Threadlocal implementing thread-scoped shared variables

I. How to understand the shared data within a thread range

1, static int num=0;

2. Thread 1 accesses the NUM variable and is set to num=2; thread 2 accesses the NUM variable and is set to num=3;

3, when the object A, B, C in thread 1 accesses the NUM variable in thread 1, it is not the value set by itself, how can I get thread 1 to access the data set by it itself?

 Public classSharedata {Private Static DoubleNum=0;  Public Static voidMain (string[] args) {//There are 2 threads at a time         for(inti=0;i<2;i++){            NewThread (NewRunnable () {@Override Public voidrun () {//TODO auto-generated Method Stub//each thread changes num's datanum=NewRandom (). nextdouble (); System.out.println (Thread.CurrentThread (). GetName ()+ "has a put num:" +num); //call the objects of A, B, respectively                    NewA (). get (); NewB (). get ();        }}). Start (); }    }    //A object outputs the data for NUM in the current thread    Static classa{ Public voidget () {System.out.println (Thread.CurrentThread (). GetName ()+ "has a num---A:" +num); }    }    //the B object outputs the data for NUM in the current thread    Static classb{ Public voidget () {System.out.println (Thread.CurrentThread (). GetName ()+ "has a num---B:" +num); }    }}

Results Analysis:

Second, using the map collection to implement thread-wide shared data

1, private static map<thread,double> map=new hashmap<thread,double> ();

Use the Map collection to maintain the individual variables in each thread.

 Public classThreadscopesharenum {//global shared variable num    Private Static DoubleNum=0; //put the thread as a keyword, set the value of NUM as the value put into the map collection    Private StaticMap<thread,double> map=NewHashmap<thread,double>();  Public Static voidMain (string[] args) {//maintenance of two threads         for(inti=0;i<2;i++){            NewThread (NewRunnable () {@Override Public voidrun () {//set the value of NUM and save it to CurrentThread                    Doublenum=NewRandom (). nextdouble ();                    Map.put (Thread.CurrentThread (), num); System.out.println (Thread.CurrentThread (). GetName ()+ "has a put num:" +num); //A, b objects Get values by CurrentThread                    NewA (). get (); NewB (). get ();        }}). Start (); }    }    //A object outputs the data for NUM in the current thread        Static classa{ Public voidget () {System.out.println (Thread.CurrentThread (). GetName ()+ "has a num---A:" +Map.get (Thread.CurrentThread ())); }        }        //the B object outputs the data for NUM in the current thread        Static classb{ Public voidget () {System.out.println (Thread.CurrentThread (). GetName ()+ "has a num---B:" +Map.get (Thread.CurrentThread ())); }        }}

Results Analysis:

Threadlocal shared variables that implement thread scope (1 x）

1. new Threadlocal<t> (); A variable of type T is guaranteed to be shared correctly within the thread range.
2. Public void Set (T value);//content maintains a map collection, and key defaults to the current thread.
3. Public T get ();//Remove the value of the current thread, variable.

ImportJava.util.HashMap;ImportJava.util.Map;ImportJava.util.Random; Public classThreadscopesharenum {//global shared variable num    Private Static DoubleNum=0; //put the thread as a keyword, set the value of NUM as the value put into the map collection    Private StaticThreadlocal<double> map=NewThreadlocal<double>();  Public Static voidMain (string[] args) {//maintenance of two threads         for(inti=0;i<2;i++){            NewThread (NewRunnable () {@Override Public voidrun () {//set the value of NUM and save it to CurrentThread                    Doublenum=NewRandom (). nextdouble ();                    Map.set (num); System.out.println (Thread.CurrentThread (). GetName ()+ "has a put num:" +num); //A, b objects Get values by CurrentThread                    NewA (). get (); NewB (). get ();        }}). Start (); }    }    //A object outputs the data for NUM in the current thread        Static classa{ Public voidget () {System.out.println (Thread.CurrentThread (). GetName ()+ "has a num---A:" +map.get ()); }        }        //the B object outputs the data for NUM in the current thread        Static classb{ Public voidget () {System.out.println (Thread.CurrentThread (). GetName ()+ "has a num---B:" +map.get ()); }        }}

Iv. How to implement thread-wide through threadlocalmultipleShared variables

Threadlocal implementing thread-scoped shared variables