Adding Exercise 5.5 Java8 In Action

Author: sanketgupta07

src/com/java8in/action/ch5/TestClass.java

@@ -0,0 +1,72 @@
+/**
+ * 
+ */
+package com.java8in.action.ch5;
+
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * @author Sanket Gupta
+ *
+ */
+public class TestClass {
+
+/**
+ * @param args
+ */
+public static void main(String[] args) {
+Trader raoul = new Trader("Raoul", "Cambridge");
+Trader mario = new Trader("Mario", "Milan");
+Trader alan = new Trader("Alan", "Cambridge");
+Trader brain = new Trader("Brain", "Cambridge");
+
+List<Transaction> transactions = Arrays.asList(
+new Transaction(brain, 2011, 300),
+new Transaction(raoul, 2012, 1000),
+new Transaction(raoul, 2011, 400),
+new Transaction(mario, 2012, 710),
+new Transaction(mario, 2012, 700),
+new Transaction(alan, 2012, 950));
+
+
+//	1. Find all transactions in the year 2011 and sort them by value (small to high).
+System.out.println("Answer 1:");
+transactions.stream().filter( t->t.getYear()==2011).sorted((t1,t2)->Integer.compare(t1.getValue(), t2.getValue())).forEach(t3-> System.out.println(t3));
+transactions.stream().filter( t->t.getYear()==2011).sorted(Comparator.comparing(Transaction::getValue)).forEach(t3-> System.out.println(t3));//.collect(Collectors.toList());
+
+//	2. What are all the unique cities where the traders work?
+System.out.println("Answer 2:");
+transactions.stream().map(t->t.getTrader().getCity()).distinct().forEach(c->System.out.println(c));
+
+//	3. Find all traders from Cambridge and sort them by name.
+System.out.println("Answer 3:");
+transactions.stream().filter(t->t.getTrader().getCity()=="Cambridge").map(t->t.getTrader()).sorted(Comparator.comparing(Trader::getName)).distinct().forEach(trader->System.out.println(trader));//.collect(Collectors.toList());
+
+//	4. Return a string of all traders's names sorted alphabetically.
+System.out.println("Answer 4:");
+//	String names=transactions.stream().map(tx->tx.getTrader().getName()).distinct().sorted().reduce("",(n1,n2)->n1+n2);
+String names=transactions.stream().map(tx->tx.getTrader().getName()).distinct().sorted().collect(Collectors.joining());
+System.out.println(names);
+//	transactions.stream().map(tx->tx.getTrader().getName()).sorted().collect(joining());
+
+//	5. Are any traders based in Milan?
+System.out.println("Answer 5:");
+Boolean isMialBased=transactions.stream().anyMatch(transaction -> transaction.getTrader().getCity().equals("Milan"));
+System.out.println(isMialBased);
+
+//	6. Print all transactions' values from the traders living in Cambridge.
+System.out.println("Answer 6:");
+transactions.stream().filter(t->t.getTrader().getCity()=="Cambridge").map(Transaction::getValue).distinct().forEach(tradeValue->System.out.println(tradeValue));
+
+//	7. What's the highest value of all the transactions?
+System.out.println("Answer 7:");
+System.out.println(transactions.stream().map(tx->tx.getValue()).max(Comparator.comparing(Integer::intValue)));
+//	8. Find the transaction with the smallest value. 
+System.out.println("Answer 8:");
+System.out.println(transactions.stream().min(Comparator.comparing(Transaction::getValue)));
+}
+
+}

src/com/java8in/action/ch5/Trader.java

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+/**
+ * 
+ */
+package com.java8in.action.ch5;
+
+/**
+ * @author Sanket Gupta
+ *
+ */
+public class Trader {
+
+private final String name;
+private final String city;
+/**
+ * @param name
+ * @param city
+ */
+public Trader(String name, String city) {
+this.name = name;
+this.city = city;
+}
+/**
+ * @return the name
+ */
+public String getName() {
+return name;
+}
+/**
+ * @return the city
+ */
+public String getCity() {
+return city;
+}
+/* (non-Javadoc)
+ * @see java.lang.Object#toString()
+ */
+@Override
+public String toString() {
+return "Trader [name=" + name + ", city=" + city + "]";
+}
+
+}

src/com/java8in/action/ch5/Transaction.java

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+/**
+ * 
+ */
+package com.java8in.action.ch5;
+
+/**
+ * @author Sanket Gupta
+ *
+ */
+public class Transaction {
+
+private final Trader trader;
+private final int year;
+private final int value;
+/**
+ * @param trader
+ * @param year
+ * @param value
+ */
+public Transaction(Trader trader, int year, int value) {
+this.trader = trader;
+this.year = year;
+this.value = value;
+}
+/**
+ * @return the trader
+ */
+public Trader getTrader() {
+return trader;
+}
+/**
+ * @return the year
+ */
+public int getYear() {
+return year;
+}
+/**
+ * @return the value
+ */
+public int getValue() {
+return value;
+}
+
+/* (non-Javadoc)
+ * @see java.lang.Object#toString()
+ */
+@Override
+public String toString() {
+return "Transaction [trader=" + trader + ", year=" + year + ", value=" + value + "]";
+}
+
+}