Question

android studio

Begin a new app and create a Java class for products with data: productName, productCode and price and use a file of objects to store product data and read back and display on screen. Do this by creating a simple form using EditTexts, buttons or ActionBar items and display output using an Alert.

Answer 1

<!— activity_main.xml -->

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <RelativeLayout

        android:id="@+id/inputView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp">

        <TextView
            android:id="@+id/nameView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Product Name : "
            android:textSize="20sp"
            android:layout_margin="10dp"
            android:textColor="#000000"
        />

        <EditText
            android:id="@+id/nameTxt"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/nameView"
            android:textSize="20sp"
            android:textColor="#000000"
            />

        <TextView
            android:id="@+id/codeView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/nameTxt"
            android:text="Product Code : "
            android:textSize="20sp"
            android:layout_margin="10dp"
            android:textColor="#000000"
            />

        <EditText
            android:id="@+id/codeTxt"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/codeView"
            android:textSize="20sp"
            android:textColor="#000000"
            />

        <TextView
            android:id="@+id/priceView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Product Price : "
            android:layout_below="@id/codeTxt"
            android:textSize="20sp"
            android:layout_margin="10dp"
            android:textColor="#000000"
            />

        <EditText
            android:id="@+id/priceTxt"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/priceView"
            android:textSize="20sp"
            android:textColor="#000000"
            android:inputType="numberDecimal"
            />

        <Button
            android:id="@+id/submit"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@id/priceTxt"
            android:text="Submit"
            android:layout_marginTop="20dp"
            android:layout_marginLeft="50dp"
            android:textSize="20sp"/>


        <Button
            android:id="@+id/show"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@id/priceTxt"
            android:layout_toRightOf="@id/submit"
            android:layout_marginTop="20dp"
            android:layout_marginLeft="20dp"
            android:text="Show Products"
            android:textSize="20sp"
            />
    </RelativeLayout>

</RelativeLayout>

<!—end of activity_main.xml -->

//MainActivity.java

package com.example.productdetails;



import android.content.DialogInterface;

import android.support.v7.app.AlertDialog;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.Toast;



import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileWriter;

import java.io.IOException;

import java.util.ArrayList;

import java.util.Scanner;



import mysimpleapps.com.productdetails.models.Product;



public class MainActivity extends AppCompatActivity implements View.OnClickListener {



    EditText nameTxt, codeTxt, priceTxt;

    Button submit, show;

    FileWriter outFile = null;



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);



        nameTxt = findViewById(R.id.nameTxt);

        codeTxt = findViewById(R.id.codeTxt);

        priceTxt = findViewById(R.id.priceTxt);

        submit = findViewById(R.id.submit);

        show = findViewById(R.id.show);



        submit.setOnClickListener(this);

        show.setOnClickListener(this);

    }



    @Override

    public void onClick(View v) {



        if(v == submit)

        {

            File file = new File(this.getFilesDir(),"products.txt");

            try {

                outFile = new FileWriter(file, true);

            } catch (IOException e) {

                Toast.makeText(getApplicationContext(),"File cannot be created or opened",Toast.LENGTH_SHORT).show();

            }



            if(nameTxt.getText().length() > 0 && codeTxt.getText().length() > 0 && priceTxt.getText().length() > 0)

            {

                Product product = new Product(nameTxt.getText().toString(),codeTxt.getText().toString(),Double.parseDouble(priceTxt.getText().toString()

                ));

                try {

                    outFile.write(product.getName()+","+product.getCode()+","+product.getPrice()+"\n");

                    Toast.makeText(getApplicationContext(),"Product data added to file",Toast.LENGTH_SHORT).show();

                } catch (IOException e) {

                    Toast.makeText(getApplicationContext(),"Product data cannot be stored",Toast.LENGTH_SHORT).show();

                }

            }else

                Toast.makeText(getApplicationContext(),"Please enter all the details for the product",Toast.LENGTH_SHORT).show();

        }else if(v == show)

        {

            try {

                if(outFile != null)

                    outFile.close();

            } catch (IOException e) {

                e.printStackTrace();

            }

            ArrayList<Product> products = new ArrayList<>();

            File file = new File(this.getFilesDir(),"products.txt");

            try {

                Scanner reader = new Scanner(file);

                while(reader.hasNextLine())

                {

                    String line = reader.nextLine();

                    if(line.length() > 0)

                    {

                        Product product = new Product();

                        int index = line.indexOf(",");

                        product.setName(line.substring(0,index));

                        index = line.indexOf(",",index+1);

                        product.setCode(line.substring(line.indexOf(",")+1,index));

                        product.setPrice(Double.parseDouble(line.substring(index+1)));

                        products.add(product);

                    }

                }



                reader.close();



                AlertDialog.Builder alert = new AlertDialog.Builder(this);

                if(products.size() > 0)

                {

                    String alertMessage = "";

                    for(int i=0;i<products.size()-1;i++)

                    {

                        alertMessage += products.get(i).toString()+"\n";

                    }



                    alertMessage += products.get(products.size()-1).toString();



                    alert.setMessage(alertMessage)

                            .setPositiveButton("OK", new DialogInterface.OnClickListener() {

                                @Override

                                public void onClick(DialogInterface dialog, int which) {

                                    dialog.cancel();

                                }

                            });



                    alert.show();



                }else

                    Toast.makeText(getApplicationContext(),"Add some products first",Toast.LENGTH_SHORT).show();



            } catch (FileNotFoundException e) {

                Toast.makeText(getApplicationContext(),"File products.txt doesn't exist",Toast.LENGTH_SHORT).show();

            }



        }

    }



    @Override

    protected void onDestroy() {

        super.onDestroy();

        try {

            if(outFile != null)

                outFile.close();

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

}

//end of MainActivity.java

Output: