Getting java.lang.ClassCastException in my app

Question

I am making an e-commerce app and I am making Cart for the app here is my code

Controller.java

package com.example.android.namkeen;

import android.app.Application;

import java.util.ArrayList;

/**
 * Created by SONY on 02-10-2016.
 */
public class Controller extends Application
{
    private ArrayList<ModelProducts> myproducts = new ArrayList<ModelProducts>();
    private ModelCart myCart = new ModelCart();
    public ModelProducts getProducts(int pPosition){
        return myproducts.get(pPosition);
    }
    public void  setProducts(ModelProducts products){
        myproducts.add(products);
    }
    public ModelCart getCart(){
        return myCart;
    }
    public int  getProductArraylistsize(){
        return myproducts.size();
    }
}

ModelCart.java

package com.example.android.namkeen;

import java.util.ArrayList;

public class ModelCart {
    private ArrayList<ModelProducts> cartItems = new ArrayList<ModelProducts>();
    public ModelProducts getProducts(int position){
        return cartItems.get(position);
    }
    public void setProducts(ModelProducts Products){
        cartItems.add(Products);
    }
    public int getCartsize(){

        return cartItems.size();
    }
    public boolean CheckProductInCart(ModelProducts aproduct){
        return cartItems.contains(aproduct);
    }
}

ModelProducts.java

package com.example.android.namkeen;

/**
 * Created by SONY on 02-10-2016.
 */
public class ModelProducts {
    private String productName;
    private String productDesc;
    private int productPrice;
    public ModelProducts(String productName,String productDesc,int productPrice){
        this.productName = productName;
        this.productDesc = productDesc;
        this.productPrice = productPrice;
    }

    public String getProductName(){
        return productName;
    }

    public String getProductDesc(){
        return productDesc;
    }

    public int getProductPrice(){
        return productPrice;
    }
}

and this is the main activity in which I am making a custom view and I am using controller class to add the products

 package com.example.android.namkeen;

    import android.content.Intent;
    import android.graphics.Typeface;
    import android.os.Bundle;
    import android.support.v7.app.ActionBar;
    import android.support.v7.app.AppCompatActivity;
    import android.util.Log;
    import android.util.TypedValue;
    import android.view.View;
    import android.widget.Button;
    import android.widget.LinearLayout;
    import android.widget.TextView;
    import android.widget.Toast;


    public class CartMain extends AppCompatActivity {
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);







            final LinearLayout layout = (LinearLayout)findViewById(R.id.linearMain);
            final Button btn = (Button)findViewById(R.id.second);
            final Controller ct = (Controller) getApplicationContext();//getting error in this line 
            ModelProducts products = null;
            int Price=30;
            products = new ModelProducts("Plain Maath", "Plain salted \n big sized mathri", Price);
            ct.setProducts(products);
         /*   for(int i= 1; i<=7;i++)
            {
                int Price = 15+ i;
                products = new ModelProducts("Product Item" +i, "Description"+i, Price);
                ct.setProducts(products);
            }*/
            int productsize = ct.getProductArraylistsize();
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ActionBar.LayoutParams.WRAP_CONTENT, ActionBar.LayoutParams.WRAP_CONTENT);
            for (int j=0;j< productsize;j++){
                String pName = ct.getProducts(j).getProductName();
                int pPrice = ct.getProducts(j).getProductPrice();
                String desc = ct.getProducts(j).getProductDesc();
                LinearLayout la = new LinearLayout(this);
                la.setOrientation(LinearLayout.HORIZONTAL);

                LinearLayout la1 = new LinearLayout(this);
                la1.setOrientation(LinearLayout.VERTICAL);





                TextView tv = new TextView(this);
                tv.setText(" " + pName + " ");
                tv.setTypeface(null, Typeface.BOLD);
                tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, 22F);
                la1.addView(tv);


                TextView des = new TextView(this);
                des.setText(" " + desc + " ");

                la1.addView(des);


                TextView tv1 = new TextView(this);
                tv1.setText(" "+"Rs"+pPrice+"/250gm"+" ");
                la1.addView(tv1);
                la.addView(la1);

                final Button btn1 = new Button(this);
                btn1.setId(j+1);
                btn1.setText("Add to Cart");
                btn1.setLayoutParams(params);
                final int index = j;
                btn1.setOnClickListener(new View.OnClickListener()
                {
                    public void onClick(View v) {
    // TODO Auto-generated method stub
                        Log.i("TAG", "index:"+index);
                        ModelProducts productsObject = ct.getProducts(index);
                        if(!ct.getCart().CheckProductInCart(productsObject)){
                            btn1.setText("Item Added");
                            ct.getCart().setProducts(productsObject);
                            Toast.makeText(getApplicationContext(), "New CartSize:" +ct.getCart().getCartsize(),Toast.LENGTH_LONG).show();
                        }else{
                            Toast.makeText(getApplicationContext(), "Products"+(index+1)+"Already Added",Toast.LENGTH_LONG ).show();
                        }
                    }
                });
                la.addView(btn1);
                layout.addView(la);
            }
            btn.setOnClickListener(new View.OnClickListener()
            {
                @Override
                public void onClick(View v) {
    // TODO Auto-generated method stub
                    Intent in = new Intent(getBaseContext(),Screen2.class);
                    startActivity(in);
                }
            });
        }
    }

This is the code which will work when checkout button will be clicked in the cart activity Screen2.java

package com.example.android.namkeen;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;

/**
 * Created by SONY on 02-10-2016.
 */
public class Screen2 extends AppCompatActivity
{
    /* (non-Javadoc)
    * @see android.app.Activity#onCreate(android.os.Bundle) */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.screen2);




        TextView showCartContent = (TextView)findViewById(R.id.showcart);
        final Controller ct = (Controller)getApplicationContext();
        final int CartSize = ct.getCart().getCartsize();
        String show = "";
        for(int i=0;i<CartSize;i++){
            String pName = ct.getCart().getProducts(i).getProductName();
            int  pPrice = ct.getCart().getProducts(i).getProductPrice();
            String pDisc = ct.getCart().getProducts(i).getProductDesc();
            show += "Product Name:"+pName+" "+"Price : "+pPrice+""+"Discription : "+pDisc+""+    "-----------------------------------";
        }
        showCartContent.setText(show);
    }
}

I am doing everything correct but when I am running this code it is giving this exception error

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.namkeen/com.example.android.namkeen.CartMain}: java.lang.ClassCastException: android.app.Application cannot be cast to com.example.android.namkeen.Controller

Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.example.android.namkeen.Controller at com.example.android.namkeen.CartMain.onCreate(CartMain.java:32)

I am not able to understand what should I do where I should change my code please help thanks in advance

Answer 1

You should use getApplication() instead of getApplicationContext() when you want to retrieve the Application instance.

Also hope you declared the Controller class as the Application class in your manifest file.

Also it is not the best idea to subclass your Application class just to store data in it... You should use a singleton class instead.