我是Java Threads的新手。我想要做的是从ThreadB对象获得对当前运行的线程(ThreadA)的实例的访问,并调用其名为setSomething的方法。 1)我认为我比实际做得更努力 2)我有一个空指针异常,因此访问该方法时我必须做错事
到目前为止,我已经完成了尽职调查,并在StackOverflow上查看了类似的问题。
我有一个当前的Thread在后台运行:
// assume this thread is called by some other application
public class ThreadA implements Runnable{
private Thread aThread;
public ThreadA(){
aThread = new Thread(this);
aThread.setName("AThread");
aThread.start();
}
@Override
public void run(){
while(true){
// doing something
}
}
public void setSomething(String status){
// process something
}
}
// assume this thread is started by another application
public class ThreadB implements Runnable{
@Override
public void run(){
passAValue("New");
}
public void passAValue(String status){
// What I am trying to do is to get the instance of ThreadA and call
// its method setSomething but I am probably making it harder on myself
// not fully understanding threads
Method[] methods = null;
// get all current running threads and find the thread i want
Set<Thread> threadSet = Thread.getAllStackTraces().keySet();
for(Thread t : threadSet){
if(t.getName().equals("AThread")){
methods = t.getClass().getMethods();
}
}
//**How do I access ThreadA's method, setSomething**
}
}
提前谢谢
阿伦
答案 0 :(得分:4)
好的,你需要做的就是将threadA引用传递给threadB!只是这个。让我说当你从线程b调用一个方法时,所以它由线程b运行,而不是该类已被托管。
class ThreadA implements Runnable{
public void run(){
//do something
}
public void setSomething(){}
}
class ThreadB implements Runnable{
private ThreadA aref;
public ThreadB(ThreadA ref){aref=ref;}
public void run(){
aref.setSomething();//calling the setSomething() with this thread!! no thread a
}
}
class Foo{
public static void main(String...arg){
ThreadA a=new ThreadA();
new Thread(a).start();
ThreadB b=new ThreadB(b);
new Thread(b).start();
}
}
和here一个简单的线程教程
答案 1 :(得分:1)
在实例化ThreadB对象时或之后,为其提供对ThreadA对象实例的引用。类似的东西:
ThreadA a = new ThreadA();
ThreadB b = new ThreadB(a);
然后,在ThreadB代码中,您可以通过使用毫无疑问存储在ThreadB中的实例变量中的引用来调用ThreadA的方法。