Changing an arrays elements with thread

-2

I need the change the elements of an array by using a thread. It should change (add or sub an integer number) an element randomly, sleep for 2 sec and change another one randomly.

So i created my array and my thread, but I don't know how to change it.

public static void main(String args) {



    int  myarray= new int[5]; 

    Thread x= new Thread();

    x.start(); 



    try 

        {

            x.sleep(2000);

        }

        catch(InterruptedException ex)

        {

            Thread.currentThread().interrupt();

        }



}



}

public class myThread implements Runnable {

   public myThread(){ //an empty constructor, to pass parameters



   }

    public void run(){



    }

    public void update(){ //i tohught i could use that for changing elements



    }

edited Jan 1 at 22:16

Paul Rooney

12.7k72845

asked Jan 1 at 21:34

sadclown

1

Unrelated: x.sleep(2000) is bad code. Method sleep is static, so should be called by qualifying with the class name, not with an instance value, so it should be Thread.sleep(2000)

– Andreas
Jan 1 at 21:43

You need to pass the array into the thread as a parameter to the constructor. Also, you need to actually use the myThread class. Note that Java naming convention is for class names to start with uppercase letter, so it should be called MyThread.

– Andreas
Jan 1 at 21:45

add a comment |

-2

I need the change the elements of an array by using a thread. It should change (add or sub an integer number) an element randomly, sleep for 2 sec and change another one randomly.

So i created my array and my thread, but I don't know how to change it.

public static void main(String args) {



    int  myarray= new int[5]; 

    Thread x= new Thread();

    x.start(); 



    try 

        {

            x.sleep(2000);

        }

        catch(InterruptedException ex)

        {

            Thread.currentThread().interrupt();

        }



}



}

public class myThread implements Runnable {

   public myThread(){ //an empty constructor, to pass parameters



   }

    public void run(){



    }

    public void update(){ //i tohught i could use that for changing elements



    }

edited Jan 1 at 22:16

Paul Rooney

12.7k72845

asked Jan 1 at 21:34

sadclown

1

Unrelated: x.sleep(2000) is bad code. Method sleep is static, so should be called by qualifying with the class name, not with an instance value, so it should be Thread.sleep(2000)

– Andreas
Jan 1 at 21:43

You need to pass the array into the thread as a parameter to the constructor. Also, you need to actually use the myThread class. Note that Java naming convention is for class names to start with uppercase letter, so it should be called MyThread.

– Andreas
Jan 1 at 21:45

add a comment |

-2

I need the change the elements of an array by using a thread. It should change (add or sub an integer number) an element randomly, sleep for 2 sec and change another one randomly.

So i created my array and my thread, but I don't know how to change it.

public static void main(String args) {



    int  myarray= new int[5]; 

    Thread x= new Thread();

    x.start(); 



    try 

        {

            x.sleep(2000);

        }

        catch(InterruptedException ex)

        {

            Thread.currentThread().interrupt();

        }



}



}

public class myThread implements Runnable {

   public myThread(){ //an empty constructor, to pass parameters



   }

    public void run(){



    }

    public void update(){ //i tohught i could use that for changing elements



    }

edited Jan 1 at 22:16

Paul Rooney

12.7k72845

asked Jan 1 at 21:34

sadclown

I need the change the elements of an array by using a thread. It should change (add or sub an integer number) an element randomly, sleep for 2 sec and change another one randomly.

So i created my array and my thread, but I don't know how to change it.

public static void main(String args) {



    int  myarray= new int[5]; 

    Thread x= new Thread();

    x.start(); 



    try 

        {

            x.sleep(2000);

        }

        catch(InterruptedException ex)

        {

            Thread.currentThread().interrupt();

        }



}



}

public class myThread implements Runnable {

   public myThread(){ //an empty constructor, to pass parameters



   }

    public void run(){



    }

    public void update(){ //i tohught i could use that for changing elements



    }

java arrays multithreading

edited Jan 1 at 22:16

Paul Rooney

12.7k72845

asked Jan 1 at 21:34

sadclown

edited Jan 1 at 22:16

Paul Rooney

12.7k72845

asked Jan 1 at 21:34

sadclown

edited Jan 1 at 22:16

Paul Rooney

12.7k72845

edited Jan 1 at 22:16

Paul Rooney

12.7k72845

edited Jan 1 at 22:16

Paul Rooney

12.7k72845

asked Jan 1 at 21:34

sadclown

asked Jan 1 at 21:34

sadclown

asked Jan 1 at 21:34

sadclown

1

Unrelated: x.sleep(2000) is bad code. Method sleep is static, so should be called by qualifying with the class name, not with an instance value, so it should be Thread.sleep(2000)

– Andreas
Jan 1 at 21:43

You need to pass the array into the thread as a parameter to the constructor. Also, you need to actually use the myThread class. Note that Java naming convention is for class names to start with uppercase letter, so it should be called MyThread.

– Andreas
Jan 1 at 21:45

add a comment |

1

Unrelated: x.sleep(2000) is bad code. Method sleep is static, so should be called by qualifying with the class name, not with an instance value, so it should be Thread.sleep(2000)

– Andreas
Jan 1 at 21:43

You need to pass the array into the thread as a parameter to the constructor. Also, you need to actually use the myThread class. Note that Java naming convention is for class names to start with uppercase letter, so it should be called MyThread.

– Andreas
Jan 1 at 21:45

Unrelated: x.sleep(2000) is bad code. Method sleep is static, so should be called by qualifying with the class name, not with an instance value, so it should be Thread.sleep(2000)

– Andreas
Jan 1 at 21:43

You need to pass the array into the thread as a parameter to the constructor. Also, you need to actually use the myThread class. Note that Java naming convention is for class names to start with uppercase letter, so it should be called MyThread.

– Andreas
Jan 1 at 21:45

add a comment |

1 Answer
1

active

oldest

votes

First, you have to create an class declaration, that accepts required arr and implements run() method with logic.

public static class MyThread implements Runnable {



    private final int arr;

    private final Random random = new Random();



    private MyThread(int arr) {

        this.arr = arr;

    }



    @Override

    public void run() {

        try {

            while (true) {

                // wait for 2 seconds

                Thread.sleep(TimeUnit.SECONDS.toMillis(2));

                // randomly choose array element

                int i = random.nextInt(arr.length);

                // randomly choose increment or decrement an elements

                boolean add = random.nextBoolean();



                // lock WHOLE array for modification

                synchronized (arr) {

                    arr[i] = add ? arr[i] + 1 : arr[i] - 1;

                }

            }

        } catch(InterruptedException e) {

        }

    }

}

Second, you have to create an array and required number of threads for modifications.

// create an array

int arr = new int[5];



// create threads and start

for (int i = 0; i < 20; i++)

    new Thread(new MyThread(arr)).start();

That's all basically. Sure, it is possible to not lock whole array to modify only one elements, but this is another story.

edited Jan 1 at 23:37

answered Jan 1 at 21:54

oleg.cherednik

7,16021119

The final println(...) call in your main routine can be executed while worker threads still are running. Not that anybody would be able to tell by examining the program's output, but still... Are you sure that's what you wanted to show?

– Solomon Slow
Jan 1 at 23:36

I dont understand why output is [0, 0, 0, 0, 0]

– sadclown
Jan 1 at 23:50

Wait until all threads will be stopped

– oleg.cherednik
Jan 1 at 23:51

add a comment |

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1 Answer
1

active

oldest

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1 Answer
1

active

oldest

votes

First, you have to create an class declaration, that accepts required arr and implements run() method with logic.

public static class MyThread implements Runnable {



    private final int arr;

    private final Random random = new Random();



    private MyThread(int arr) {

        this.arr = arr;

    }



    @Override

    public void run() {

        try {

            while (true) {

                // wait for 2 seconds

                Thread.sleep(TimeUnit.SECONDS.toMillis(2));

                // randomly choose array element

                int i = random.nextInt(arr.length);

                // randomly choose increment or decrement an elements

                boolean add = random.nextBoolean();



                // lock WHOLE array for modification

                synchronized (arr) {

                    arr[i] = add ? arr[i] + 1 : arr[i] - 1;

                }

            }

        } catch(InterruptedException e) {

        }

    }

}

Second, you have to create an array and required number of threads for modifications.

// create an array

int arr = new int[5];



// create threads and start

for (int i = 0; i < 20; i++)

    new Thread(new MyThread(arr)).start();

That's all basically. Sure, it is possible to not lock whole array to modify only one elements, but this is another story.

edited Jan 1 at 23:37

answered Jan 1 at 21:54

oleg.cherednik

7,16021119

The final println(...) call in your main routine can be executed while worker threads still are running. Not that anybody would be able to tell by examining the program's output, but still... Are you sure that's what you wanted to show?

– Solomon Slow
Jan 1 at 23:36

I dont understand why output is [0, 0, 0, 0, 0]

– sadclown
Jan 1 at 23:50

Wait until all threads will be stopped

– oleg.cherednik
Jan 1 at 23:51

add a comment |

First, you have to create an class declaration, that accepts required arr and implements run() method with logic.

public static class MyThread implements Runnable {



    private final int arr;

    private final Random random = new Random();



    private MyThread(int arr) {

        this.arr = arr;

    }



    @Override

    public void run() {

        try {

            while (true) {

                // wait for 2 seconds

                Thread.sleep(TimeUnit.SECONDS.toMillis(2));

                // randomly choose array element

                int i = random.nextInt(arr.length);

                // randomly choose increment or decrement an elements

                boolean add = random.nextBoolean();



                // lock WHOLE array for modification

                synchronized (arr) {

                    arr[i] = add ? arr[i] + 1 : arr[i] - 1;

                }

            }

        } catch(InterruptedException e) {

        }

    }

}

Second, you have to create an array and required number of threads for modifications.

// create an array

int arr = new int[5];



// create threads and start

for (int i = 0; i < 20; i++)

    new Thread(new MyThread(arr)).start();

That's all basically. Sure, it is possible to not lock whole array to modify only one elements, but this is another story.

edited Jan 1 at 23:37

answered Jan 1 at 21:54

oleg.cherednik

7,16021119

The final println(...) call in your main routine can be executed while worker threads still are running. Not that anybody would be able to tell by examining the program's output, but still... Are you sure that's what you wanted to show?

– Solomon Slow
Jan 1 at 23:36

I dont understand why output is [0, 0, 0, 0, 0]

– sadclown
Jan 1 at 23:50

Wait until all threads will be stopped

– oleg.cherednik
Jan 1 at 23:51

add a comment |

First, you have to create an class declaration, that accepts required arr and implements run() method with logic.

public static class MyThread implements Runnable {



    private final int arr;

    private final Random random = new Random();



    private MyThread(int arr) {

        this.arr = arr;

    }



    @Override

    public void run() {

        try {

            while (true) {

                // wait for 2 seconds

                Thread.sleep(TimeUnit.SECONDS.toMillis(2));

                // randomly choose array element

                int i = random.nextInt(arr.length);

                // randomly choose increment or decrement an elements

                boolean add = random.nextBoolean();



                // lock WHOLE array for modification

                synchronized (arr) {

                    arr[i] = add ? arr[i] + 1 : arr[i] - 1;

                }

            }

        } catch(InterruptedException e) {

        }

    }

}

Second, you have to create an array and required number of threads for modifications.

// create an array

int arr = new int[5];



// create threads and start

for (int i = 0; i < 20; i++)

    new Thread(new MyThread(arr)).start();

That's all basically. Sure, it is possible to not lock whole array to modify only one elements, but this is another story.

edited Jan 1 at 23:37

answered Jan 1 at 21:54

oleg.cherednik

7,16021119

First, you have to create an class declaration, that accepts required arr and implements run() method with logic.

public static class MyThread implements Runnable {



    private final int arr;

    private final Random random = new Random();



    private MyThread(int arr) {

        this.arr = arr;

    }



    @Override

    public void run() {

        try {

            while (true) {

                // wait for 2 seconds

                Thread.sleep(TimeUnit.SECONDS.toMillis(2));

                // randomly choose array element

                int i = random.nextInt(arr.length);

                // randomly choose increment or decrement an elements

                boolean add = random.nextBoolean();



                // lock WHOLE array for modification

                synchronized (arr) {

                    arr[i] = add ? arr[i] + 1 : arr[i] - 1;

                }

            }

        } catch(InterruptedException e) {

        }

    }

}

Second, you have to create an array and required number of threads for modifications.

// create an array

int arr = new int[5];



// create threads and start

for (int i = 0; i < 20; i++)

    new Thread(new MyThread(arr)).start();

That's all basically. Sure, it is possible to not lock whole array to modify only one elements, but this is another story.

edited Jan 1 at 23:37

answered Jan 1 at 21:54

oleg.cherednik

7,16021119

edited Jan 1 at 23:37

answered Jan 1 at 21:54

oleg.cherednik

7,16021119

answered Jan 1 at 21:54

oleg.cherednik

7,16021119

answered Jan 1 at 21:54

oleg.cherednik

7,16021119

The final println(...) call in your main routine can be executed while worker threads still are running. Not that anybody would be able to tell by examining the program's output, but still... Are you sure that's what you wanted to show?

– Solomon Slow
Jan 1 at 23:36

I dont understand why output is [0, 0, 0, 0, 0]

– sadclown
Jan 1 at 23:50

Wait until all threads will be stopped

– oleg.cherednik
Jan 1 at 23:51

add a comment |

The final println(...) call in your main routine can be executed while worker threads still are running. Not that anybody would be able to tell by examining the program's output, but still... Are you sure that's what you wanted to show?

– Solomon Slow
Jan 1 at 23:36

I dont understand why output is [0, 0, 0, 0, 0]

– sadclown
Jan 1 at 23:50

Wait until all threads will be stopped

– oleg.cherednik
Jan 1 at 23:51

The final println(...) call in your main routine can be executed while worker threads still are running. Not that anybody would be able to tell by examining the program's output, but still... Are you sure that's what you wanted to show?

– Solomon Slow
Jan 1 at 23:36

I dont understand why output is [0, 0, 0, 0, 0]

– sadclown
Jan 1 at 23:50

Wait until all threads will be stopped

– oleg.cherednik
Jan 1 at 23:51

add a comment |

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