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I'm having some issues with the old "Cannot make a static reference to a non-static method" error in my Android program. I am creating a sand falling game (similar to the Powder Game) and I created a class called Control to create a Control Bar at the bottom of the screen with a slider for brush size (that works fine) and a button to pop up a Dialog to allow users to pick the selected element. However, when I call DemoActivity.showDialog(2) from my code, it gives the static reference to non-static error (DemoActivity is the main activity of my application). I also tried changing it to just Activity.showDialog(2), but I got exactly the same error! Please help, what am I doing wrong? Here's my code and thanks in advance:

package sand.falling.opengl; import android.content.Context; import android.util.AttributeSet; import android.util.Log; import android.view.View; import android.widget.ImageButton; import android.widget.LinearLayout; import android.widget.SeekBar; public class Control extends LinearLayout { private ImageButton control_button; private SeekBar brush_size_slider; final CharSequence[] elementslist = {"Sand", "Water", "Plant", "Wall", "Fire", "Ice", "Generator", "Oil", "Magma", "Stone", "C4"}; public Control(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void onFinishInflate() { control_button = (ImageButton) findViewById(R.id.element_picker_button); brush_size_slider = (SeekBar) findViewById(R.id.brush_size_slider); control_button.setOnClickListener ( new OnClickListener() { public void onClick(View v) { //THIS DOESN'T WORK!!!! DemoActivity.showDialog(2); //Run the element picker dialog } } ); control_button.setImageResource(R.drawable.palette); brush_size_slider.setOnSeekBarChangeListener ( new SeekBar.OnSeekBarChangeListener() { public void onProgressChanged(SeekBar seekbar, int progress, boolean fromTouch) { int p = 32 * progress/100; DemoActivity.setBrushSize(p); Log.v("DemoActivity", "size:" + p); } public void onStartTrackingTouch(SeekBar seekbar) {} public void onStopTrackingTouch(SeekBar seekbar) {} } ); brush_size_slider.setProgress((int)400/32); } }

EDIT: I fixed it by adding the following to my Control.java code:

public class Control extends LinearLayout { private DemoActivity activity; ... public void setActivity(DemoActivity act) { activity = act; } ... //Set a click listener for the button which should pop up element picker dialog when clicked control_button.setOnClickListener ( new OnClickListener() { public void onClick(View v) { activity.showDialog(2); //Run the element picker dialog } } ); }

And then calling control.setActivity(this); from my onResume section of DemoActivity.java! Hope it helps those of you with similar issues!!

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You have to call showDialog on a DemoActivity instance, NOT on the class itself. The only time you can call ClassName.methodName() is if the method is defined as static. showDialog is not a static method.

To fix this, you either need to instantiate a new DemoActivity or get an existing one, then call showDialog on that.

Edit: If you already have a DemoActivity instance when you instantiate this Control object, perhaps the following modification will work:

public class Control extends LinearLayout { ... // add an Activity instance private Activity activity; // set the Activity in your constructor public Control(Context context, AttributeSet attrs, Activity activity) { super(context, attrs); this.activity = activity; } @Override protected void onFinishInflate() { ... // Use the instance activity here activity.showDialog(2); ... } }
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Ah, I think I get it. How would I go about getting a reference to a specific instance of the DemoActvity class. AFAIK, I don't create one myself, Android does it automatically when the user runs my app, so how do I reference it? Thanks for the rapid answer btw!
Hmm, not sure, I haven't done any Android development yet. I'll take a look for DemoActivity documentation. Does DemoActivity have a instance() or getInstance() method? If so, that might be what you need.
Well, DemoActivity is a class that I created that extends the general Activity class contained in the basic Android code. I looked up the documentation for Activity in Android, and there is a function called getInstanceCount(), but nothing like just instance() or getInstance().
If you've got an existing DemoActivity instance outside of the Control class, you could probably pass it into the Control constructor, save it as a attribute of Control, then use it down in onFinishInflate().
I tried your edit, and it fixed the error, however when I run my app in the emulator and click on the button, it crashes with a NullPointerException at Line 42 of Control.java: activity.showDialog(2); //Run the element picker dialog I'm not quite sure why.
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if the create is called by ANDROID, so you do not create the instance, just put into the create mShowDialog=this or mShowDialog=pShowDialog

in other words - have the create save the instance value also you can add a public get to get that instance value. Then you can access the instance function through the abstract by interceding the getter:

ABSTRACTCLASS.getInstance().applyFunction();
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