无答案版链接:https://blog.csdn.net/a2272062968/article/details/117787974
public class MyFor{
public static void main(String argv[]){
int i, j;
outer: for (i=1;i <3;i++)
inner: for (j=1; j<3; j++) {
if (j==2)continue outer;
System.out.println("Value for i=" + i + " Value for j=" +j);
}
}
}
1.1 1.2
答案:
1.1: Value for i=1 Value for j=1
1.2: Value for i=2 Value for j=1
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int number, max;
number = input.nextInt();
max = number;
while (number != 0) {
number = input.nextInt();
if (number > max)
max = number;
}
System.out.println("max is " + max);
System.out.println("number " + number);
}
}
假设输入是 2 3 4 5 0,程序输出是:
max is 2.1
number 2.2
答案:
2.1: 5
2.2: 0
Loop1:
while ( true ) { // 1
for ( ; true; ) {
if ( i ==2 )
break Loop1; // 2
}
i=4; // 3
}
i=5; // 4
After executing line 2, where will the program jump to? 3.1
答案:
3.1: 4
package Testpackage;
public class Class1{
… …
}
The main() is in MainPro.java as below:
import Testpackage.*;
… …
The CLASSPATH is "c:\java\lib\classes.zip;.; ". The MainPro.java is in c:\Testdir. The current directory is c:\Testdir. Where should we put the Class1.class? 4.1
答案:
4.1: c:\Testdir\Testpackage
public class Test extends TT{
public static void main(String args[]){
Test t=new Test("Tom");
}
public Test(String s){
super(s);
System.out.println("How do you do?");
}
public Test(){
this("I am Tom");
}
}
class TT {
public TT(){
System.out.println("What a pleasure!");
}
public TT(String s){
this();
System.out.println("I am "+s);
}
}
程序运行结果为: 5.1 5.2 5.3
答案:
5.1: What a pleasure!
5.2: I am Tom
5.3: How do you do?
在Java程序中,创建一个包即打包操作,应使用关键词 6.1
,该关键词引导的语句必须放在程序的第 6.2
行,该行前只能有空格及注释。
在Java程序中,想要导入不同包下面的某个类时,可以使用关键词 6.3
答案:
6.1: package
6.2: 一
6.3: import
阅读下列程序:
1. public class Main{
public static void main(String[]args){
System.out.println("创建一个Faculty对象");
new Faculty();
}
}
class Faculty extends Employee {
public Faculty(){
System.out.println("完成Faculty的任务");
}
}
class Employee extends Person{
public Employee(){
this("调用Employee的重载构造方法");
System.out.println("完成Employee的任务");
}
public Employee(String s){
System.out.println(s);
}
}
class Person {
public Person() {
System.out.println("完成Person的任务");
}
}
从下面选项中进行选择,将相应序号(1、2、3、4、5中选其一)填入空格中:
(1)完成Person的任务
(2)完成Employee的任务
(3)完成Faculty的任务
(4)调用Employee的重载构造方法
(5)创建一个Faculty对象
按程序执行顺序输出结果: 7.1 7.2 7.3 7.4 7.5
答案:
7.1: 5
7.2: 1
7.3: 4
7.4: 2
7.5: 3
class Number {
int i;
public Number(int ii) { i=ii; }
}
public class Main {
public static void main(String[] args) {
Number[] a = new Number[5];
for ( int i=0; i<a.length; i++ ) a[i] = new Number(i);
for ( int i=0; i<2; i++ )
for ( Number n : a ) {
System.out.print(n.i);
n.i = 5-n.i;
}
}
}
程序运行结果是: 8.1
答案:
8.1: 0123454321
Java的三大体系分别是封装、( )、( )。 9.1 9.2
答案:
9.1: 继承
9.2: 多态
给出以下代码:
public class Test {
public int t=4;
public static void main(String[] args) {
new Test().NumberPlay();
}
public void NumberPlay() {
int t=2;
t = t+5;
this.t = this.t-2;
t = t-this.t;
System.out.println(t+this.t+"ok");
}
}
程序运行后输出结果为: 10.1
答案:
10.1: 7ok
定义在类中的变量被称为( ),定义在方法中的变量被称为( )。 11.1 11.2
答案:
11.1: 成员变量
11.2: 局部变量
访问父类的成员可以使用 12.1 关键字。
答案:
12.1: super
说出下列A类中【代码1】~【代码3】的输出结果
class Fish { int weight=1; }
class Lake{
Fish fish;
void setFish(Fish s) { fish=s; }
void foodFish(int m){ fish.weight=fish.weight+m; }
}
public class Main {
public static void main(String args[]){
Fish redFish=new Fish();
System.out.println(redFish.weight);//【代码1】
Lake lake=new Lake();
lake.setFish(redFish);
lake.foodFish(120);
System.out.println(redFish.weight);//【代码2】
System.out.println(lake.fish.weight);//【代码3】
}
}
【代码1】 13.1
【代码2】 13.2
【代码3】 13.3
答案:
13.1: 1
13.2: 121
13.3: 121
阅读以下程序,写出输出结果。
public class AppleMobilePhone extends MobilePhone{
public static void main(String[] args){
new AppleMobilePhone();
}
public AppleMobilePhone(){
System.out.println("This is a Applemobilephone");
}
}
class MobilePhone extends Phone{
public MobilePhone(){
System.out.println("This is a mobilephone");
}
}
class Phone{
public Phone(){
System.out.println("This is a phone");
}
}
程序运行后输出: 从下列选项中选,在空格处填上相应的序号数字(1、2或3)
(1)This is a phone
(2)This is a Apple mobile phone
(3)This is a mobile phone
第一行输出: 14.1
第二行输出: 14.2
第三行输出: 14.3
答案:
14.1: 1
14.2: 3
14.3: 2
请说出A类中System.out.println的输出结果。
class B{
int x=100,y=200;
public void setX(int x){ x=x; }
public void setY(int y){ this.y=y; }
public int getXYSum(){ return x+y; }
}
public class A {
public static void main(String args[]){
B b=newB();
b.setX(-100);
b.setY(-200);
System.out.println("sum="+b.getXYSum());
}
}
程序输出结果为:sum= 15.1
答案:
15.1: -100
已知代码:
class A{
String name="A";
String getName(){
return name;
}
String greeting(){
return "class A";
}
}
class B extends A{
String name="B";
String greeting(){
return "class B";
}
}
public class Main{
public static void main(String args[]){
A a=new A();
A b=new B();
System.out.println(a.greeting()+" has name "+a.getName());
System.out.println(b.greeting()+" has name "+b.getName());
}
}
在下列运行结果的空格中选择填写A或B:
class 16.1
has name 16.2
class 16.3
has name 16.4
答案:
16.1: A
16.2: A
16.3: B
16.4: A
阅读下列程序:
class Animal{
Animal(){ System.out.println("我是动物"); }
void shout(){ System.out.println("动物叫"); }
}
class Dog extends Animal{
void shout(){
super.shout();
System.out.println("汪汪");
}
}
class Cat extends Animal{
void shout(){ System.out.println("喵喵"; }
}
public class Test{
public static void main(String[]args){
Animal dog=newDog();
Animal cat=newCat();
dog.shout();
cat.shout();
}
}
按程序执行顺序输出结果:
(1) 17.1
(2) 17.2
(3) 17.3
(4) 17.4
(5) 17.5
答案:
17.1: 我是动物
17.2: 我是动物
17.3: 动物叫
17.4: 汪汪
17.5: 喵喵
阅读以下程序,在空格内填上正确答案。
public class Test {
public static void main(String[] args) {
int number = 0;
int[] numbers = new int[1];
m(number, numbers);
System.out.println("number is " + number+ " and numbers[0] is " + numbers[0]);
}
public static void m(int x, int[] y) {
x = 3;
y[0] = 3;
}
}
程序运行后,输出:
number is 18.1
and numbers[0] is 18.2
答案:
18.1: 0
18.2: 3
阅读下列程序:
class A{
int i=7;
public A(){
setI(20);
System.out.println("i="+i);
}
public void setI(int i){
this.i=2*i;
}
}
class B extends A{
public B(){
System.out.println("i="+i);
}
public void setI(int i){
this.i=3*i;
}
}
public class Main{
public static void main(String[] args){
new A();
new B();
}
}
程序运行后依次输出: 19.1 19.2 19.3
答案:
19.1: i=40
19.2: i=60
19.3: i=60
请写出以下程序运行结果:
class A
{
int x;
String s;
};
class HelloWorld
{
public static void main(String[] args)
{
A a= new A();
System.out.println(a.s);
System.out.println(a.x);
}}
20.1 20.2
答案:
20.1: null
20.2: 0
请写出以下程序运行结果:
class Window {
Window(int marker) { System.out.println("Window(" + marker + ")"); }
}
class House {
Window w1 = new Window(1);
House() {
System.out.println("House()");
w3 = new Window(33);
}
Window w2 = new Window(2);
void f() {
System.out.println("f()");
}
static Window w3 = new Window(3);
}
public class Est {
public static void main(String[] args) {
House h = new House();
h.f();
}
}
21.1 21.2 21.3 21.4 21.5 21.6
答案:
21.1: Window(3)
21.2: Window(1)
21.3: Window(2)
21.4: House()
21.5: Window(33)
21.6: f()
接口中的方法的默认的访问权限是 22.1 。
答案:
22.1: public
已知代码:
class MyDate{
int year;
int month;
int day;
MyDate(int year,int month,int day){
this.year=year;
this.month=month;
this.day=day;
}
}
public class Main{
public static void main(String args[]){
MyDate md1=new MyDate(2009,2,10);
MyDate md2=new MyDate(2009,2,10);
if(md1==md2)
System.out.println("md1==md2");
else
System.out.println("md1!=md2");
if(md1.equals(md2))
System.out.println("md1 is equla to md2");
else
System.out.println("md1 is not equal to md2");
}
}
运行上述代码,写出其运行结果: 23.1 23.2
答案:
23.1: md1!=md2
23.2: md1 is not equal to md2
用 24.1 关键字修饰的类不能被继承。
答案:
24.1: final
请写出以下程序运行结果:
class Letter {
char c;
}
public class Main {
static void f(Letter y) {
y.c = 'z';
}
public static void main(String[] args) {
Letter x = new Letter();
x.c = 'a';
f(x);
System.out.println(x.c);
}
}
25.1
答案:
25.1: z
运行下列代码,运行结果是什么?
public class Main{
int i=2;
static int is;
static{
System.out.println("in static block");
is=5;
System.out.println("static variable is="+is);
}
{
System.out.println("in non-static block");
i=8;
}
Main(){
i=10;
}
public static void main(String args[]){
System.out.println("in main()");
Main m1=new Main();
System.out.println(m1.i);
}
}
运行上述代码,则运行结果为: 26.1 26.2 26.3 26.4 26.5
答案:
26.1: in static block
26.2: static variable is=5
26.3: in main()
26.4: in non-static block
26.5: 10
一个类如果实现一个接口,那么它就需要实现接口中定义的全部( ),否则该类就必须定义成( )。 27.1 27.2
答案:
27.1: 方法
27.2: 抽象类
给出以下代码:
class Number {
public int i;
public Number(int ii) {i=ii;};
}
public class Main {
static void f(Number n) {
n.i = 9;
}
static void g(Integer n) {
n=9;
}
public static void main(String[] args) {
Number k = new Number(10);
f(k);
Integer m = new Integer(10);
g(m);
System.out.println(k.i+":"+m);
}
}
程序运行后输出结果是: 28.1
答案:
28.1: 9:10
下列代码的运行结果是什么?
public class Main{
static{
System.out.print("Hi here,");
}
public void print(){
System.out.print("Hello");
}
public static void main(String args[]){
Main m1=new Main();
m1.print();
Main m2=new Main();
m2.print();
}
}
上述代码的运行结果为: 29.1
答案:
29.1: Hi here,HelloHello
请写出以下程序运行结果:
class NoWater extends Exception {}
class NoDrinkableWater extends NoWater {}
public class FinallyWorks {
static int count = 0;
public static void main(String[] args) throws NoWater {
while ( true ) {
try {
count++;
if ( count == 1 ) {
System.out.println("OK");
} else if ( count == 2 ) {
System.out.println("Exception raised: NoDrinkableWater");
throw new NoDrinkableWater();
} else if ( count == 3 ) {
System.out.println("Exception raised: NoWater");
throw new NoWater();
}
} catch (NoDrinkableWater e) {
System.out.println(e);
} finally {
System.out.println("finally");
if ( count == 3 )
break;
}
}
}
}
30.1 30.2 30.3 30.4 30.5 30.6 30.7
答案:
30.1: OK
30.2: finally
30.3: Exception raised: NoDrinkableWater
30.4: NoDrinkableWater
30.5: finally
30.6: Exception raised: NoWater
30.7: finally
请写出以下程序运行结果:
public class X {
public static void main(String [] args) {
try {
badMethod();
System.out.print("A");
} catch (RuntimeException ex) {
System.out.print("B");
} catch (Exception ex1) {
System.out.print("C");
} finally {
System.out.print("D");
}
System.out.print("E");
}
public static void badMethod() {
throw new RuntimeException();
}}
31.1
答案:
31.1: BDE
请写出以下程序运行结果:
class Exception1 extends Exception {}
class Exception2 extends Exception1 {}
public class Test {
public static void main(String[] args)
throws Exception {
try {
try {
throw new Exception2();
} catch ( Exception1 a ) {
System.out.println("Caught Exception1");
throw a;
}
} catch ( Exception2 s ) {
System.out.println("Caught Exception2");
return ;
} finally {
System.out.println("Hello World!");
}}}
32.1 32.2 32.3
答案:
32.1: Caught Exception1
32.2: Caught Exception2
32.3: Hello World!
在Java中,用户自定义异常类必须继承 33.1
类, 用户人工抛出自定义异常使用关键词 33.2 。
答案:
33.1: Exception
33.2: throw
在Java中, 34.1 类是所有异常和错误的顶级父类。
答案:
34.1: Throwable
当编译并运行下列代码时,其运行结果是什么?
public class Main{
public static void main(String args[]){
String s="Hello";
methodA(s);
s=s.replace('e', 'a');
System.out.println(s);
}
public static void methodA(String str){
str+="World";
}
}
上述代码的运行结果为: 35.1
答案:
35.1: Hallo
当编译并运行下列代码时,其运行结果是什么?
public class Main{
public static void main(String args[]){
String s="Java";
StringBuffer sb=new StringBuffer("Java");
change(s);
change(sb);
System.out.println(s+sb);
}
public static void change(String s){
s=s.concat("Hello");
}
public static void change(StringBuffer sb){
sb.append("Hello");
}
}
上述代码的运行结果为: 36.1
答案:
36.1: JavaJavaHello
给出以下代码:
public class Main {
int i=0;
Main(int ii) { i = ii; }
Main(String s) { this(s.length()); }
public String toString() { return String.format("%02X",i); }
public static void main(String[] args) {
Main m = new Main("hello world");
System.out.println(m);
}
}
程序运行输出结果是: 37.1
答案:
37.1: 0B
当编译并运行下列代码时,其运行结果时什么?
public class Main{
public static void main(String args[]){
String s="Java";
StringBuffer sb=new StringBuffer("Java");
hello(sb,s);
System.out.println(sb+s);
}
public static void hello(StringBuffer sb, String s){
sb.append("A");
s=sb.toString();
}
}
上述代码的运行结果为: 38.1
答案:
38.1: JavaAJava
当编译并运行下列代码时,其运行结果是什么?
public class Main{
public static void main(String args[]){
certkiller("four");
certkiller("tee");
certkiller("to");
}
public static void certkiller(String str){
int check=4;
if(check==str.length())
System.out.print(str.charAt(check-=1));
else
System.out.print(str.charAt(0));
}
}
上述代码的运行结果为: 39.1
答案:
39.1: rtt
40.1 类实现了缓存功能的InputStream。
答案:
40.1: BufferedInputStream
在java.io包内包含了处理各种流的基本类,所有的字节输出流都继承于 41.1
类,所有的字符输入流都继承于 41.2 类。
答案:
41.1: OutputStream
41.2: Reader
InputStreamReader类是用于将( )转换为( )。 42.1 42.2
答案:
42.1: 字节流
42.2: 字符流
对于java.io包中的所有I/O类,根据数据流所关联的是数据源还是其他数据流,可分为节点流和 43.1 。
答案:
43.1: 处理流
调用线程对象的 44.1 方法可以启动线程,使线程处于可运行状态。
答案:
44.1: start()
Java程序中的线程被设计为一个对象,该对象具有自己的生命周期,可以利用接口Runnable和类 45.1 创建一个线程。
答案:
45.1: Thread
无论采用何种方式定义线程类,线程类中均需重新定义 46.1 方法,该方法负责完成线程所需执行的任务。
答案:
46.1: run()
在实现多线程的程序时有两种方式,一是通过继承( )类,二是通过实现( )接口。 47.1 47.2
答案:
47.1: Thread
47.2: Runnable
进程已结束,退出代码0
以下程序的功能是求一个二维数组中每行的最大值和每行的和。
输入样例
3
1 2 3
6 5 4
7 9 8
输出样例
1 2 3 3 6
6 5 4 6 15
7 9 8 9 24
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc=new Scanner(/*___1.1___*/);
int n=sc.nextInt();
int a[][]=new int[n][n];
int b[]=new int[n];
int c[]=new int[n];
for(int i=0;i<a.length;i++){
for(int j=0;j</*___1.2___*/;j++){
a[i][j]=sc.nextInt();
}
}
int max,s;
for(int i=0;i<a.length;i++){
max=a[i][0];
/*___1.3___*/;
for(int j=0;j<a[i].length;j++){
if(a[i][j]>max){
/*___1.4___*/;
}
s+=a[i][j];
}
b[i]=max;
c[i]=s;
}
for(int i=0;i<a.length;i++){
for(int j=0;j<a[i].length;j++){
System.out.printf("%3d",/*___1.5___*/);
}
System.out.printf("%3d%3d",b[i],c[i]);
System.out.println();
}
}
}
答案:
1.1 System.in
1.2 a[i].length
1.3 s=0
1.4 max=a[i][j]
1.5 a[i][j]
题目要求:
1.使用this调用已有的有参构造函数,width与length分别为5和6。
2.为Rectangle类覆盖toString。按照width=实际宽度值,length=实际长度值的格式输出
public Rectangle(){
/*___2.1___*/
}
public Rectangle(int width, int length) {
this.width = width;
this.length = length;
}
public /*___2.2___*/{
/*___2.3___*/
}
答案:
2.1 this(5,6); 或 this.width=5;this.length=6;
2.2 String toString()
2.3 return “width=”+width+“,length=”+length;
输入一行字符,请分别统计出英文字母、数字、空格和其他字符个数。
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
String str=sc.nextLine();
char x[]=/*___3.1___*/;
int a=0;
int b=0;
int c=0;
int d=0;
for(int i=0;/*___3.2___*/;i++){
char ch=x[i];
if(/*___3.3___*/)
a++;
else if(/*___3.4___*/)
b++;
else if(ch==' ')
/*___3.5___*/;
else
d++;
}
System.out.println("letters="+a);//输出英文字母个数
System.out.println("digits="+b);//输出数字个数
System.out.println("spaces="+c);//输出空格个数
System.out.println("others="+d);//输出其他字符个数
}
}
答案:
3.1 str.toCharArray();
3.2 i
3.3 ch>=‘a’&&ch<=‘z’ ||ch>=‘A’&&ch<=‘Z’
3.4 ch>=‘0’&&ch<=‘9’
3.5 c++
本题目要求t1线程打印完后,才执行主线程main方法的最后一句System.out.println(Thread.currentThread().getName()+" end");
public class Main {
public static void main(String[] args) throws InterruptedException {
Thread t1 = new Thread(new PrintTask());
/*___4.1___*/
/*___4.1___*/
System.out.println(Thread.currentThread().getName()+" end");
}
}
答案:
4.1 t1.start();
4.2 t1.join();
进程已结束,退出代码0