SCJP认证试题(九)

Place the correct Code in the Code Sample to achieve the expected results.
Expected results:
Output :1 2 4 8 16 32
Code Sample

int[] y = {1,2,4,8,16,32};
		System.out.print("Output:");
		[place here]
		System.out.print(x);
		System.out.print("");
		}

Code
[for(int x:y){] [for(int x=y[]){] [foreach(y as x){] [foreach(int x:y){]       [for(int x=1;x=y[];x++)]


Answer:

int[] y = {1,2,4,8,16,32};
		System.out.print("Output:");
		for(int x:y){
		System.out.print(x);
		System.out.print("");
		}

8	public class Test{
9		public static void main(String[] a){
10			assert a.length == 1;
11		}
12	}

Which two will produce an AssertionError?(choose two)


A java test
B java -ea test
C java test file1
D java -ea test file1
E java -ea test file1 file2
F java -ea:test test file1

Answer : B E

84	try{
85		ResourceConnection con = resourceFactory.getConnection();
86		Results r = con.query("GET INFO FROM CUSTOMER");
87		info = r.getData();
88		con.close();
89		}catch(ResourceException re){
90			errorLog.write(re.getMessage());
91		}
92		return info;

Which statement is true if a ResouceException is thrown on line 86?

A Line 92 will not execute
B The connection will not be retrieved in line 85
C The resource connection will not be closed on line 88
D The enclosing method will thrown an exception to its caller



Answer : C


Assuming that the serializeBanana() and the deserializeBanana() methods will correctly use Java serialization and given:

13	import java.io.*;
14	class Food implements Serializable{int good = 3;}
15	class Fruit extends Food{int juice = 5;}
16	public class Banana extends Fruit{
17		int yellow = 4;
18		public static void main(String[] args){
19			Banana b = new Banana();
20			b.serializeBanana(b);
21			b2 = b.deserializeBanana();
22			System.out.println("restore" + b2.yellow + b2.juice + b2.good);
23		}
24		//more Banana methods go here
25

What is the result?

A restore 400
B restore 403
C restore 453
D Compilation fails
E An exception is thrown at runtime



Answer : C


Given :

	12 System.out.format("Pi is approximately %d", Math.PI);

What is the result?

A Compilation fails
B Pi is approximately 3.
C Pi is approximately 3.141593
D An exception is thrown at runtime



Answer : D

11	public class Yikes{
12
13	public static void go(Long n){System.out.println("Long ");}
14	public static void go(Short n){System.out.println("Short ");}
15	public static void go(int n){System.out.println("int ");}
16	public static void main(String[] args){
17		short y = 6;
18		long z = 7;
19		go(y);
20		go(z);
21	}
22	}

What is the result?

A int Long
B Short Long
C Compilation fails
D An exception is thrown at runtime

Answer : A



Given this method in a class:

21	public String toString(){
22		StringBuffer buffer = new 	StringBuffer();
23		buffer.append('<');
24		buffer.append(this.name);
25		buffer.append('>');
26		return buffer.toString();
27	}

Which statement is true?


A This code is NOT thread-safe
B The programmer can replace StringBuffer with StringBuilder with no other changes
C This code will perform poorly.For better performance,the code should be rewritten:return "<" + this.name + ">";
D This code will perform well and converting the code to use StringBuffer will not enchange the performance



Answer: B



Given :

33	Date d = new Date(0);
34	String ds = "December 15, 2004";
35	// insert code here
36	try{
37		d = df.parse(ds);
38	}
39	catch(ParseException e){
40		System.out.println("Unable to parse " + ds);
41	}
42	// insert code here too

What creates the approprivate DateFormat object and adds a day to the Date object?

A 35.DateFormat df = DateFormat.getDateFormat();
42.d.setTime((60*60*24) + d.getTime());
B 35.DateFormat df = DateFormat.getDateInstance();
42.d.setTime((1000*60*60*24) + d.getTime());
C 35.DateFormat df = DateFormat.getDateFormat();
42.d.setLocalTime((1000*60*60*24) + d.getLocalTime());
D 35.DateFormat df = DateFormat.getDateInstance();
42.d.setLocalTime((60*60*24) + d.getLocalTime());



Answer: B




Given :

12	NumberFormat nf = NumberFormat.getInstance();
13	nf.setMaxinumFractionDigits(4);
14	nf.setMininumFractionDigits(2);
15	String a = nf.format(3.1415926);
16	String b = nf.format(2);

Which two statements are true about the result if the locale is Locale.US?(Choose two)


A The value of b is 2
B The value of a is 3.14
C The value of b is 2.00
D The value of a is 3.141
E The value of a is 3.1415
F The value of a is 3.1416
G The value of b is 2.0000.


Answer: C F

1	import java.util.*;
2	public class Old{
3		public static Object get0(List list){
4			return list.get(0);
5		}
6	}

Which three will compile successfully?(Choose three)


A Object o = Old.get0(new LinkedList());
B Object o = Old.get0(new LinkedList<?>());
C String s = Old.get0(new LinkedList<String>());
D Object o = Old.get0(new LinkedList<Object>());
E String s = (String)Old.get0(new LinkedList<String>());
F


Answer: A D E