「java类和对象课后习题」java类与对象例题
本篇文章给大家谈谈java类和对象课后习题，以及java类与对象例题对应的知识点，希望对各位有所帮助，不要忘了收藏本站喔。
本文目录一览：
- 1、用JAVA编程 类与对象的基础题
- 2、关于java中的类和对象等，急!要交作业!
- 3、（Java类和对象练习）.
- 4、关于Java类与对象练习，初学求多多指教~分数不多哦，多谢了~
- 5、谁能提供JAVA 类和对象的练习题!!
- 6、java基础有关面向对象，类的，2题
用JAVA编程 类与对象的基础题
class Phone{
private String phonenumber;
public void setPhonenumber(String phonenumber){
this.phonenumber=phonenumber;
}
public String getPhonenumber(){
return phonenumber;
}
public void recCall(){
System.out.println("接到一个电话");
}
public void telCall(){
System.out.println("拨出一个电话");
}
}class Fixedphone extends Phone{
private String phonenumber;//号码是私有，设置为private，不可继承
public void recCall(){
System.out.println("以"+this.phonenumber+"呼出了一个电话"); //重载了父类的recCall
}
}class Cordlessphone extends Fixedphone{
private String phonenumber;
public void info(){
System.out.println("这是无绳电话的信息");
}
}interface Moveable{
public void moveinfo();
}class Mobilephone extends Phone implements Moveable{
private String phonenumber;
public void moveinfo(){
System.out.println("我实现了可移动性");
}
}public class PhoneTest{
public static void main(String a[]){
Phone[] p=new Phone[5];
Phone p1=new Phone();
p1.setPhonenumber("123456789");
p[0]=p1;
Phone p2=new Phone();
p2.setPhonenumber("987654321");
p[1]=p2;
Mobilephone mp=new Mobilephone();
mp.setPhonenumber("11111");
p[2]=mp;
Fixedphone fp=new Fixedphone();
fp.setPhonenumber("22222");
p[3]=fp;
Cordlessphone cp=new Cordlessphone();
cp.setPhonenumber("33333");
p[4]=cp;
for(int i=0;ip.length;i++){
System.out.println(p[i].getPhonenumber());
} p[4]=p[1];
System.out.println(p[4].getPhonenumber());
}} 写的不是很好，希望对你有帮助噶
关于java中的类和对象等，急!要交作业!
public class StudentTest {
public static void main(String[] args) {
Student s1=new Student("张三",18,201701);
System.out.println(s1);
s1.meal();
Student s2=new Student("李四",19,201702);
System.out.println(s2);
s2.meal();
Student s3=new Student("王五",17,201703);
System.out.println(s3);
s3.meal();
}
}
//学生类!
class Student {
private String name;// 姓名
private int age;// 年龄!
private int cla;// 班级!
Student(String name, int age, int cla) {
this.name = name;
this.age = age;
this.cla = cla;
}// 属性查询!
public String toString() {
return "姓名:"+name + "\t年龄:" + age + "\t学号:" + cla;
}
public void meal() {
System.out.println(name+"在吃饭!");
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public int getCla() {
return cla;
}
public void setCla(int cla) {
this.cla = cla;
}
}
（Java类和对象练习）.
import java.util.Arrays;
import java.util.Comparator;
class Student
{
public String stuNo;
public String stuName;
public int stuAge;
public Student(String stuNo,String stuName,int stuAge)
{
this.stuNo = stuNo;
this.stuName = stuName;
this.stuAge = stuAge;
}
public void addAge()
{
stuAge++;
}
public String toString()
{
return "No:" + stuNo + " Name:" + stuName + " Age:" + stuAge;
}
}
class StudentOrder implements ComparatorStudent
{
@Override
public int compare(Student o1, Student o2)
{
// TODO Auto-generated method stub
return o1.stuNo.compareTo(o2.stuNo);
}
}
public class Test3
{
public static void main(String[] args)
{
Student[] students = new Student[5];
students[0] = new Student("1003", "a", 12);
students[1] = new Student("1002", "b", 13);
students[2] = new Student("1004", "c", 14);
students[3] = new Student("1001", "d", 15);
students[4] = new Student("1005", "e", 16);
Arrays.sort(students, new StudentOrder());
int count = 0;
for(int i = 0 ; i 5 ; i++)
{
System.out.println(students[i]);
students[i].addAge();
if(students[i].stuAge 20)
count++;
}
System.out.println("大于20岁的人数:" + count);
}
}
关于Java类与对象练习，初学求多多指教~分数不多哦，多谢了~
1. 程序中仅仅省略【代码12】编译能通过吗？
答:编译可以通过，但运行时异常
2. 程序中仅仅省略【代码13】编译能通过吗？
答:编译无法通过
3. 程序中仅仅省略【代码12】，运行时出现了怎样的异常提示？
答:java.lang.NullPointerException
4. 给Trangle类增加3个方法，分别用来返回3个边：sideA、sideB和sideC。
答:
public double getSideA() {
return sideA;
}
public double getSideB() {
return sideB;
}
public double getSideC() {
return sideC;
}
三个类的完整代码:
class Trangle {
double sideA, sideB, sideC, area, length;
boolean boo;
public Trangle(double a, double b, double c) {
this.sideA = a;
this.sideB = b;
this.sideC = c;
if (a + b c a + c b b + c a) {
boo = true;
} else {
boo = false;
}
}
public double getSideA() {
return sideA;
}
public double getSideB() {
return sideB;
}
public double getSideC() {
return sideC;
}
double getLength() {
return this.sideA + this.sideB + this.sideC;
}
public double getArea() {
if (boo) {
double p = (sideA + sideB + sideC) / 2.0;
area = Math.sqrt(p * (p - sideA) * (p - sideB) * (p - sideC));
return area;
} else {
System.out.println("不是一个三角形,不能计算面积");
return 0;
}
}
public void setABC(double a, double b, double c) {
this.sideA = a;
this.sideB = b;
this.sideC = c;
if (a + b c a + c b b + c a) {
boo = true;
} else {
boo = false;
}
}
}
class Lader {
double above, bottom, height, area;
Lader(double a, double b, double h) {
this.above = a;
this.bottom = b;
this.height = h;
}
double getArea() {
return (this.above + this.bottom) * this.height / 2;
}
}
class AreaAndLength {
public static void main(String args[]) {
double length, area;
Trangle trangle = null;
Lader lader;
// 创建对象trangle。
trangle = new Trangle(3, 4, 5);// 12
// 创建对象lader。
lader = new Lader(3, 4, 5);// 13
// trangle调用方法返回周长并赋值给length。
length = trangle.getLength();// 14
System.out.println("三角形的周长:" + length);
// trangle调用方法返回面积并赋值给area。
area = trangle.getArea();// 15
System.out.println("三角形的面积:" + area);
// lader调用方法返回面积并赋值给area。
area = lader.getArea();// 16
System.out.println("梯形的面积:" + area);
// trangle调用方法返修改三个边的代码，要求将三个边修改为12,34,1。
trangle.setABC(12, 34, 1);// 17
// trangle调用方法返回面积并赋值给area。
area = trangle.getArea();// 18
System.out.println("三角形的面积:" + area);
// trangle调用方法返回周长并赋值给length。
length = trangle.getLength();// 19
System.out.println("三角形的周长:" + length);
}
}
谁能提供JAVA 类和对象的练习题!!
Question No: 1
public class test (
2. public static void main (String args[]) {
3. int i = 0xFFFFFFF1;
4. int j = ~i;
5.
6. }
7. )
What is the decimal value of j at line 5?
A. 0
B. 1
C. 14
D. –15
E. An error at line 3 causes compilation to fail.
F. An error at line 4 causes compilation to fail.
答案: C
Question No: 2
Given:
Integer i = new Integer (42);
Long 1 = new Long (42);
Double d = new Double (42.0);
Which two expressions evaluate to True? (Choose Two)
A. (i ==1)
B. (i == d)
C. (d == 1)
D. (i.equals (d))
E. (d.equals (i))
F. (i.equals (42))
答案: D, E
Question No: 3
Exhibit :
1. public class test (
2. private static int j = 0;
3.
4. private static boolean methodB(int k) (
5. j += k;
6. return true;
6. )
7.
8. public static void methodA(int i) {
9. boolean b:
10. b = i 10 | methodB (4);
11. b = i 10 || methodB (8);
12. }
13.
14. public static void main (String args[] ) (
15. methodA (0);
16. system.out.printIn(j);
17. )
18. )
What is the result?
A. The program prints “0”
B. The program prints “4”
C. The program prints “8”
D. The program prints “12”
E. The code does not complete.
答案: B
Question No: 4
Given
1. Public class test (
2. Public static void main (String args[]) (
3. System.out.printIn (6 ^ 3);
4. )
5. )
What is the output?
答案: 5
Question No: 5
Given:
1. public class Foo {
2. public static void main (String [] args) {
3. StringBuffer a = new StringBuffer (“A”);
4. StringBuffer b = new StringBuffer (“B”);
5. operate (a,b);
6. system.out.printIn{a + “,” +b};
7. }
8. static void operate (StringBuffer x, StringBuffer y) {
9. x.append {y};
10. y = x;
11. }
12. }
What is the result?
A. The code compiles and prints “A,B”.
B. The code compiles and prints “A,A”.
C. The code compiles and prints “B,B”.
D. The code compiles and prints “AB,B”.
E. The code compiles and prints “AB,AB”.
F. The code does not compile because “+” cannot be overloaded for StringBuffer.
答案: D
Question No: 6
Exhibit:
1. Public class test (
2. Public static void stringReplace (String text) (
3. Text = text.replace (‘j’ , ‘i’);
4. )
5.
6. public static void bufferReplace (StringBuffer text) (
7. text = text.append (“C”)
8. )
9.
10. public static void main (String args[]) (
11. String textString = new String (“java”);
12. StringBuffer text BufferString = new StringBuffer (“java”);
13.
14. stringReplace (textString);
15. BufferReplace (textBuffer);
16.
17. System.out.printIn (textString + textBuffer);
18. )
19. )
What is the output?
答案: JAVAJAVA
Question No: 7
Exhibit:
1. public class test {
2. public static void add3 (Integer i) }
3. int val = i.intValue ( );
4. val += 3;
5. i = new Integer (val);
6. )
7.
8. public static void main (String args [ ] ) {
9. Integer i = new Integer (0);
10. add3 (i);
11. system.out.printIn (i.intValue ( ) );
12. }
13. )
What is the result?
A. Compilation will fail.
B. The program prints “0”.
C. The program prints “3”.
D. Compilation will succeed but an exception will be thrown at line 3.
答案: B
Question No: 8
Given:
1. public class ConstOver {
2. public ConstOver (int x, int y, int z) {
3. }
4. }
Which two overload the ConstOver constructor? (Choose Two)
A. ConstOver ( ) { }
B. Protected int ConstOver ( ) { }
C. Private ConstOver (int z, int y, byte x) { }
D. Public Object ConstOver (int x, int y, int z) { }
E. Public void ConstOver (byte x, byte y, byte z) { }
答案: A, C
Question No: 9
Given:
1. public class MethodOver {
2. public void setVar (int a, int b, float c) {
3. }
4. }
Which two overload the setVar method? (Choose Two)
A. Private void setVar (int a, float c, int b) { }
B. Protected void setVar (int a, int b, float c) { }
C. Public int setVar (int a, float c, int b) (return a;)
D. Public int setVar (int a, int b, float c) (return a;)
E. Protected float setVar (int a, int b, float c) (return c;)
答案: A, C
Question No: 10
Given:
1. class BaseClass {
2. Private float x = 1.0f ;
3. protected float getVar ( ) ( return x;)
4. }
5. class Subclass extends BaseClass (
6. private float x = 2.0f;
7. //insert code here
8. )
Which two are valid examples of method overriding? (Choose Two)
A. Float getVar ( ) { return x;}
B. Public float getVar ( ) { return x;}
C. Float double getVar ( ) { return x;}
D. Public float getVar ( ) { return x;}
E. Public float getVar (float f ) { return f;}
答案: B, D
Question No: 11
Which two demonstrate an “is a” relationship? (Choose Two)
A. public interface Person { }
public class Employee extends Person { }
B. public interface Shape { }
public class Employee extends Shape { }
C. public interface Color { }
public class Employee extends Color { }
D. public class Species { }
public class Animal (private Species species;)
E. interface Component { }
Class Container implements Component (
Private Component[ ] children;
)
答案: D, E
Question No: 12
Which statement is true?
A. An anonymous inner class may be declared as final.
B. An anonymous inner class can be declared as private.
C. An anonymous inner class can implement multiple interfaces.
D. An anonymous inner class can access final variables in any enclosing scope.
E. Construction of an instance of a static inner class requires an instance of the enclosing outer class.
答案: D
Question No 13
Given:
1. package foo;
2.
3. public class Outer (
4. public static class Inner (
5. )
6. )
Which statement is true?
A. An instance of the Inner class can be constructed with “new Outer.Inner ()”
B. An instance of the inner class cannot be constructed outside of package foo.
C. An instance of the inner class can only be constructed from within the outer class.
D. From within the package bar, an instance of the inner class can be constructed with “new inner()”
答案: A
Question No 14
Exhibit:
1. public class enclosingone (
2. public class insideone{}
3. )
4. public class inertest(
5. public static void main (string[]args)(
6. enclosingone eo= new enclosingone ();
7. //insert code here
8. )
9. )
Which statement at line 7 constructs an instance of the inner class?
A. InsideOnew ei= eo.new InsideOn();
B. Eo.InsideOne ei = eo.new InsideOne();
C. InsideOne ei = EnclosingOne.new InsideOne();
D. EnclosingOne.InsideOne ei = eo.new InsideOne();
答案: D
Question No 15
Exhibit:
1. interface foo {
2. int k = 0;
3. }
4.
5. public class test implements Foo (
6. public static void main(String args[]) (
7. int i;
8. Test test = new test ();
9. i= test.k;
10.i= Test.k;
11.i= Foo.k;
12.)
13.)
14.
What is the result?
A. Compilation succeeds.
B. An error at line 2 causes compilation to fail.
C. An error at line 9 causes compilation to fail.
D. An error at line 10 causes compilation to fail.
E. An error at line 11 causes compilation to fail.
答案: A
Question No 16
Given:
1. //point X
2. public class foo (
3. public static void main (String[]args) throws Exception {
4. printWriter out = new PrintWriter (new
5. java.io.outputStreamWriter (System.out), true;
6. out.printIn(“Hello”);
7. )
8. }
Which statement at PointX on line 1 allows this code to compile and run?
A. Import java.io.PrintWriter;
B. Include java.io.PrintWriter;
C. Import java.io.OutputStreamWriter;
D. Include java.io.OutputStreamWriter;
E. No statement is needed.
答案: A
Question No 17
Which two statements are reserved words in Java? (Choose Two)
A. Run
B. Import
C. Default
D. Implement
答案: B, C
Question No 18
Which three are valid declarations of a float? (Choose Three)
A. Float foo = -1;
B. Float foo = 1.0;
C. Float foo = 42e1;
D. Float foo = 2.02f;
E. Float foo = 3.03d;
F. Float foo = 0x0123;
答案: A, D, F
Question No 19
Leading the way in IT testing and certification tools,
Question No 19
Given:
8. int index = 1;
9. boolean[] test = new Boolean[3];
10. boolean foo= test [index];
What is the result?
A. Foo has the value of 0.
B. Foo has the value of null.
C. Foo has the value of true.
D. Foo has the value of false.
E. An exception is thrown.
F. The code will not compile.
答案: D
Question No 20
Given:
1. public class test(
2. public static void main(string[]args){
3. string foo = args [1];
4. string foo = args [2];
5. string foo = args [3];
6. }
7. )
And command line invocation:
Java Test red green blue
What is the result?
A. Baz has the value of “”
B. Baz has the value of null
C. Baz has the value of “red”
D. Baz has the value of “blue”
E. Bax has the value of “green”
F. The code does not compile.
G. The program throws an exception.
答案: G
Question No 21
Given:
8. int index = 1;
9. int [] foo = new int [3];
10.int bar = foo [index];
11.int baz = bar + index;
What is the result?
A. Baz has the value of 0
B. Baz has the value of 1
C. Baz has the value of 2
D. An exception is thrown.
E. The code will not compile.
答案: B
Question No 22
Given:
1. public class foo {
2. public static void main (String[]args) {
3. String s;
4. system.out.printIn (“s=” + s);
5. }
6. }
What is the result?
A. The code compiles and “s=” is printed.
B. The code compiles and “s=null” is printed.
C. The code does not compile because string s is not initialized.
D. The code does not compile because string s cannot be referenced.
E. The code compiles, but a NullPointerException is thrown when toString is called.
答案: C
Question No 23
Which will declare a method that forces a subclass to implement it?
A. Public double methoda();
B. Static void methoda (double d1) {}
C. Public native double methoda();
D. Abstract public void methoda();
E. Protected void methoda (double d1){}
答案: D
Question No 24
You want subclasses in any package to have access to members of a superclass. Which is the most
restrictive access modifier that will accomplish this objective?
A. Public
B. Private
C. Protected
D. Transient
E. No access modifier is qualified
答案: C
Question No 25
Given:
1. abstract class abstrctIt {
2. abstract float getFloat ();
3. }
4. public class AbstractTest extends AbstractIt {
5. private float f1= 1.0f;
6. private float getFloat () {return f1;}
7. }
What is the result?
A. Compilation is successful.
B. An error on line 6 causes a runtime failure.
C. An error at line 6 causes compilation to fail.
D. An error at line 2 causes compilation to fail.
答案: C
Question No 26
Exhibit:
1. public class test(
2. public int aMethod()[
3. static int i=0;
4. i++;
5. return I;
6. ]
7. public static void main (String args[]){
8. test test = new test();
9. test.aMethod();
10.int j = test.aMethod();
11.System.out.printIn(j);
12.}
13.)
What is the result?
A. Compilation will fail.
B. Compilation will succeed and the program will print “0”
C. Compilation will succeed and the program will print “1”
D. Compilation will succeed and the program will print “2”
答案: D
Question No 27
Given:
1. class super {
2. public float getNum() {return 3.0f;}
3. }
4.
5. public class Sub extends Super {
6.
7. }
Which method, placed at line 6, will cause a compiler error?
A. Public float getNum() {return 4.0f; }
B. Public void getNum () { }
C. Public void getNum (double d) { }
D. Public double getNum (float d) {retrun 4.0f; }
答案: B
Question No 28
Which declaration prevents creating a subclass of an outer class?
A. Static class FooBar{}
B. Private class FooBar{}
C. Abstract public class FooBar{}
D. Final public class FooBar{}
E. Final abstract class FooBar{}
答案: D
Question No 29
Given:
1. byte [] arry1, array2[];
2. byte array3 [][];
3. byte[][] array4;
If each array has been initialized, which statement will cause a compiler error?
A. Array2 = array1;
B. Array2 = array3;
C. Array2 = array4;
D. Both A and B
E. Both A and C
F. Both B and C
答案: F
Question No 30
Exhibit:
1. class super (
2. public int I = 0;
3.
4. public super (string text) (
5. I = 1
6. )
7. )
8.
9. public class sub extends super (
10. public sub (string text) (
11. i= 2
12. )
13.
14. public static void main (straing args[]) (
15. sub sub = new sub (“Hello”);
16. system.out. PrintIn(sub.i);
17. )
18. )
What is the result?
A. Compilation will fail.
B. Compilation will succeed and the program will print “0”
C. Compilation will succeed and the program will print “1”
D. Compilation will succeed and the program will print “2”
答案: A
Question No 31
Given:
1. public class returnIt (
2. returnType methodA(byte x, double y) (
3. return (short) x/y * 2;
4. )
5. )
What is the valid returnType for methodA in line 2?
A. Int
B. Byte
C. Long
D. Short
E. Float
F. Double
答案: F
Question No 32
Given the ActionEvent, which method allows you to identify the affected component?
A. GetClass.
B. GetTarget.
C. GetSource.
D. GetComponent.
E. GetTargetComponent.
答案: C
Question No 33
Which is a method of the MouseMotionListener interface?
A. Public void mouseMoved(MouseEvent)
B. Public boolean mouseMoved(MouseEvent)
C. Public void mouseMoved(MouseMotionEvent)
D. Public boolean MouseMoved(MouseMotionEvent)
E. Public boolean mouseMoved(MouseMotionEvent)
答案: A
java基础有关面向对象，类的，2题
1.
public class School{
private double scoreLine; // 录取分数线
public School() {
}
public School(double scoreLine) {
this.scoreLine = scoreLine;
}
public double getScoreLine() {
return scoreLine;
}
public void setScoreLine(double scoreLine) {
this.scoreLine = scoreLine;
}
}
2.
/**
* 学生类
*/
public class Student {
private int id; // 考号
private String name; // 考生姓名
private double score; // 综合成绩
private double sports; // 体育成绩
/**
* 无参构造方法
*/
public Student() {
}
/**
*
* 构造方法说明：有参构造方法br/
* br/
*
* @param id 考号
* @param name 考生姓名
* @param score 综合成绩
* @param sports 体育成绩
*/
public Student(int id,String name, double score, double sports){
this.id = id;
this.name = name;
this.score = score;
this.sports = sports;
}
/**
*
* 方法说明：获取综合成绩br/
* br/
*
* @return 综合成绩
*/
public double getScore() {
return score;
}
/**
*
* 方法说明：获取体育成绩br/
* br/
*
* @return 体育成绩
*/
public double getSports() {
return sports;
}
}
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发布于：2022-11-23，除非注明，否则均为原创文章，转载请注明出处。