我有个明显的错误。第一次还不错。但我把它改为“public class color\u dia extends dialog implements view.onclicklistener”，它是清单文件中color\u dia的红线。
当我点击一个与颜色直径有关的按钮时。出现错误“java.lang.runtimeexception:无法示例化活动组件信息”
我该怎么办？

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);   
    }
}