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| public class Safe {
private Object me;
private Set set = new HashSet();
private Thread thread;
public void run() {
// Safe because "me" is not visible from any other thread
me = this;
// Safe because "set" is not visible from any other thread
set.add(this);
// Safe because MyThread won't start until construction is complete
// and the constructor doesn't publish the reference
thread = new MyThread(this);
}
public void run() {
thread.start();
}
private class MyThread(Object o) {
private Object theObject;
public MyThread(Object o) {
this.theObject = o;
}
...
}
}
public class Unsafe {
public static Unsafe anInstance;
public static Set set = new HashSet();
private Set mySet = new HashSet();
public void run() {
// Unsafe because anInstance is globally visible
anInstance = this;
// Unsafe because SomeOtherClass.anInstance is globally visible
SomeOtherClass.anInstance = this;
// Unsafe because SomeOtherClass might save the "this" reference
// where another thread could see it
SomeOtherClass.registerObject(this);
// Unsafe because set is globally visible
set.add(this);
// Unsafe because we are publishing a reference to mySet
mySet.add(this);
SomeOtherClass.someMethod(mySet);
// Unsafe because the "this" object will be visible from the new
// thread before the constructor completes
thread = new MyThread(this);
thread.start();
}
public void run() {
// Unsafe because "c" may be visible from other threads
c.add(this);
}
}
|
