Add Ch 14 practice problems

Author: neha-peddinti

src/com/codefortomorrow/advanced/chapter14/practice/Average.java

@@ -0,0 +1,31 @@
+package com.codefortomorrow.advanced.chapter14.practice;
+import java.io.*;
+
+/*
+The file “numbers.txt” has 100 random numbers
+(one on each line). Use file i/o to find the
+average of these numbers. Write “Average: ”
+and display the average on the next (101st)
+line of the file.
+
+Hint: Just like BufferedReader and FileReader,
+there are BufferedWriter and FileWriter classes
+that allow you to add full words to files,
+instead of just bytes. You should do a quick
+Google search to explore these classes first,
+but just to get you started:
+
+new FileWriter(“fileName.txt”, true)
+
+will create an instance of FileWriter, and
+the “true” puts it in append mode, so you
+start writing to the end of the file instead
+of writing over the existing content from the beginning.
+*/
+
+public class Average {
+    public static void main(String[] args) {
+
+        // Add code here.
+    }
+}

src/com/codefortomorrow/advanced/chapter14/practice/Bank.java

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+package com.codefortomorrow.advanced.chapter14.practice;
+
+/*
+Create a class called BankAccount (a separate
+class from your main program) that contains a
+private “balance” attribute for the amount of
+money in the account.
+
+The user should be able to set the original
+balance upon initialization (through the constructor).
+The class should have deposit and withdraw methods
+that add and subtract money from the account.
+There should also be a getter method to access
+the balance, since the attribute is private.
+
+Create at least 2 instances of BankAccount.
+Deposit, withdraw, and display the final balance of each.
+
+Create a NotEnoughMoneyException class that is a
+checked exception. The withdraw method should throw
+this exception if the user tries to withdraw an
+amount that is greater than their current balance.
+Handle this exception by displaying the difference
+between the balance and the amount to be withdrawn,
+and do this exception handling in the main program
+where you have created instances of BankAccount.
+*/
+
+public class Bank {
+    
+    public static void main(String[] args) {
+
+        // Your code here.
+    }
+}
+
+// Add other classes here.

src/com/codefortomorrow/advanced/chapter14/practice/numbers.txt

@@ -0,0 +1,100 @@
+35
+94
+16
+38
+82
+87
+52
+60
+86
+59
+72
+7
+60
+56
+63
+11
+67
+77
+67
+82
+28
+13
+100
+92
+85
+69
+75
+6
+83
+100
+76
+51
+13
+84
+59
+30
+21
+72
+15
+28
+15
+95
+87
+61
+80
+22
+45
+9
+73
+85
+85
+2
+90
+75
+60
+80
+91
+21
+80
+41
+82
+27
+48
+43
+37
+52
+78
+21
+54
+20
+15
+49
+42
+89
+63
+24
+10
+62
+44
+63
+51
+34
+36
+21
+2
+49
+64
+77
+34
+80
+7
+83
+51
+46
+11
+25
+59
+96
+21
+65

src/com/codefortomorrow/advanced/chapter14/solutions/Average.java

@@ -0,0 +1,50 @@
+package com.codefortomorrow.advanced.chapter14.solutions;
+import java.io.*;
+
+/*
+The file “numbers.txt” has 100 random numbers
+(one on each line). Use file i/o to find the
+average of these numbers. Write “Average: ”
+and display the average on the next (101st)
+line of the file.
+
+Hint: Just like BufferedReader and FileReader,
+there are BufferedWriter and FileWriter classes
+that allow you to add full words to files,
+instead of just bytes. You should do a quick
+Google search to explore these classes first,
+but just to get you started:
+
+new FileWriter(“fileName.txt”, true)
+
+will create an instance of FileWriter, and
+the “true” puts it in append mode, so you
+start writing to the end of the file instead
+of writing over the existing content from the beginning.
+*/
+
+public class Average {
+    public static void main(String[] args) {
+        File file = new File("numbers.txt");
+        
+        // try with resources block, which closes streams automatically
+        try(BufferedReader in = new BufferedReader(
+            new FileReader(file)); BufferedWriter out = new BufferedWriter(
+            new FileWriter(file, true))) {
+
+            // read the numbers (String input) and find average
+            double average = 0;
+            String contentLine = in.readLine();
+            while (contentLine != null) {
+                average += Integer.parseInt(contentLine);
+                contentLine = in.readLine();
+            }
+            average /= 100.;
+
+            // append average to end of file
+            out.write("Average: " + average);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}

src/com/codefortomorrow/advanced/chapter14/solutions/Bank.java

@@ -0,0 +1,86 @@
+package com.codefortomorrow.advanced.chapter14.solutions;
+
+/*
+Create a class called BankAccount (a separate
+class from your main program) that contains a
+private “balance” attribute for the amount of
+money in the account.
+
+The user should be able to set the original
+balance upon initialization (through the constructor).
+The class should have deposit and withdraw methods
+that add and subtract money from the account.
+There should also be a getter method to access
+the balance, since the attribute is private.
+
+Create at least 2 instances of BankAccount.
+Deposit, withdraw, and display the final balance of each.
+
+Create a NotEnoughMoneyException class that is a
+checked exception. The withdraw method should throw
+this exception if the user tries to withdraw an
+amount that is greater than their current balance.
+Handle this exception by displaying the difference
+between the balance and the amount to be withdrawn,
+and do this exception handling in the main program
+where you have created instances of BankAccount.
+*/
+
+public class Bank {
+    
+    public static void main(String[] args) {
+        BankAccount account1 = new BankAccount(500);
+        BankAccount account2 = new BankAccount(1000);
+
+        account1.deposit(200);
+        withdraw(account1, 300);
+        System.out.println("Account 1: " + account1.getBalance());
+
+        account2.deposit(200);
+        withdraw(account2, 1500);
+        System.out.println("Account 2: " + account2.getBalance());
+    }
+
+    public static void withdraw(BankAccount account, int amount) {
+        try {
+            account.withdraw(amount);
+        } catch (NotEnoughMoneyException e) {
+            int diff = Math.abs(amount - account.getBalance());
+            System.out.println(e.toString());
+        }
+    }
+}
+
+
+class BankAccount {
+    private int balance;
+
+    public BankAccount(int balance) {
+        this.balance = balance;
+    }
+
+    public void deposit(int amount) {
+        balance += amount;
+    }
+
+    public void withdraw(int amount) throws NotEnoughMoneyException {
+        if(amount > balance)
+            throw new NotEnoughMoneyException(
+                "Bank balance is short $" + Math.abs(balance - amount));
+        balance -= amount;
+    }
+
+    public int getBalance() {
+        return balance;
+    }
+}
+
+
+class NotEnoughMoneyException extends Exception {
+
+    public NotEnoughMoneyException() {}
+
+    public NotEnoughMoneyException(String message) {
+        super(message);
+    }
+}