java - 在特定时间更改图像

标签 java android

我正在做一个 android studio 项目,试图让图像每半小时改变一次, 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 以及我的尝试:

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,我把它放在一个 onUserInteraction 方法中,它工作得很好:

    @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);
    }
}

所以我假设我做错了什么,有人知道我做错了什么或遗漏了什么吗?

感谢 Landice 的帮助 这是工作结果,给我一个时钟和每 1/2 小时 当天更改我的图像(共有 48 张图像),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);
}

最佳答案

我想你忘记安排第一篇文章了。 这是一个使用 Handler 和 Runnable 来安排周期性事件的例子。 此行安排第一次运行。

handler.post(runTimer);

并且 run() 中的这一行在它运行时安排了后续事件:

handler.postDelayed(this, 1000);

注意 1000 表示一秒。因此 30 分钟将为 60*1000*30,在您的情况下为 1800000。

例子:

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);

关于java - 在特定时间更改图像,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/36590149/

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