Question

java中获取了当前系统地时间，怎样每秒获取更新一次呢？

这里是代码，请求大神帮忙补充完整，最好是后面加上注释，谢谢！
public class MainActivity extends ActionBarActivity
{
public String editText = "";
public Time clock = new Time();

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);//创建新的界面(super)属于父类
setContentView(R.layout.activity_main);//创建界面

if (savedInstanceState == null)
{
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}

}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item)
{//菜单以及菜单的响应
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings)
{
return true;
}
return super.onOptionsItemSelected(item);
}

/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment
{
private TextView tvResult=null;//新的TextV

private OnClickListener mListener = new OnClickListener()
{
@Override
public void onClick(View arg0)
{
if (arg0.getId() == R.id.btn1)
{
startActivity(new Intent(PlaceholderFragment.this.getActivity(), AddActivity.class));//启动那个类要告诉startActivity
}
else if (arg0.getId() == R.id.btn2)
{
startActivity(new Intent(PlaceholderFragment.this.getActivity(),SetupActivity.class));
}
}

};

// 构造函数 constructor
public PlaceholderFragment()
{

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
SimpleDateFormat formatter = new SimpleDateFormat ("yyyy年MM月dd日 HH:mm:ss ");
Date curDate = new Date(System.currentTimeMillis());//获取当前时间
String str = formatter.format(curDate);

View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
tvResult= (TextView)rootView.findViewById(R.id.tvResult);
tvResult.setText("Time");

tvResult.setText(formatter.format(curDate));

TextView btn1=(TextView)rootView.findViewById(R.id.btn1);
btn1.setText("添加闹钟");
TextView btn2=(TextView)rootView.findViewById(R.id.btn2);
btn2.setText("设置");

tvResult.setOnClickListener(mListener);
btn1.setOnClickListener(mListener);
btn2.setOnClickListener(mListener);

return rootView;
}
};

}

Answer 1

楼上说得不错,我补充一点,你先开启一个线程,然后在线程里面写一个死循环,让java代码不断的去获取系统时间,注意一定要把死循环放在你单独开启的那个线程里面,不然会出错哦. 可以用while(true){代码} 这种形式来写,循环代码里面主要包含两个内容,一个是获取系统当前时间,然后让线程睡眠一秒钟,就是调用Thread里面的sleep方法,这样就可以了

Answer 2

1、可以写个计数器多线程方式
2、多线程有继承Thread类 和 实现Runnable接口两种实现方式
3、一般会考虑用实现Runnable接口会更好一点，因为Runnable接口能够实现资源的共享

Answer 3

开启一个线程，每秒更新时间

Answer 4

Thread + Handler