amitnv / fphsdemo

Demo Android application for Forest Park High School. Used for presentation on Nov. 25, 2013

FPHSDemo

Demo Android application for Forest Park High School.
User has a bank that they can deposit and withdraw money from.
Google Play Link

Instructions to Make

1. Create a blank activity project with no navigation

• Name your MainActivity BankActivity
• If eclipse can't find your AndroidManifest.xml, highlight your project folder and hit refresh (F5)

2. Add UI Elements to your activity_bank.xml

• Add a TextView and name it balanceTextView
• Add an EditText and name it amountTextField
• Change the input type of amountTextField to include number and numberDecimal
• Add a Button and name it depositButton
• Add a Button and name it withdrawButton

3. Add Event Listeners to your buttons

• In your activity_bank.xml add the following code to your <Button /> tags
• Add android:onClick="depositClicked" to the depositButton
• Add android:onClick="withdrawClicked" to the withdrawButton
• Example Below:

    <Button
        android:id="@+id/depositButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/amountTextField"
        android:layout_below="@+id/amountTextField"
        android:layout_marginTop="15dp"
        android:onClick="depositClicked"
        android:text="Deposit" />

    <Button
        android:id="@+id/withdrawButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/depositButton"
        android:layout_alignBottom="@+id/depositButton"
        android:layout_alignRight="@+id/amountTextField"
        android:onClick="withdrawClicked"
        android:text="Withdraw" />

• Add the following code to your BankActivity.java

	public void depositClicked(View v){
		Toast.makeText(getApplicationContext(), "Deposit Made",
				   Toast.LENGTH_SHORT).show();
	}
	public void withdrawClicked(View v){
		Toast.makeText(getApplicationContext(), "Withdraw Made",
				   Toast.LENGTH_SHORT).show();
	}

• Press Cmd+Shift+O to import libraries
• Build and Run - You should now see messages when you press your buttons.

4. Create a new Class named Bank and add the following code:

/**
 * Bank
 * 
 * The Bank class is used to manage the amount of money the user has stored.
 * You can deposit, withdraw and view the bank amount with the Bank.
 */
import android.content.Context;
import android.content.SharedPreferences;

public class Bank {
	
	/*
	 * Set the amount of money in the bank
	 */
	private void setBalance(Context c, float balance){
		// Create an instance of the user preferences
		SharedPreferences userPreferences = c.getSharedPreferences("FPHS-Bank", Context.MODE_PRIVATE);
        // Create a preference editor
		SharedPreferences.Editor prefsEditor = userPreferences.edit();
		// Insert the balance into the user preferences
        prefsEditor.putFloat("balance", balance);
        // Save your changes
        prefsEditor.commit();
	}
	/*
	 * Get the amount of money in the bank
	 */
	public float getBalance(Context c){
		// Create an instance of the user preferences
		SharedPreferences userPreferences = c.getSharedPreferences("FPHS-Bank", Context.MODE_PRIVATE);
        // Request the balance from the user preferences. 
		// If the balance is not there give us zero instead
		float balance = userPreferences.getFloat("balance", 0.0f);
		// Return the balance
        return balance;
	}
	/*
	 * Deposit money into the bank
	 */
	public void deposit(Context c, float depositAmount){
		// Get the balance
		float balance = getBalance(c);
		// Increment the balance by the deposit amount
		balance += depositAmount;
		// Save the new balance
		setBalance(c,balance);
	}
	/*
	 * Withdraw Money from the bank
	 */
	public void withdraw(Context c, float withdrawAmount){
		// Get the balance
		float balance = getBalance(c);
		// Decrement the balance by the withdraw amount
		balance -= withdrawAmount;
		// Save the new balance
		setBalance(c,balance);
	}
}

5. Modify your BankActivity.java

• Add two new methods:

	/*
	 * Gets the number from the user's input
	 */
	public float getUserEntry(){
		// Find the EditText
		EditText amountTextField = (EditText) findViewById(R.id.amountTextField);
		// Parse user entry into a floating-point number
		float number = Float.valueOf(amountTextField.getText().toString());
		return number;
	}
	
	/*
	 * Update Balance Label
	 */
	private void updateUI(){
		// Make a new Bank
		Bank bank = new Bank();
		// Get the Bank balance as cast into a string
		String balance = Float.toString(bank.getBalance(getApplicationContext()));
		// Find the TextView
		TextView balanceTextView = (TextView) findViewById(R.id.balanceTextView);
		// Set the TextView's text to our balance string
		balanceTextView.setText(balance);
	}

• Update your button event listeners

	/*
	 * onClick Listener for depositButton
	 */
	public void depositClicked(View v){
		// Make a new Bank
		Bank bank = new Bank();
		// Deposit the amount the user entered from the bank
		bank.deposit(getApplicationContext(), getUserEntry());
		// Update UI to reflect new balance
		updateUI();
		// Show Deposit Notice
		Toast.makeText(getApplicationContext(), "Deposit Made",
				   Toast.LENGTH_SHORT).show();
	}
	/*
	 * onClick Listener for withdrawButton
	 */
	public void withdrawClicked(View v){
		// Make a new Bank
		Bank bank = new Bank();
		// Withdraw the amount the user entered from the bank
		bank.withdraw(getApplicationContext(), getUserEntry());
		// Update UI to reflect new balance
		updateUI();
		// Show Withdraw Notice
		Toast.makeText(getApplicationContext(), "Withdraw Made",
				   Toast.LENGTH_SHORT).show();
	}

6. Congratulations!

• Build and Run the final product.
• You should now be able to deposit and withdraw from the bank!