import java.util.*;
public class T {
public static void main(String args]) {
Set set = new TreeSet();
set.add(new Integer(10));
set.add(new Integer(5));
set.add(new Integer(15));
set.add(new Integer(5));
set.add(new Integer(10));
System.out.println("size = " + set.size());
Iterator it=set.iterator();
while(it.hasNext()){
System.out.print(it.next()+" ");
}
}
}
1、程序运行后输出的结果如何？
2、说明java中的集合(Set接口)和映射(Map接口)的主要区别
以下文字与答案无关
提示：有些试题内容 显示不完整,文字错误 或者 答案显示错误等问题，这是由于我们在扫描录入过程中 机器识别错误导致,人工逐条矫正总有遗漏，所以恳请 广大网友理解。
ListIterator listIter = list.listIterator();
listIter.add(new Integer(0));
System.out.println("After add at beginning:"+list);
if ( listIter.hasNext() ) {
int i = listIter.nextIndex();
listIter.next();
listIter.set(new Integer(9));
System.out.println("After set at "+i+":"+list);}
if ( listIter.hasNext() ) {
int i = listIter.nextIndex();
listIter.next();
listIter.remove();
System.out.println("After remove at "+i+" : "+list);
}
">2.import java.util.*;public class ListIteratorDemo {
public static void main(String] args) {
List list = new ArrayList();
for(int i=1; i<5; i++){
list.add(new Integer(i));}
System.out.println("The original list : "+list);
ListIterator listIter = list.listIterator();
listIter.add(new Integer(0));
System.out.println("After add at beginning:"+list);
if ( listIter.hasNext() ) {
int i = listIter.nextIndex();
listIter.next();
listIter.set(new Integer(9));
System.out.println("After set at "+i+":"+list);}
if ( listIter.hasNext() ) {
int i = listIter.nextIndex();
listIter.next();
listIter.remove();
System.out.println("After remove at "+i+" : "+list);
}
s2 = new String();
s2 = "study hard.";
System.out.print(s1);
System.out.println(s2);
s2 = "learn english, too";
System.out.print(s1);
System.out.println(s2);
s2 = s1 + s2;
System.out.println(s2);
}
}
">3.6.阅读程序，写出运行结果public class StringUse {
public static void main(String] args) {
String s1, s2;
s1 = new String("Students should ");
s2 = new String();
s2 = "study hard.";
System.out.print(s1);
System.out.println(s2);
s2 = "learn english, too";
System.out.print(s1);
System.out.println(s2);
s2 = s1 + s2;
System.out.println(s2);
}
}
import java.io.*;
public class E {
public static void main(String args]) {
int n=-1;
File f =new File("hello.txt");
byte ] a="abcd".getBytes();
try{ FileOutputStream out=new FileOutputStream(f);
out.write(a);
out.close();
FileInputStream in=new FileInputStream(f);
byte ] tom= new byte3];
int m = in.read(tom,0,3);
System.out.println(m); //【代码1】
String s=new String(tom,0,3);
System.out.println(s); //【代码2】
m = in.read(tom,0,3);
System.out.println(m); //【代码3】
s=new String(tom,0,3);
System.out.println(s); //【代码4】
}
catch(IOException e) {}
}
}（2.0分）
byte ] a="abcd".getBytes();
try{ FileOutputStream out=new FileOutputStream(f);
out.write(a);
out.close();
FileInputStream in=new FileInputStream(f);
byte ] tom= new byte3];
int m = in.read(tom,0,3);
System.out.println(m); //【代码1】
String s=new String(tom,0,3);
System.out.println(s); //【代码2】
m = in.read(tom,0,3);
System.out.println(m); //【代码3】
s=new String(tom,0,3);
System.out.println(s); //【代码4】
}
catch(IOException e) {}
}
}
">5.上机调试题：请说出E类中标注的【代码1】～【代码4】的输出结果。
import java.io.*;
public class E {
public static void main(String args]) {
int n=-1;
File f =new File("hello.txt");
byte ] a="abcd".getBytes();
try{ FileOutputStream out=new FileOutputStream(f);
out.write(a);
out.close();
FileInputStream in=new FileInputStream(f);
byte ] tom= new byte3];
int m = in.read(tom,0,3);
System.out.println(m); //【代码1】
String s=new String(tom,0,3);
System.out.println(s); //【代码2】
m = in.read(tom,0,3);
System.out.println(m); //【代码3】
s=new String(tom,0,3);
System.out.println(s); //【代码4】
}
catch(IOException e) {}
}
}
}
}
class Rectangle extends Shape {
void display() { //实现抽象类的方法
System.out.println("Rectangle");
}
}
class Triangle extends Shape {
void display() { //实现抽象类的方法
System.out.println("Triangle");
}
}
public class AbstractClassDemo{
public static void main(String args]){
(new Circle()).display();//定义无名对象来调用对应的display方法
(new Rectangle()).display();
(new Triangle()).display();
}
}
输出结果是 ?
">6.阅读程序，给出结果：// AbstractClassDemo.java源代码如下：
abstract class Shape { //定义抽象类Shape和抽象方法display
abstract void display();
}
class Circle extends Shape {
void display() {//实现抽象类的方法
System.out.println("Circle");
}
}
class Rectangle extends Shape {
void display() { //实现抽象类的方法
System.out.println("Rectangle");
}
}
class Triangle extends Shape {
void display() { //实现抽象类的方法
System.out.println("Triangle");
}
}
public class AbstractClassDemo{
public static void main(String args]){
(new Circle()).display();//定义无名对象来调用对应的display方法
(new Rectangle()).display();
(new Triangle()).display();
}
}
输出结果是 ?
list.add("demo_2");
list.add("demo_3");
ListIterator it = list.listIterator();
while(it.hasPrevious()) {
Object obj = it.previous();
System.out.print(obj+" ");
}
}
}
">7.代码三：import java.util.*;
public class Test03 {
public static void main(String] args) {
ArrayList list = new ArrayList();
list.add("demo_1");
list.add("demo_2");
list.add("demo_3");
ListIterator it = list.listIterator();
while(it.hasPrevious()) {
Object obj = it.previous();
System.out.print(obj+" ");
}
}
}
System.out.println(" *** ");
System.out.println(" ***** ");
}
}
">8.阅读程序，写出下面程序运行结果。/* Practice1_1.java */
public class Practice1_1 {
public static void main(String] args) {
System.out.println(" * ");
System.out.println(" *** ");
System.out.println(" ***** ");
}
}
for (int i=0;i<list.length;i++)
System.out.print(listi]+" ");
System.out.println();
}
public static void main(String] args){
int] list1={0,1,2,3};
int] list2=new intlist1.length];
list2=list1;
PrintLst("数组1",list1);
PrintLst("数组2",list2);
list12]=list12]+10;
PrintLst("修改数组1后，数组2为",list2);
}}
">9.阅读下列程序，并给出程序运行的结果。public class CopyArray{
public static void PrintLst(String s,int] list){
System.out.print(s+":");
for (int i=0;i<list.length;i++)
System.out.print(listi]+" ");
System.out.println();
}
public static void main(String] args){
int] list1={0,1,2,3};
int] list2=new intlist1.length];
list2=list1;
PrintLst("数组1",list1);
PrintLst("数组2",list2);
list12]=list12]+10;
PrintLst("修改数组1后，数组2为",list2);
}}
}
}
选项： A:错误:方法参数与变量不匹配
B:20 and 40
C:10 and 40
D:10 and 20
">10.以下代码的输出结果为（ ）。public class Pass{
static int j = 20;
public void amethod(int x){
x = x*2;
j = j*2;
}
public static void main(String args]){
int i = 10;
Pass p = new Pass();
p.amethod(i);
System.out.println(i+" and "+j);
}
}
选项： A:错误:方法参数与变量不匹配
B:20 and 40
C:10 and 40
D:10 and 20
请说出E类中标注的【代码1.】~【代码4.】的输出结果()。(多个结果之间用#号隔开)。
Import java.io.*;
Public class E {
Public static void main(String args]) {
Int n=-1.;
File f =new File("hello.txt");
Byte ] a="abcd".getBytes();
Try{ FileOutputStream out=new FileOutputStream(f);
Out.write(a);
Out.close();
FileInputStream in=new FileInputStream(f);
Byte ] tom= new byte3.];
Int m = in.read(tom,0.,3.);
System.out.println(m); //【代码1.】
String s=new String(tom,0.,3.);
System.out.println(s); //【代码2.】
M = in.read(tom,0.,3.);
System.out.println(m); //【代码3.】
S=new String(tom,0.,3.);
System.out.println(s); //【代码4.】
}
Catch(IOException e) {}
}
}
New York, Atlanta]
C:New York, Atlanta, Dallas]
D:New York, Dallas]
">13.(单选题) 以下代码的输出结果是 __________ ? LinkedHashSet<String> set1 = new LinkedHashSet<>(); set1.add("New York"); LinkedHashSet<String> set2 = (LinkedHashSet<String>)(set1.clone()); set1.add("Atlanta"); set2.add("Dallas"); System.out.println(set2); 选项： A:New York]
B:New York, Atlanta]
C:New York, Atlanta, Dallas]
D:New York, Dallas]
Public class MyControl: UserControl{
public MyControl(){
TextBox textBox1=new TextBox();
Button button1=new Button();
button1.Top=textBox1.Height;
this.Controls.Add(textBox1);
this.Controls.Add(button1);
}}
B:Public class MyControl: UserControl{
TextBox textBox1=new TextBox();
Button button1=new Button();
button1.Top=textBox1.Height;
this.Controls.Add(textBox1);
this.Controls.Add(button1);
}
C:Public class MyControl: TextBox,Button{
public MyControl(){
TextBox textBox1=new TextBox();
Button button1=new Button();
button1.Top=textBox1.Height;
this.Controls.Add(textBox1);
this.Controls.Add(button1);
}}
D:Public class MyControl: TextBox,Button{
TextBox textBox1=new TextBox();
Button button1=new Button();
button1.Top=textBox1.Height;
this.Controls.Add(textBox1);
this.Controls.Add(button1);
}
}
public void printThat(int x,int y){
this.x = x;
this.y = y;
System.out.println("x:" + this.x + " y:" + this.y);
}
}
What is the result?
结果如何?
选项： A:x: 1 y: 2 x：3 y: 4
B:x: 0 y: 0 x: 3 y: 4
C:x: 1 y: 2 x: 0 y: 0
D:x: 0 y: 0 x: 0 y: 0
">15.public class Access {private int x = 0;
private int y = 0;
public static void main(String] args) {
Access accApp = new Access();
accApp.printThis(1,2);
accApp.printThat(3,4);
}
public void printThis(int x,int y){
x = x;
y = y;
System.out.println("x:" + this.x + " y:" + this.y);
}
public void printThat(int x,int y){
this.x = x;
this.y = y;
System.out.println("x:" + this.x + " y:" + this.y);
}
}
What is the result?
结果如何?
选项： A:x: 1 y: 2 x：3 y: 4
B:x: 0 y: 0 x: 3 y: 4
C:x: 1 y: 2 x: 0 y: 0
D:x: 0 y: 0 x: 0 y: 0
