import java.io.*;
class sleeper extends Thread
{
private int time;
sleeper(String name,int runtime)
{
super(name);
time=runtime;
start();
}
public void run()
{
try
{
sleep(time);
}
catch(InterruptedException e)
{
System.out.println(getName()+"has interrupted");
}
System.out.println(getName()+" has wakend");
}
}
class joiner extends Thread
{
private sleeper sleeper;
private int time;
joiner(String name,int runtime)
{
super(name);
time=runtime;
start();
}
public void run()
{
try
{
sleep(time);
sleeper.join();
}
catch(InterruptedException e)
{
System.out.println(getName()+" was interrupted");
}
System.out.println(getName()+" join compelted");
}
}
public class trdx
{
public static void main(String args[])
{
joiner joiner1=new joiner("killtry",403),
joiner2=new joiner("howarld",201);
sleeper sleeper1=new sleeper("kelvin",403); sleeper2=new sleeper("legend",201);
}
}
==========================================================================
编译结果:can not find symbol请问问题出在那里啊?谢谢~!
class sleeper extends Thread
{
private int time;
sleeper(String name,int runtime)
{
super(name);
time=runtime;
start();
}
public void run()
{
try
{
sleep(time);
}
catch(InterruptedException e)
{
System.out.println(getName()+"has interrupted");
}
System.out.println(getName()+" has wakend");
}
}
class joiner extends Thread
{
private sleeper sleeper;
private int time;
joiner(String name,int runtime)
{
super(name);
time=runtime;
start();
}
public void run()
{
try
{
sleep(time);
sleeper.join();
}
catch(InterruptedException e)
{
System.out.println(getName()+" was interrupted");
}
System.out.println(getName()+" join compelted");
}
}
public class trdx
{
public static void main(String args[])
{
joiner joiner1=new joiner("killtry",403),
joiner2=new joiner("howarld",201);
sleeper sleeper1=new sleeper("kelvin",403); sleeper2=new sleeper("legend",201);
}
}
==========================================================================
编译结果:can not find symbol请问问题出在那里啊?谢谢~!
sleeper sleeper2=new sleeper("legend",201);
Exception in thread "howarld" java.lang.NullPointerException
at joiner.run(trdx.java:39)legend has wakendException in thread "killtry" java.lang.NullPointerException
at joiner.run(trdx.java:39)kelvin has wakend
================================================================================