Really n00bish question...

So I figure this has to be possible but I don't know how to do it.

If it makes any difference, I'm coding Java for Android.

First post here so go easy :)

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I was assigned to write a program to solve a real world problem in one of my classes. It's due next Monday (one week). The only hangup I have left to solve is possibly the easiest.

I have one package, com.xxx.android.yyy, and in that package I have private class 1. In that private class, I have a public void, and in that there are a few "if" statements:

Code:

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public void onLocationChanged(Location location) {
                    if(location!=null){
                            if(location.hasSpeed()){
                                    mySpeed = location.getSpeed();
                                    if(mySpeed>maxSpeed)
                                            maxSpeed = mySpeed;
                                    tv.setText("\nCurrent speed: " + mySpeed*2.2369 + " mph, Max speed: " + maxSpeed*2.2369 + " mph");
                                    if(mySpeed>=limitSpeed){
                                            //***Need to call public class from pkg com.xxx.android.zzz***
                                    }

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Within that if statement [if(mySpeed>=limitSpeed)], I need to call a public class from package com.xxx.android.zzz

How do I do that?


EDIT: I think this might be in the wrong forum. I'm sorry if it is. In the event that I'm right, feel free to move it to the appropriate place :)

Private classes should be only used in nested classes. There is no way to instantiate a private class unless it's nested in a public class.

Quote:

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I need to call a public class from package com.xxx.android.zzz

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Not sure about your question. Is the public class you want to "call" in the package ...zzz
or is the "calling" code in the ...zzz package?
By "calling" do you mean use new to create a new instance of the class?
Or do you mean calling a method in the class?
Then is the question: How do I get a reference to the class so I can call one of its methods?

Quote:

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Originally Posted by Lil_Aziz1

Private classes should be only used in nested classes. There is no way to instantiate a private class unless it's nested in a public class.

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It is. I only posted a snippet of the code.

Quote:

---

Originally Posted by Norm

Not sure about your question. Is the public class you want to "call" in the package ...zzz
or is the "calling" code in the ...zzz package?
By "calling" do you mean use new to create a new instance of the class?

---

The class I need to use from the zzz package plays a very important role in the overall program.

Unfortunately I need it to perform that role in the private class within the yyy package, when mySpeed is greater than limitSpeed.

here:

Code:

---

public class AirplaneChange extends Activity {
        public void method() {
                Context context = getApplicationContext();
               
                boolean isEnabled = Settings.System.getInt(context.getContentResolver(), Settings.System.AIRPLANE_MODE_ON, 0)== 1;
               
                Settings.System.putInt(context.getContentResolver(), Settings.System.AIRPLANE_MODE_ON, isEnabled ? 0 : 1);

---

I need that to do it's thing when mySpeed > limitSpeed.

In that case, the same way you would reference any other class:

Code:

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//Assume private class is called ActionListener.
//Assume constructor takes no paramaters.

ActionListener listener = new ActionListener();

//Assume there is at least one method that takes no paramaters
listener.[U]method[/U]();

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Would that private be from my first package, yyy?

Only if the public class that has the nested private class is in the package yyy. Example:

Code:

---

package yyy;

public class A {
    ...
    private class B {
          ...
    }
}

---

Both classes (A and B) are in the package yyy because A is in the package yyy and B is part of A. I hope that makes sense.

Yes they are and yes it does.

From the above example, the one with ActionListener, would I just throw the public void from my public class AirplaneChange in post #5 after the listener.method(); ?

if you put listener.method() before the void method, wouldn't it look like this?

Code:

---

package yyy;
public class A {
    ActionListener listener = new ActionListener(); //discouraged.
    listener.method(); //Pretty sure this will give you java.lang.Error Exception
    public void publicMethod() {
        ...
    }
    private class ActionListener {
        public void method() {
            ...
        }
    }
}

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Perhaps you could attach zip file and give us a couple of places to look? I'm not really visualizing your problem at this point. All I know is it has to do with package structure, and that's not really helping me. If for whatever reason you can't attach the code, I'd understand, but it would make things easier :)

Quote:

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I need it to perform that role in the private class within the yyy package

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What does "perform that role" mean?
The code in a private class should be able to create new instances of public classes.

Have you tried coding yet? Do you get errors? Given an error, we'd have something to work with. All this theoretical talk is hard to follow. Let's have code.

Quote:

---

Originally Posted by Singing Boyo

Perhaps you could attach zip file and give us a couple of places to look? I'm not really visualizing your problem at this point. All I know is it has to do with package structure, and that's not really helping me. If for whatever reason you can't attach the code, I'd understand, but it would make things easier :)

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I was hesitant to post code but I suppose I can.

Here you go... this was package yyy in my first post.

Code:

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package com.ryan.android.cellsafe;

import android.app.Activity;
import android.os.Bundle;
import android.provider.Settings;
import android.provider.Settings.System;
import android.widget.TextView;
import android.content.Context;
import android.content.ContentResolver;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;

public class CellSafe extends Activity {
   
   
    private TextView tv;
    private LocationManager lm;
    private LocationListener ll;
    double mySpeed, maxSpeed, limitSpeed;
   
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        tv = new TextView(this);
        setContentView(tv);
       
        maxSpeed = mySpeed = 0;
        limitSpeed = 7.8232;
       
        lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        ll = new SpeedoActionListener();
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, ll);
    }
   
    private class SpeedoActionListener implements LocationListener {
       
        @Override
        public void onLocationChanged(Location location) {
            if(location!=null){
                if(location.hasSpeed()){
                    mySpeed = location.getSpeed();
                    if(mySpeed>maxSpeed)
                        maxSpeed = mySpeed;
                    tv.setText("\nCurrent speed: " + mySpeed*2.2369 + " mph, Max speed: " + maxSpeed*2.2369 + " mph");
                    if(mySpeed>=limitSpeed){
                       
                        //***AREA IN QUESTION***
                       
                    }
                   
                            }
                       
                        }
                    }
                                 
       
       
          @Override
          public void onProviderDisabled(String provider) {
              //TODO Auto-generated method stub
             
          }
         
          @Override
          public void onProviderEnabled(String provider) {
              //TODO Auto-generated method stub
          }
         
          @Override
          public void onStatusChanged(String provider, int status, Bundle extras) {
              //TODO Auto-generated method stub
             
        }

                 
    }
}

---

And this is package zzz

Code:

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package com.ryan.android.airplanechange;

import android.provider.Settings;
import android.app.Activity;
import android.content.Context;

public class AirplaneChange extends Activity {
    public void method() {
        Context context = getApplicationContext();
       
        boolean isEnabled = Settings.System.getInt(context.getContentResolver(), Settings.System.AIRPLANE_MODE_ON, 0) == 1;
       
        Settings.System.putInt(context.getContentResolver(), Settings.System.AIRPLANE_MODE_ON, isEnabled ? 0 : 1);
    }


}

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As you can see, I've marked the area in question in the CellSafe package. AirplaneChange switches Airplane Mode on. I need that to happen when mySpeed is greater than or equal to limitSpeed.

Right. That really does help. I thought it was what you meant, but it would have been just as hard to explain without code as it was to understand it (and I still wasn't sure what you meant originally - code helps)

At the beginning of the CellSafe method, with the imports, (preferably before or after) add an import for com.ryan.android.airplanechange.AirplaneChange. At the area in question, just use AirplaneChange as you would any other class. In code:

Code:

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//import
import com.ryan.android.airplanechange.AirplaneChange;

//at area in question
AirplaneChange airChange = new AirplaneChange();
//register airChange with whatever you need to
//I don't know android, but judging from the interface name (Activity)
//you'd queue it with something to be run ASAP

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Hopefully this helps.

Singing Boyo

P.S. Change the package name. com.ryan.android.airplanechange is just unwieldy and long... find an abbreviation, or a different package name based on other contents. If it's the only class in the package, you may want to move it.

Just one more piece of advice, if you use some package only once, instead of bloating up your imports, you can use it directly:

Code:

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//some method that needs keyboard input
void someMethod() {
  java.util.Scanner sc = new java.util.Scanner(System.in);
}

---

Functionallity is of course the same as just importing the Scanner class, it's only a matter of style and preference.