activity error in manifest file in android studio

Question

I have a manifest error. It was fine at first time. But i chagned it to "public class color_dia extends Dialog implements View.OnClickListener" and it was red line on color_dia in manifest file.

when i click a button related to color_dia. it makes error "java.lang.RuntimeException: Unable to instantiate activity ComponentInfo"

what should i do?

import android.app.Dialog;

import android.content.Context;

import android.os.Bundle;

import android.view.View;

import static android.graphics.Color.rgb;


    public class color_dia extends Dialog implements View.OnClickListener {
    private MainActivity mActivity;

    public color_dia(Context context) {
        super(context);
        mActivity = (MainActivity) context;
    }

    public color_dia(Context context, int themeResId) {
        super(context, themeResId);
        mActivity = (MainActivity) context;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setTitle("Pick Line Color");
        setContentView(R.layout.color_dia);   
    }
}

Answer 1

You cannot launch a Dialog using startActivity() or startActivityForResult(). You can only launch activities (class that extends Activity). A Dialog is shown in an Activity by calling showDialog() (or use DialogFragment). Please read about the difference between Dialog and Activity in the Android documentation or find a suitable tutorial to follow.