Java TimerTask中ArrayList的add()会导致所有元素都相同
我尝试向TimerTask中的ArrayList添加一些值。 但是在TimerTask的下一个实例中,所有先前添加的元素都设置为与当前元素相同 我做了一个小样本来说明我的问题:Java TimerTask中ArrayList的add()会导致所有元素都相同,java,arraylist,add,timertask,Java,Arraylist,Add,Timertask,我尝试向TimerTask中的ArrayList添加一些值。 但是在TimerTask的下一个实例中,所有先前添加的元素都设置为与当前元素相同 我做了一个小样本来说明我的问题: package connection; import java.util.ArrayList; import java.util.Timer; import java.util.TimerTask; import controls.PlotValuesContainer; public class Test {
package connection;
import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;
import controls.PlotValuesContainer;
public class Test
{
private ArrayList<PlotValuesContainer> m_logData;
private Timer m_timer;
public Test()
{
m_logData = new ArrayList<PlotValuesContainer>();
m_timer = new Timer();
m_timer.scheduleAtFixedRate(new UpdateThread(), 500, 500);
}
public static void main(String[] args)
{
new Test();
}
private class UpdateThread extends TimerTask
{
private PlotValuesContainer l_dataContainer = new PlotValuesContainer();
@Override
public boolean cancel()
{
return super.cancel();
}
@Override
public void run()
{
//store time stamp
l_dataContainer.setTimeStamp(java.time.LocalDateTime.now());
//store signal values
final short[] l_Array1to256 = new short[256];
for (int i = 0; i < l_Array1to256.length; i++)
{
l_Array1to256[i] = (short) (Math.random() * Short.MAX_VALUE);
}
l_dataContainer.setSignal(l_Array1to256);
if (m_logData.size() > 0)
{
System.out.println("A - oldest: " + m_logData.get(0).getTimeStamp().toString());
}
m_logData.add(l_dataContainer);
System.out.println("B - newest: " + m_logData.get((m_logData.size() - 1)).getTimeStamp().toString());
for (int i = 0; i < m_logData.size(); i++)
{
System.out.println("C - all: " + m_logData.get(i).getTimeStamp().toString());
}
}
}
}
我不是一个有经验的java程序员。。。
有人知道为什么会这样吗
非常感谢 将l_dataContainer的实例化移动到run方法中
private class UpdateThread extends TimerTask
{
private PlotValuesContainer l_dataContainer;
@Override
public boolean cancel()
{
return super.cancel();
}
@Override
public void run()
{
l_dataContainer = new PlotValuesContainer();
//store time stamp
l_dataContainer.setTimeStamp(java.time.LocalDateTime.now());
//store signal values
final short[] l_Array1to256 = new short[256];
for (int i = 0; i < l_Array1to256.length; i++)
{
l_Array1to256[i] = (short) (Math.random() * Short.MAX_VALUE);
}
l_dataContainer.setSignal(l_Array1to256);
if (m_logData.size() > 0)
{
System.out.println("A - oldest: " + m_logData.get(0).getTimeStamp().toString());
}
m_logData.add(l_dataContainer);
System.out.println("B - newest: " + m_logData.get((m_logData.size() - 1)).getTimeStamp().toString());
for (int i = 0; i < m_logData.size(); i++)
{
System.out.println("C - all: " + m_logData.get(i).getTimeStamp().toString());
}
}
}
private类UpdateThread扩展TimerTask
{
私有plotvalues容器l_数据容器;
@凌驾
公共布尔取消()
{
返回super.cancel();
}
@凌驾
公开募捐
{
l_dataContainer=新的绘图值container();
//存储时间戳
l_dataContainer.setTimeStamp(java.time.LocalDateTime.now());
//存储信号值
最终短路[]l_阵列1至256=新短路[256];
for(int i=0;i0)
{
println(“A-oldest:+m_logData.get(0.getTimeStamp().toString());
}
m_logData.add(l_数据容器);
System.out.println(“B-latest:+m_logData.get((m_logData.size()-1)).getTimeStamp().toString());
对于(int i=0;i
private class UpdateThread extends TimerTask
{
private PlotValuesContainer l_dataContainer;
@Override
public boolean cancel()
{
return super.cancel();
}
@Override
public void run()
{
l_dataContainer = new PlotValuesContainer();
//store time stamp
l_dataContainer.setTimeStamp(java.time.LocalDateTime.now());
//store signal values
final short[] l_Array1to256 = new short[256];
for (int i = 0; i < l_Array1to256.length; i++)
{
l_Array1to256[i] = (short) (Math.random() * Short.MAX_VALUE);
}
l_dataContainer.setSignal(l_Array1to256);
if (m_logData.size() > 0)
{
System.out.println("A - oldest: " + m_logData.get(0).getTimeStamp().toString());
}
m_logData.add(l_dataContainer);
System.out.println("B - newest: " + m_logData.get((m_logData.size() - 1)).getTimeStamp().toString());
for (int i = 0; i < m_logData.size(); i++)
{
System.out.println("C - all: " + m_logData.get(i).getTimeStamp().toString());
}
}
}