return super.hashCode();
return name.hashCode() + age * 7;
return name.hashCode() + comment.hashCode() /2;
return name.hashCode() + comment.hashCode() / 2 - age * 3;
第1题:
阅读下面代码 abstract class Person { public Person(String n) { name=n; } public______String getDescription(); public String getName() { return name; } private String name; } 在下画线处应填入的修饰符是
A.static
B.abstract
C.protected
D.final
第2题:
给出下面不完整的类代码,则横线处的语句应该为( )。 class Person { String name,department; int age; public Person (Strings) {name=s;} public Person (String s,int
A.{name=s;age=a;} public Person (String n,String d,intA){ __________ department=d; } }A)Person (n,A);
B.this (Person(n,A));
C.this(n,A);
D.this(name,age);
第3题:
为使下列代码正常运行,应该在下画线处填入的选项是( )。 abstract class person{ public Person(String n){ name=n: } Public String getDescription; public String getName{ return name; } private string name; }
A.static
B.private
C.abstract
D.final
第4题:
public class Person { private String name, comment; private int age; public Person(String n, int a, String c) { name = n; age = a; comment = c; } public boolean equals(Object o) { if(! (o instanceof Person)) return false; Person p = (Person)o; return age == p.age && name.equals(p.name); } } What is the appropriate definition of the hashCode method in class Person?()
第5题:
public class Employee{ private String name; public Employee(String name){ this.name = name; } public String getName(){ return name; } } public class Manager extends Employee{ public Manager(String name){ System.out.println(getName()); } } 执行语句new Manager(“smith”)后程序的输出是哪项?()
第6题:
public class Plant { private String name; public Plant(String name) { this.name = name; } public String getName() { return name; } } public class Tree extends Plant { public void growFruit() { } public void dropLeaves() { } } Which is true?()
第7题:
smith,SALES
null,SALES
smith,null
null,null
编译错误
第8题:
smith
null
SALES
编译错误
第9题:
The equals method does NOT properly override the Object.equals method.
Compilation fails because the private attribute p.name cannot be accessed in line 5.
To work correctly with hash-based data structures, this class must also implement the hashCode method.
When adding Person objects to a java.util.Set collection, the equals method in line 4 will prevent duplicates.
第10题:
smith
null
编译错误
name
第11题:
The code will compile without changes.
The code will compile if public Tree() { Plant(); } is added to the Tree class.
The code will compile if public Plant() { Tree(); } is added to the Plant class.
The code will compile if public Plant() { this(”fern”); } is added to the Plant class.
The code will compile if public Plant() { Plant(”fern”); } is added to the Plant class.
第12题:
smith,SALES
null,SALES
smith,null
null,null
第13题:
给出下列的不完整的类代码,则下列的( )语句可以加到横线处。 class Person{ String name,department; int age public Person(String n){name=n;} public Person(String n,int a){name=n;age=a;} pubilc Person(String n,String d,int a) { _______________ department=d; } }
A.Person(n,a);
B.this(Person(n,a));
C.this(n,a);
D.this(name,age);
第14题:
Java代码查错
1.
abstract class Name {
private String name;
public abstract boolean isStupidName(String name) {}
}
大侠们,这有何错误?
错。abstract method 必须以分号结尾,且不带花括号。
第15题:
给出下列的不完整的类代码,则下列的哪个语句可以加到横线处? class Person { String name,department; int age; public Person( String n ){ name = n;} public Person( String n,int a ) { name = n;age = a;} public Person( String n,String d,int a ) { _____________ department = d; } }
A.Person(n,a);
B.this(Person(n,a) );
C.this(n,a);
D.this(name,age);
第16题:
public class Person { private name; public Person(String name) { this.name = name; } public int hashCode() { return 420; } } Which is true?()
第17题:
public class Employee{ private String name; public Employee(String name){ this.name = name; } public void display(){ System.out.print(name); } } public class Manager extends Employee{ private String department; public Manager(String name,String department){ super(name); this.department = department; } public void display(){ System.out.println( super.display()+”,”+department); } } 执行语句new Manager(“smith”,”SALES”)后程序的输出是哪项?()
第18题:
public class Person { private name; public Person(String name) { this.name = name; } public boolean equals(Object o) { if( !o instanceof Person ) return false; Person p = (Person) o; return p.name.equals(this.name); } } Which is true?()
第19题:
Compilation fails because the hashCode method is not overridden.
A HashSet could contain multiple Person objects with the same name.
All Person objects will have the same hash code because the hashCode method is not overridden.
If a HashSet contains more than one Person object with name=”Fred”, then removing another person, also with name=”Fred”, will remove them all.
第20题:
The time to find the value from HashMap with a Person key depends on the size of the map.
Deleting a Person key from a HashMap will delete all map entries for all keys of typePerson.
Inserting a second Person object into a HashSet will cause the first Person object to beremoved as a duplicate.
The time to determine whether a Person object is contained in a HashSet is constant and does NOT depend on the size of the map.
第21题:
return super.hashCode();
return name.hashCode() + age * 7;
return name.hashCode() + comment.hashCode() /2;
return name.hashCode() + comment.hashCode() / 2 - age * 3;
第22题:
declare reset() using the synchronized keyword
declare getName() using the synchronized keyword
declare getCount() using the synchronized keyword
declare the constructor using the synchronized keyword
declare increment() using the synchronized keyword
第23题:
Person(n,a);
this(Person(n,a));
this(n,a);
this(name,age);
第24题:
smith
null
SALES
编译错误