variable not available despite public method

Question

The float targetVolume in created in a public void method, but cannot be resolved in another public void method...

    scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
        public void run() {
            float x = (float) Math.random();
            if (x < 0.5){
                float targetVolume = 0;
            } else {
                float targetVolume = 1;
            }

            scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
                public void run() {
                    if (targetVolume.equals (1)){
                        mp.setVolume(startingVolume+volumeIncrement, startingVolume+volumeIncrement);
                    } else {
                        mp.setVolume(startingVolume-volumeIncrement, startingVolume-volumeIncrement);
                    }
                }
            }, 0, 1, TimeUnit.SECONDS);
        }
    }, 0, 5, TimeUnit.SECONDS);

How can I fix this?

EDIT: I can solve the problem by adding the final modifier to the float:

        scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
        public void run() {
            float x = (float) Math.random();
            final float targetVolume=(x < 0.5)?0:1;

            scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
                public void run() {
                    if (targetVolume >startingVolume){
                        startingVolume = startingVolume+volumeIncrement;
                        mp.setVolume((startingVolume), (startingVolume));
                        }
                    else if (targetVolume < startingVolume){
                        startingVolume = startingVolume-volumeIncrement;
                        mp.setVolume((startingVolume), (startingVolume));
                        }              
                }
            }, 0, 1, TimeUnit.SECONDS);
        }
    }, 0, 5, TimeUnit.SECONDS);

However, does the final float targetVolume now hold the same value (a zero or a 1) each time the task is run? I need this value to change randomly...

http://stackoverflow.com/questions/2088299/what-is-the-difference-between-local-and-instance-variables-in-java — user1339772, Jan 31 '14 at 17:08

score 0 · Accepted Answer · answered Jan 31 '14 at 16:57

0

You have declared it locally to that method

cheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
    public void run() {
        float x = (float) Math.random();
        if (x <0.5){
            float targetVolume =0;}

declare it as a member variable to the class to have class scope. This means to define it anywhere outside of a method (usually just before onCreate() for an Activity).

Read about Java variable scope

answered Jan 31 '14 at 16:57

codeMagic

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This DID make the float available, HOWEVER does the final float targetVolume now hold the same value (a zero or a 1) each time the task is run? I need this value to change randomly... – Pete Jan 31 '14 at 23:36
It doesn't need to be `final` since it is a member variable. Don't make it `static` and you should be fine – codeMagic Jan 31 '14 at 23:50
The variable needs to be created inside that method in order for it to change at set time intervals though... – Pete Feb 01 '14 at 00:11
No, it just needs to be initialized there (given a value). Declare it as a member variable (`float targetVolume;`) – codeMagic Feb 01 '14 at 00:24

score 0 · Answer 2 · answered Jan 31 '14 at 17:37

Change to:

scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
    public void run() {
        float x = (float) Math.random();
        final float targetVolume=(x < 0.5)?0:1;

        scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
            public void run() {
                if (targetVolume==1){
                    mp.setVolume(startingVolume+volumeIncrement, startingVolume+volumeIncrement);
                } else {
                    mp.setVolume(startingVolume-volumeIncrement, startingVolume-volumeIncrement);
                }
            }
        }, 0, 1, TimeUnit.SECONDS);
    }
}, 0, 5, TimeUnit.SECONDS);

This DID make the float available, HOWEVER does the final float targetVolume now hold the same value (a zero or a 1) each time the task is run? I need this value to change randomly... — Pete, Jan 31 '14 at 23:36

variable not available despite public method

2 Answers2