Java基础强化练习题2(附答案)

B. SELECT DISTINCT(cid) FROM ORDERS o1,orders o2 WHERE o1.pid=’p01’ AND o2.pid=’p02’ AND o1.cid=o2.cid
C. SELECT DISTINCT(cid) FROM orders WHERE pid=’p01’ AND cid IN(select cid FROM orders WHERE pid=’p02’)
………
}
}
下列代码段没有编译错误的是：（）。
A.
class B extends A {
public void f() throws Exception {
………
}
}
B.
class B extends A {
public void g() throws IOException {
f();
}
}
C.
class B extends A {
C.
select a1.real_name customer, a2.real_name recommenderfrom account a1 join account a2on a1.recommender_id = a2.id;
D.
select a1.real_name customer, a2.real_name recommenderfrom account a1, a2on a1.recommender_id = a2.id;
B. new InputStreamReader(new FileInputStream(“fileName”));
C. new BufferedReader(new InputStreamReader(new FileInputStream(“fileName”)));
D. new RandomAccessFile(“fileName”,”+rw”);
throw new RuntimeException(e);
}
}
}
正确答案：D
分析：子类重写父类的方法时候不能声明抛出比父类大的异常
5.
A. INSERT
B. SUBSTR
C. LPAD
D. LEAST
正确答案：B
6. ResultSet
A. getNumber()
B. getDouble()
C. setNumber()
A. java.sql.Connection
B. java.sql.Driver
C. java.sql.DriverManager
D. java.sql.ResultSet
正确答案：C
3. synchronized
A.方法上
B.接口上
C.变量上
D.类上
正确答案：A
4.
class A {
protected void f() throws FileNotFoundException {
System.out.print(index + "");
index += str1.length();
}
}
控制台输出的结果是：（）。
A. 1 10 21
B. 2 11 22
C. 3 13 23
D. 5 13 22
正确答案：B
11.
A. String st1 = "abc";
System.out.println("abc" == st1);
B. String st2 = "abc";
System.out.println(st2.equals(new String("abc")));
C. Integer i = 100;
System.out.println(100 == i);
D. ArrayList list = new ArrayList();
D. SELECT DISTINCT(cid) FROM orders o1,orders o2 WHERE o1.pid=’p01’ AND o2.pid=’p02’
正确答案：C
20.
A. Connection的commit()
B. Connection的setAutoCommit()
C. Connection的rollback()
}
}
class B extends A {
void process() {
System.out.println("B ");
}
}
A.输出:B
B.无输出
C. B类的process方法处，出现编译错误
D.代码a.process();行，出现编译错误
正确答案：D
8.
public static void main(String[] args) {
C. throws用来表示一个方法有可能抛出异常给上一层，则在调用该方法时必须捕捉异常，否则无法编译通过
D. main方法不可以使用throws抛出异常
正确答案：D
19.
A. SELECT DISTINCT(cid) FROM orders o1 WHERE o1.pid IN(‘p01’,’p02’)
正确答案：A
16.
A.
select a1.real_name customer, a2.real_name recommenderfrom account a1 join account a2on a1.id = a2.id;
B.
select a1.real_name customer, a2.real_name recommenderfrom account a1 join account a2on a1.recommender_id = a2.recommender_id;
正确答案：D
15.
public class Foo {
public static void main(String[] args) {
try {
test();
System.out.println("condition 1");
} catch (ArrayIndexOutOfBoundsException e) {
System.out.println("condition 2");
} catch (Exception e) {
System.out.println("condition 3");
} finally {
System.out.println("finally");
}
}
public static void test() {
public void g() {
try{
f();
………
}
catch(IOException e) {
………
}
catch(FileNotFoundException e1) {
………
}
}
}
D.
class B extends A {
public void g() {
try {
f();
}
catch(FileNotFoundException e) {
正确答案：C
17.
public class Forest implements Serializable {
private Tree tree = new Tree();
public static void main(String[] args) {
Forest f = new Forest();
try {
正确答案：C
10.
public static void main(String[] args) {
String str = "**oracle***oracle*****oracle***";
String str1 = "oracle";
int index = 0;
while ((index = str.indexOf(str1, index)) != -1) {
FileOutputStream fs = new FileOutputStream("Forest.ser");
ObjectOutputStream os = new ObjectOutputStream(fs);
os.writeObject(f);
os.close();
} catch (Exception ex) {
D. ResultSet的的方法getString（...）意为取得该列的数据以字符串的形式返回，数据库中的该列类型并不一定必须是字符类型
正确答案：A
13.
A. COMMIT
ቤተ መጻሕፍቲ ባይዱB. INSERT
C. DROP
D. GRANT
正确答案：B
14.
A.事务具备ACID四个基本特性，即A（Atomicity）—原子性、C（Consistency）—一致性、I（Isolation）—隔离性、D（Durability）—持久性。
Float pi = new Float(3.14f);
if (pi > 3) {
System.out.print("pi is bigger than 3. ");
} else {
System.out.print("pi is not bigger than 3. ");
}
finally {