {
                mTextView.setText("Current Time: " + (new Date()).toString());
                handler.postDelayed(this, 1000);
            }
        };

        handler.post(runTimer);
    }
}

此外，您可能希望通过以下方式删除计划的延迟事件来停止循环：

handler.removeCallbacks(runTimer);

Answer 2

您可以尝试以下答案：How to change images in imageview every n number of seconds。

int[] imageArray = { R.drawable.image1, R.drawable.image2, R.drawable.image3, R.drawable.image4, R.drawable.image5 };

int position=0;

Timer mTimer = new Timer();

在特定时间更改图片

2 个答案: