沈师 Java程序设计 PTA 填空题、程序填空题答案
無答案版鏈接:https://blog.csdn.net/a2272062968/article/details/117787974
文章目錄
- 填空題
- 程序填空題
填空題
?????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
假設輸入是 2 3 4 5 0,程序輸出是:
max is ?????2.1?????
number ?????2.2?????
答案:
2.1: 5
2.2: 0
After executing line 2, where will the program jump to??????3.1?????
答案:
3.1: 4
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
程序運行結果為:?????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,創建一個包即打包操作,應使用關鍵詞?????6.1?????
,該關鍵詞引導的語句必須放在程序的第?????6.2?????
行,該行前只能有空格及注釋。
在Java程序中,想要導入不同包下面的某個類時,可以使用關鍵詞?????6.3?????
答案:
6.1: package
6.2: 一
6.3: import
閱讀下列程序:
從下面選項中進行選擇,將相應序號(1、2、3、4、5中選其一)填入空格中:
(1)完成Person的任務
(2)完成Employee的任務
(3)完成Faculty的任務
(4)調用Employee的重載構造方法
(5)創建一個Faculty對象
按程序執行順序輸出結果:?????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
程序運行結果是:?????8.1?????
答案:
8.1: 0123454321
Java的三大體系分別是封裝、( )、( )。?????9.1??????????9.2?????
答案:
9.1: 繼承
9.2: 多態
給出以下代碼:
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"); } }程序運行后輸出結果為:?????10.1?????
答案:
10.1: 7ok
定義在類中的變量被稱為( ),定義在方法中的變量被稱為( )。?????11.1??????????11.2?????
答案:
11.1: 成員變量
11.2: 局部變量
訪問父類的成員可以使用?????12.1?????關鍵字。
答案:
12.1: super
說出下列A類中【代碼1】~【代碼3】的輸出結果
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);//【代碼1】Lake lake=new Lake();lake.setFish(redFish); lake.foodFish(120); System.out.println(redFish.weight);//【代碼2】 System.out.println(lake.fish.weight);//【代碼3】 } }【代碼1】?????13.1?????
【代碼2】?????13.2?????
【代碼3】?????13.3?????
答案:
13.1: 1
13.2: 121
13.3: 121
閱讀以下程序,寫出輸出結果。
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"); } }程序運行后輸出: 從下列選項中選,在空格處填上相應的序號數字(1、2或3)
(1)This is a phone
(2)This is a Apple mobile phone
(3)This is a mobile phone
第一行輸出:?????14.1?????
第二行輸出:?????14.2?????
第三行輸出:?????14.3?????
答案:
14.1: 1
14.2: 3
14.3: 2
請說出A類中System.out.println的輸出結果。
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()); } }程序輸出結果為:sum=?????15.1?????
答案:
15.1: -100
已知代碼:
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());} }在下列運行結果的空格中選擇填寫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
閱讀下列程序:
class Animal{Animal(){ System.out.println("我是動物"); }void shout(){ System.out.println("動物叫"); } } 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();} }按程序執行順序輸出結果:
(1)?????17.1?????
(2)?????17.2?????
(3)?????17.3?????
(4)?????17.4?????
(5)?????17.5?????
答案:
17.1: 我是動物
17.2: 我是動物
17.3: 動物叫
17.4: 汪汪
17.5: 喵喵
閱讀以下程序,在空格內填上正確答案。
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;} }程序運行后,輸出:
number is?????18.1?????
and numbers[0] is?????18.2?????
答案:
18.1: 0
18.2: 3
閱讀下列程序:
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(); } }程序運行后依次輸出:?????19.1??????????19.2??????????19.3?????
答案:
19.1: i=40
19.2: i=60
19.3: i=60
請寫出以下程序運行結果:
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
請寫出以下程序運行結果:
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()
接口中的方法的默認的訪問權限是?????22.1?????。
答案:
22.1: public
已知代碼:
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");elseSystem.out.println("md1!=md2");if(md1.equals(md2))System.out.println("md1 is equla to md2");elseSystem.out.println("md1 is not equal to md2");} }運行上述代碼,寫出其運行結果:?????23.1??????????23.2?????
答案:
23.1: md1!=md2
23.2: md1 is not equal to md2
用?????24.1?????關鍵字修飾的類不能被繼承。
答案:
24.1: final
請寫出以下程序運行結果:
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
運行下列代碼,運行結果是什么?
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);} }運行上述代碼,則運行結果為:?????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
一個類如果實現一個接口,那么它就需要實現接口中定義的全部( ),否則該類就必須定義成( )。?????27.1??????????27.2?????
答案:
27.1: 方法
27.2: 抽象類
給出以下代碼:
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); } }程序運行后輸出結果是:?????28.1?????
答案:
28.1: 9:10
下列代碼的運行結果是什么?
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();} }上述代碼的運行結果為:?????29.1?????
答案:
29.1: Hi here,HelloHello
請寫出以下程序運行結果:
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
請寫出以下程序運行結果:
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
請寫出以下程序運行結果:
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,用戶自定義異常類必須繼承?????33.1?????
類, 用戶人工拋出自定義異常使用關鍵詞?????33.2?????。
答案:
33.1: Exception
33.2: throw
在Java中,?????34.1?????類是所有異常和錯誤的頂級父類。
答案:
34.1: Throwable
當編譯并運行下列代碼時,其運行結果是什么?
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";} }上述代碼的運行結果為:?????35.1?????
答案:
35.1: Hallo
當編譯并運行下列代碼時,其運行結果是什么?
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");} }上述代碼的運行結果為:?????36.1?????
答案:
36.1: JavaJavaHello
給出以下代碼:
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); } }程序運行輸出結果是:?????37.1?????
答案:
37.1: 0B
當編譯并運行下列代碼時,其運行結果時什么?
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();} }上述代碼的運行結果為:?????38.1?????
答案:
38.1: JavaAJava
當編譯并運行下列代碼時,其運行結果是什么?
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));elseSystem.out.print(str.charAt(0));} }上述代碼的運行結果為:?????39.1?????
答案:
39.1: rtt
?????40.1?????類實現了緩存功能的InputStream。
答案:
40.1: BufferedInputStream
在java.io包內包含了處理各種流的基本類,所有的字節輸出流都繼承于?????41.1?????
類,所有的字符輸入流都繼承于?????41.2?????類。
答案:
41.1: OutputStream
41.2: Reader
InputStreamReader類是用于將( )轉換為( )。?????42.1??????????42.2?????
答案:
42.1: 字節流
42.2: 字符流
對于java.io包中的所有I/O類,根據數據流所關聯的是數據源還是其他數據流,可分為節點流和?????43.1?????。
答案:
43.1: 處理流
調用線程對象的?????44.1?????方法可以啟動線程,使線程處于可運行狀態。
答案:
44.1: start()
Java程序中的線程被設計為一個對象,該對象具有自己的生命周期,可以利用接口Runnable和類?????45.1?????創建一個線程。
答案:
45.1: Thread
無論采用何種方式定義線程類,線程類中均需重新定義?????46.1?????方法,該方法負責完成線程所需執行的任務。
答案:
46.1: run()
在實現多線程的程序時有兩種方式,一是通過繼承( )類,二是通過實現( )接口。?????47.1??????????47.2?????
答案:
47.1: Thread
47.2: Runnable
進程已結束,退出代碼0
程序填空題
以下程序的功能是求一個二維數組中每行的最大值和每行的和。
輸入樣例
3
1 2 3
6 5 4
7 9 8
輸出樣例
1 2 3 3 6
6 5 4 6 15
7 9 8 9 24
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]
題目要求:
1.使用this調用已有的有參構造函數,width與length分別為5和6。
2.為Rectangle類覆蓋toString。按照width=實際寬度值,length=實際長度值的格式輸出
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;
輸入一行字符,請分別統計出英文字母、數字、空格和其他字符個數。
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___*/;elsed++;}System.out.println("letters="+a);//輸出英文字母個數System.out.println("digits="+b);//輸出數字個數System.out.println("spaces="+c);//輸出空格個數System.out.println("others="+d);//輸出其他字符個數} }答案:
3.1 str.toCharArray();
3.2 i<x.length
3.3 ch>=‘a’&&ch<=‘z’ ||ch>=‘A’&&ch<=‘Z’
3.4 ch>=‘0’&&ch<=‘9’
3.5 c++
本題目要求t1線程打印完后,才執行主線程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();
進程已結束,退出代碼0
總結
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