equals method

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What will be the result of the following code execution? import java.util.*; class Employee { private String name; public Employee(String name) { this.name = name; } public String toString() { return name; } public boolean equals(Object obj) { HashCodeTest.count++; if (obj == null) return false; if (obj.getClass() != getClass()) return false; Employee emp = (Employee) obj; if (this.name == emp.name) { return true; } return false; } public int hashCode(){ return name.hashCode(); } } public class HashCodeTest { static int count = 0; public static void main(String[] args) { Map employees = new HashMap(); employees.put(new Employee("Joe"), new Integer("1")); employees.put(new Employee("Chandler"), new Integer("2")); employees.put(new Employee("Chandler"), new Integer("2")); employees.put(new Employee("Ross"), new Integer("3")); Iterator iterator = employees.keySet().iterator(); while (iterator.hasNext()) { System.out.println(iterator.next()); } System.out.println(count); } } P.S. For experts - hashtags of the lines "Joe", "Chandler" and "Ross" are different.

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Which of the following statements are true given the following code: String a = new String("hello"); String b = new String(a); String c = a; char[] d = { 'h', 'e', 'l', 'l', 'o' };

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Select all the statements that are correct regarding the following code: public class TestClazz { public static void main(String[] args) { final long Byte = 0; // 1 if ( Byte.equals(0) ) { // 2 System.out.print("=="); } else { System.out.print("!="); } } }

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What will be the output of the following code? class Main { public static void main (String[] args) { String str = "hello"; StringBuffer sb = new StringBuffer(str); System.out.print(sb.equals(str) + "," + str.equals(sb)); } }

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What will be displayed ? public class Tst { public static class Foo { private final Integer x; public Foo(Integer x) { this.x = x; } public boolean equals(Foo f) { return f.x.equals(this.x); } public int hashCode() { return x.intValue(); } } public static void main(String[] args) { final Foo f1 = new Foo(1); final Foo f2 = new Foo(1); final Set<Foo> set = new HashSet<Foo>(); set.add(f1); set.add(f2); System.out.println(set.size()); } }

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What will be printed after execution of this code? class User { private String name; public User( String name ) { this.name = name; } public boolean equals( Object obj ) { User user = (User) obj; return user.name.equals( name ); } public String toString() { return name; } } class Foo { public static void main(String...arguments) { //1 User user1 = new User( "John" ); User user2 = new User( "Bill" ); User user3 = new User( "John" ); Set<User> userSet = new HashSet<User>(); userSet.add( user1 ); userSet.add( user2 ); userSet.add( user3 ); //2 System.out.println( "Count of users: " + userSet.size() ); //3 } }

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What will be the output of the following program? class Person { public String name; public int age; public Person(String name, int age) { this.name = name; this.age = age; } public boolean equals(Object obj) { return obj instanceof Person && this.age == ((Person)obj).age && this.name.equals(((Person)obj).name); } } public class Quizful { public static void main(String[] args){ Person p1 = new Person(null, 10); Person p2 = new Person("Alex", 22); System.out.println(p1.equals(p2)); } }

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What will be written to the console by the following code: 01: public class Clazz { 02: public static void main(String[] args) { 03: Integer integer = new Integer(1024); 04: Long aLong = new Long(1024); 05: if (integer.equals(aLong)) 06: System.out.println("eq"); 07: if (integer.intValue() == aLong.longValue()) 08: System.out.println("=="); 09: } 10: }

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What will be the result of compilation and execution of the following code: class User { private int id = 0; private String name; private String surname; public User () {} public User (int id, String name, String surname) { this.id = id; this.name = name; this.surname = surname; } Override public boolean equals (Object obj) { if (this == obj) return true; if (obj == null ||! getClass (). equals (obj.getClass ())) return false; User u = (User) obj; return id == u.id & Amp; & amp; name == u.name || (name! = null & amp; & amp; name.equals (u.name)) & Amp; & amp; surname == u.surname || (surname! = null & amp; & amp; surname.equals (u.surname)); } Override public int hashCode () { return id + name == null? 0: name.hashCode () + surname == null? 0: surname.hashCode (); } public static void main (String args []) { User u1 = new User (12, "name", null); User u2 = new User (12, null, "name"); System.out.println (u1.hashCode () == u2.hashCode ()); System.out.println (u1.equals (u2)); } } </ Code> </ pre>

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What is the result of compilation and execution of the following code? enum Fish { GOLDFISH, ANGELFISH, GUPPY; } public class EnumTest2{ public static void main(String[] args){ Fish f = Fish.valueOf("GUPPY"); if (f == Fish.GUPPY) System.out.println("Are equal"); if (f.equals(Fish.GUPPY)) System.out.println("Are equal"); } }