1.下面程序的运行结果是（ ）。
public class E3{
public static void main(String args[]){
String s="大大";
char a=s.charAt(2),b=s.charAt(4);
System.out.print(a);
System.out.println(b);
}
}
2.下面程序的运行结果是（ ）。
import java.util.*;
public class LinkedListExample {
public static void main(String args[]){
LinkedList linkedlist = new LinkedList();
linkedlist.add(new Integer(1));
linkedlist.add(new Integer(2));
linkedlist.add(new Integer(3));
linkedlist.add(new Integer(4));
linkedlist.add(new Integer(5));
System.out.println("The original contents of the linkedlist is: ");
System.out.println(linkedlist);
linkedlist.add(2,"hello");
linkedlist.addFirst("First");
linkedlist.addLast("Last");
System.out.println("After adding elements，the linkedlist is: ");
System.out.println(linkedlist);
}
}
答：
3.下面程序的运行结果是（ ）。
public class TestArray {
public static void main(String args[]) {
int i, j;
int a[] = { 5, 9, 6, 8, 7 };
for (i = 0; i < a.length-1; i++) {
int k = i;
for (j = i; j < a.length; j++)
if (a[j] < a[k])
k = j;
int temp = a[i];
a[i] = a[k];
a[k] = temp;
}
for (i = 0; i < a.length; i++)
System.out.print(a[i] + " ");
System.out.println();
}
}
4.下面程序的运行结果是（ ）。
public class TryCatchFinally {
static void Proc(int sel) {
try {
if (sel == 0) {
System.out.println("no Exception ");
return;
} else if (sel == 1) {
int i = 0;
int j = 4 / i;
}
} catch (ArithmeticException e) {
System.out.println("Catch ");
} catch (Exception e) {
System.out.println("Will not be executed");
} finally {
System.out.println("finally");
}
}
public static void main(String args[]) {
Proc(0);
Proc(1);
}
}
5.下面程序的运行结果是（ ）。
public class welcomeTest {
public static void main(String[] args) {
String s, s1 = "";
char c;
s = "wELCOME";
for (int i = 0; i < s.length(); i++) {
c = s.charAt(i);
if (c >= 'a' && c <= 'z') {
s1 = s1 + UpperCase(c);
} else {
s1 = s1 + LowerCase(c);
}
}
System.out.println(s1);
}
}
6.下面程序的运行结果是（ ）。
public class arrTest {
public static void main(String args[]) {
int i, j;
int a[] = {2, 1, 4, 8};
for (i = 0; i < a.length - 1; i++) {
int k = i;
for (j = i; j < a.length; j++)
if (a[j] < a[k])
k = j;
int temp = a[i];
a[i] = a[k];
a[k] = temp;
}
for (i = 0; i < a.length; i++)
System.out.print(a[i] + " ");
System.out.println();
}
}
7.下面程序的运行结果是（ true,false）。
public class StringTest {
public static void main(String args[]) {
String s1 = new String("abcde");
String s2 = new String("abcde");
boolean b1 = s1.equals(s2);
boolean b2 = s1 == s2;
System.out.print(b1 + "," + b2);
}
}
8.下面程序运行时，若输入10，则输出结果是（ ）。
public class test {
public static void main(String args[]) throws IOException {
BufferedReader buf = new BufferedReader(
new InputStreamReader(System.in));
while (true) {
String str = adLine();
if (str.equals("quit"))
break;
int x = Integer.parseInt(str);
System.out.println(x * x);
}
System.out.println(“OK”);
}
}
9.下面程序的运行结果是（ ）。
public class T {
public static void main(String args[]) {
Set set = new HashSet();
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.() + " ");
}
}
}
10.下面程序的运行结果是（ ）。
public class A {
class Dog {
private String name;
private int age;
public int step;
Dog(String s, int a){
name = s;
age = a;
step = 0;
}
public void run(Dog fast){
fast.step++;
}
}
public static void main(String args[]){
A a = new A();
Dog dog = a.new Dog("Tom", 3);
dog.step = 25;
dog.run(dog);
System.out.println(dog.step);
}
}
11.下面程序的运行结果是（ ）。
class A {
int x=1, y=2;
double add(){ return x+y; }
}
class B extends A{
int x=10, y=20;
double add(){ return super.x + super.y; }
}
class Takecare {
java库 public static void main(String[] args){
A a = new A();
B b = new B();
System.out.println("a.add="+a.add());
System.out.println("b.add="+b.add());
}
}
12.下面程序的运行结果是（ ）。
for (int i = 0; i < 5; i++) {
switch (i) {
default:
System.out.print("default\t");
case 0:
System.out.print("zero\t");
i++;
break;
case 1:
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