IKM

Q1 🚀

Which of the following techniques can a Java SE programmer use to increase the thread safety of a program?

a. Use public static variables

b. Write classes so they are immutable

c. Use ThreadLocal variables

d. Use Final classes

e. Annotate a class with @Multithread

答案: bc

这题考的是java线程安全的理解。只有有状态的对象才会有线程安全问题。通常解决线程安全的方法有两个：

• 加锁顺序访问关键资源(牺牲时间）
• 每个线程单独一个资源副本(牺牲空间）

其中b的意思将类写为不可变的，就是没状态的，从根本上解决问题。

c是第2种解决方案

a 是制造线程安全隐患

d.只是令到类不能被继承

e. 我没见过@Mutithread 这注解

immutable: 美[ɪˈmjuːtəbl], adj. 不可改变的

Q2 🚀

Under which of the following conditions will an alert message be displayed for the Javascript code given below？

<form name="frm">
	<label for="age">Please enter your birthday</label>
	<input type ="text" name="age" id="age" onblur="validate(this.value)"/>
	<input type="submit" id="Enter"/>
</ form>
<script language ="javascript">
    function validate(val) {
        if (isNaN(val) {
            alert("XXX XXX XXX");
            document.frm.age.focus();
        }
    }
</script>

a. If the text box age contains a numerical value and the submit button Submit is clicked

b. If textbox age loses focus and contains a non-numerical value

c. If textbox age contains a non-numerical value and gains focus

d. If textbox age contains a non-numerical value and the submit button Enter is clicked

e. If textbox age loses focus and contains a numerical value

答案：b

这题问的是那种情况下会有alert message 弹出，考的是基本J2EE 知识

在HTML5 中, onblur 和 onfocus 是事件属性，onblur（失去焦点）， onfocus（获取焦点）

考点1, onblur事件， 可以理解为失去元素focus的事件， 一般用于验证用于在元素上的输入

考点2, isNaN() 判断是否为numeric的函数。NaN -> Not a number, 所以isNaN对数字类的参数返回值是False

numerical: 美[nuːˈmerɪkl] adj.数字的;用数字表示的;

• Calculate a numerical minimum or maximum
• 计算数字的最小值和最大值

gains: 美[ɡeɪnz] v. 获得;得到(好处);取得; n. (尤指财富、重量的)增值，增加;利益;利润;好处;改进;经济收益; gain的第三人称单数和复数;

• That an enterprise gains maximum business value from its data and data systems.
• 企业能够从它的数据和数据系统获得最大的业务价值。

Q3 🚀

A JavaEE servlet uses the line of code below:

String targetEmailForRequest = getServletConfig().getInitParameter(“corporateEmail”);

From which of the following locations will the application read the corporate Email value?

a. An attribute corporate Emailasteri in the request

b. A <servlet-mapping> element in web.xml

c. A corporateEmail entity in properties.xml

d. An <init-param> element in web.xml

e. A corporateEmail item in the session

答案：d

这题厉害了， 考的是servlet的知识。问题是上的面的代码是从哪里读取 corporateEmail 的值。

既然是getInitParameter，从答案都猜得出是d

corporate: 美[ˈkɔːrpərət] adj. 公司的; n.合伙公司;(由若干企业或公司组成的)集团;

• Many corporate methods have been adopted by American managers in imitation of Japanese practice.
• 美国的管理人员效仿日本人的做法，采用了很多经营公司的方法。

Q4 😭

Which of the following statements correctly describe lightweight and heavyweight Java Swing components?

a. Lightweight components are faster in response and performance

b. JWindow, JFrame , JDialog and JApplet are lightweight components

c. Heavyweight components provide a consistent look and feel on all platforms

d. Heavyweight components depend on native code counterparts to handle their functionality

e. AWT components are heavyweight, whereas Swing components are lightweight

答案：ade

一般的swing组件都是从awt组件继承的，swing是轻量组件没有本地peer跟他对应。而awt是重量组件，每个组件都有一个本地peer。这就是为什么swing组件在大多数系统上显示都差不多而awt就反之了。

AWT是通过调用操作系统的native方法实现的，所以在Windows系统上的AWT窗口就是Windows的风格，而在Unix系统上的则是XWindow风格。

Swing是所谓的Lightweight组件，不是通过native方法来实现的，所以Swing的窗口风格更多样化。但是,Swing里面也有heaveyweight组件。比如JWindow、Dialog、JFrame

a. 是正确的。

b. 他们是heavyweight的

c. 错误， 参考上面的黄色highlight解析

d.正确

e.正确

lightweight: adj. 美[ˈlaɪtweɪt] 轻量的

heavyweight n. 美[ˈheviweɪt] 重量级的

functionality： 美[ˌfʌŋkʃəˈnæləti] n. (计算机或电子系统的)功能

consistent ：美[kənˈsɪstənt] adj. 一致的;

• These actions are consistent with his principles.
• 这些行为与他的原则是一致的。、

whereas: 美[ˌwerˈæz] conj. (用以比较或对比两个事实)然而，但是，尽管;

• The research of image and video is very important whereas their characteristic.
• 鉴于图象和视频数据的这些特点，对图象和视频的研究就显得尤为重要。

counterparts: 美[ˈkaʊntərˌpɑrts] n. 职位(或作用)相当的人;对应的事物; counterpart的复数;

• They look enviously at the success of their European counterparts.
• 他们看着欧洲同行的成功，羡慕不已。

Q5 🚀

Which of the following can be returned in the variable result from invoking the below Java SE code?

java.util.Random r = new java.util.Random();
int result = r.nextInt(7);

a. 3

b. -1

c. 1234567

d. 7

e. 0

答案：a,e

这题考的是Random类的nextInt()函数。nextInt()里的参数是bound 边界，nextInt(7) 代表在0到6的数字里随机选1个。

bound: 美[baʊnd] n.跳跃;蹦跳; v.跳跃着跑;形成…的边界(或界限);束缚; adj.有义务(做某事);一定会;受(法律、义务或情况)约束(必须做某事);词典

bind的过去分词和过去式;

Research of Stock Index in Bias and Bound Characteristics.

股指波动的偏向性和跳跃性特征研究。

Q6 🚀

Which of the following statements regarding the usage of the Java SE this() and super() keywords are valid?

a. If used, this() or super() calls must always be the first statements in a constructor

b. this() and super() can be used in the same (non-constructor) method

c. If neither this() nor super() is coded then the compiler will generate a call to the zero argument superclass constructor

d. this() and super() calls can be used in methods other than a constructor

e. this() and super() can be used in the same constructor

答案: a, c

这题就厉害了，考的是this() 和 super()的用法，注意不是this.xxx 和 super.xx。

this.xxx -> 访问本对象的其他成员，super.xxx -> 访问父类的成员，极少会使用， 如果未初始化默认值为null。

参考： https://www.runoob.com/w3cnote/the-different-this-super.html

而this() 和 super()都用于构造函数，this() -> 调用本类其他参数类型的构造函数，super() -> 调用父类的构造函数，都只能写在构造函数的第一行。

调用super()必须写在子类构造方法的第一行，否则编译不通过。

每个子类构造方法的第一条语句，都是隐含地调用 super()(调用supper() or this())，如果父类没有这种形式的构造函数，那么在编译的时候就会报错。

this() 和 super() 不能同时出现在一个构造函数里面，因为this()必然会调用其它的构造函数，其它的构造函数必然也会有 super() 语句的存在，所以在同一个构造函数里面有相同的语句，就失去了语句的意义，编译器也不会通过。

regarding: 美[rɪˈɡɑːrdɪŋ] prep.关于;至于;

• She has said nothing regarding your request.
• 关于你的要求，她什么也没说。

other than：美[ˈʌðər ðæn] 除了…以外，除了…以外，除外;不同，不同于，不;

• Other than blowing up a tyre I hadn't done any car maintenance.
• 除了给轮胎充气外，我没做过任何汽车保养。

tyre: 美[ˈtaɪər] n.轮胎; v.装轮胎;

• That back tyre needs changing.
• 那个后轮胎需要更换。

blowing: 美[ˈbloʊɪŋ] v. 吹;刮;(被)刮动，吹动; n.吹制；吹气法;

blow的现在分词;

• The winds of change are blowing across the country.
• 改革之风吹遍全国。

Q7 😭

Which of the following statements are true about variable access between a Java SE inner class and its containing class?

c. The inner class can access private variables in the containing class

d. The containing class cannot access public variables in the inner class

Q8 😭

In JavaEE environment, which of the following statements are valid concerning the choice of a JDBC driver to access a database?

• Type-1 Bridge driver

• Type-2 Native API

• Type-3 Network Protocol

• Type-4 Native Protocol

a. Type 2 drivers have been deprecated since J2SE 5.0 and so should not be chosen

b. Type 4 drivers exist for MySQL, Oracle, SQL Server and DB2

c. A type1 driver will perform slightly faster than type2 driver

d. A type3 driver does not support calls to stored procedures

e. Type 4 drivers have the fastest performance but require the installation of software on the client

f. Which is vendor indepenedent – type

答案: b

• Type 1 需要桥接ODBC(安装在windowsODBC那玩意），所以又叫桥接驱动

• Type 2 本地API，需要安装本地的API(Lib)于数据库通讯

• Type 3 网络协议，需要1个中间(Vendor)app中间层去处理通讯

• Type 4 本地协议，不需要安装任何client软件，也叫瘦驱动，性能最好。我们现在用的基本上都是Type4驱动(只需要引入java编写的驱动jar包）

concerning: 美[kənˈsɜːrnɪŋ] prep.关于，涉及;

• The chairman's report is concerning the education of children.
• 主席的报告是关于儿童教育。

choice 美[tʃɔɪs] n. 选择;抉择;挑选;选择权; adj.优质的;优选的;上等的;

• Students have little or no choice in the matter.
• 学生在这个问题上很少有或没有选择余地。

Q9 🚀

What will be the output of the following code snippet?

import java.util.*;
public class LinkEx {
    public static void main(String args[]) {
        Set<String> set = new LinkedHashSet<String>();
        set.add("3");
        set.add("1");
        set.add("3");
        set.add("2");
        set.add("3");
        set.add("1");
        for (Iterator<String> it = set.iterator(); it.hasNext();) {
            String str = (String) it.next();
            System.out.print(str + "-");
        }
    }
}

a. 3-1-2-

b. An exception will be thrown at runtime

c. 1-2-3-

d. 3-1-3-2-3-1-

e. The program will run to completion, but the output will vary depending on the JVM

答案: a

说明：‌LinkedHashSet 是有序的‌。LinkedHashSet 通过维护一个双向链表来记录元素的顺序，确保元素按照插入的顺序进行存储和遍历。这意味着当你向LinkedHashSet 中添加元素时，这些元素的顺序会被保留下来，并且在遍历或获取元素时，元素的顺序与添加时的顺序一致。‌

snippet: 美[ˈsnɪpɪt] n.一小段

• Now, edit a small snippet of code in your custom language ( see Listing 3).
• 现在，用您定制的语言编写一小段代码（见清单3）。

vary：美[ˈveri] v. 变化;不同;

• The prices of fish vary according to market conditions.
• 鱼的价格随着市场行情而变化。

Q11 🚀

A Java SE class, MyFileProcessor, opens and uses a FileReader object in response to calls by its clients. Which of the following techniques could be used so that a client can guarantee that the FileReader object is closed at a certain point?

a. The client sets its MyFileProcessor object reference to null

b. The client makes a call to System.gc()

c. MyFileProcessor contains code to close files in its destructor

d. MyFileProcessor contains code to close the FileReader in its finalizer

e. MyFileProcessor includes a public closeFiles method that contains code to close the files. The client calls this method

答案: e

a 是泄露内存的典型

b 跟a差不多

c,d 意思是关闭资源 在 这个MyFileProcessor对象被回收时， 但是不能确定什么时候这个对象被jvm释放回收

e 是直接调用MyFileProcessor对象的close file方法。

techniques：美[tɛkˈniks] n.技术; technique的复数;

• The new management techniques aim to improve performance.
• 新的管理技术旨在提高效率。

guarantee: 美[ˌɡærənˈtiː] n.保证;担保; v.保证;

• He gave me a guarantee that it would never happen again.
• 他向我保证这种事情绝不会再发生。

certain: 美[ˈsɜːrtn] pron.(不提及人或事物的名称时用)某些; adj.确定;

• Certain of those present were unwilling to discuss the matter further.
• 某些在场的人不愿意进一步讨论这个问题。

Q12 😭

The role of Spring in a full fledged Spring Web application is which of the following?

a. It provides only an application-tier and data-tier logic web application framework,while the presentation-tier logic is left to itself

b. It provides only a presentation-tier Web application framework, while the application-tier and data-tier logic is left to itself

c. It provides the domain logic which implements the business rules to be provided by the web application

d. It provides the management and configuration of business objects, enabling data access, integration, and presentation with simple POJOs

e. It does not provide support for a full-fledged Spring Web application, but provides the infrastructure to support third-party Web frameworks

答案：bd

fledged：美[fledʒd] adj.羽翼已丰的; v.（鸟）长羽毛; fledge（长羽毛）的过去分词和过去式;

• She was now a fully fledged member of the teaching profession.
• 她现在是完全合格的教师。

profession: 美[prəˈfeʃn] n.职业; 行业;

• His linguistic ability served him well in his chosen profession.
• 他的语言能力对他所选择的职业大有帮助。

is left to itself: 任其自生自灭

Q13 🚀

Which of the following will be the result of an attempt to compile and execute the Java SE code snippet below?

class ExceptionDemo {
    public static void main(String[] args) {
        for (int x=3, int y=0; x>y; x--, y++) {
            System.out.print(x+""+y+"");
        }
    }
}

a. The output is “3 1 0 2”

b. A compilation error will occur at line number 4

c. The output is “ 3 0 2 1 “

d. A compilation error will occur at line number 3

e. A runtime exception will occur

答案：D

for初始化，只能简单初始1个变量。

Q14 🚀

Which of the following can be the output of an attempt to compile and execute the Java SE code snippet

public class ExceptionDemo {
    public static void main(String[] args) {
        int x = 5, y = 0;
        try {
            try {
                System.out.println(x);
                System.out.println(x / y);
                System.out.println(y);
            } catch (ArithmeticException ex) {
                System.out.println("Inner Catch1");
                throw ex;
            }
        } catch (RuntimeException ex) {
            System.out.println("Inner Catch2");
            throw ex;
        } catch (Exception ex) {
            System.out.println("Outer Catch");
        } finally {
            System.out.println("Inner Finally");
        }
    }
}

5Inner Catch1Inner Catch2Inner FinallyException in thread "main" java.lang.ArithmeticException: / by zero

arithmetic: 美[əˈrɪθmətɪk] n.算术; adj.算术的，运算的;

• He's not very good at arithmetic.
• 他不太擅长算术。

ArithmeticException 是一个运行时异常，通常发生在数学运算中，当运算条件不满足时触发。例如，整数除以零时会抛出这个异常。

Q18 🚀

In Java SE, which of the following from the java.io package are concrete classes that can be instantiated?

PrintWriter

FilterInputStream

instantiate: /ɪns'tænʃɪet/ v.实例化;例示;

• Select the image that you want to instantiate and click Next.
• 选择想要实例化的映像并单击Next。

concrete: 美[ˈkɑːŋkriːt] n.混凝土; adj.确实的，具体的 vt.用混凝土覆盖;

• concrete class：具体类

• Wait for the concrete to go hard.

• 等待混凝土凝结。

Q19 🚀

Which of the following statements are correct about the java.util.Queue<E> interface in Java SE?

b. A Queue object orders its elements in a FIFO (First In First Out) manner

d. In a Queue object containing one or more elements, the element and remove methods both return the same element – head element

manner 美[ˈmænər] n.方式;方法;规矩;

• The manner in which the decision was announced was extremely regrettable.
• 宣布决定的方式非常令人遗憾。

Q21 🚀

Which of the following techniques can resolve an OutOfMemoryError in a Java SE application?

c. Increase the available JVM heap size.

d. Ensure that references to objects are released when they are no longer needed.

Q22 🚀

Two Java SE classes are declared as shown below:

public class Invoice {
    public static String formatId(String oldId) {
        return oldId + "_Invoice";
    }
}
public class SalesInvoice extends Invoice {
    public static String formatId(String oldId) {
        return oldId + "_SalesInvoice";
    }
}

Which of the following statements are true about attempts to use these classes?

a. Invoice invoice = new SalesInvoice();
System.out.println(invoice.formatId(“1234”));
Will output 1234_SalesInvoice

b. Invoice invoice = new Invoice();
System.out.println((SalesInvoice)Invoice.formatId(“1234”));
Will output 1234_SalesInvoice

c. Invoice invoice = new Invoice(); .
System.out.println(invoice.formatId(“1234”));
Will output 1234_Invoice

d. SalesInvoice invoice = new SalesInvoice();
System.out.println(Invoice.formatId(“1234”));
Will output 1234_SalesInvoice

e. SalesInvoice invoice = new SalesInvoice();
System.out.println(invoice.formatId(“1234”));
Will output 1234_Invoice
正确的是c

java中静态属性和静态方法可以被继承，但是没有被重写(overwrite)而是被隐藏.

1). 静态方法和属性是属于类的，调用的时候直接通过类名.方法名完成对，不需要继承机制及可以调用。如果子类里面定义了静态方法和属性，那么这时候父类的静态方法或属性称之为"隐藏"。如果你想要调用父类的静态方法和属性，直接通过父类名.方法或变量名完成，至于是否继承一说，子类是有继承静态方法和属性，但是跟实例方法和属性不太一样，存在"隐藏"的这种情况。

2). 多态之所以能够实现依赖于继承、接口和重写、重载（继承和重写最为关键）。有了继承和重写就可以实现父类的引用指向不同子类的对象。重写的功能是："重写"后子类的优先级要高于父类的优先级，但是“隐藏”是没有这个优先级之分的。

3). 静态属性、静态方法和非静态的属性都可以被继承和隐藏而不能被重写，因此不能实现多态，不能实现父类的引用可以指向不同子类的对象。非静态方法可以被继承和重写，因此可以实现多态。

a. 对象的类型 invoice 被定义了父类， 执行对象实际类型是子类， 但是这种情况下调用的仍然是父类的static 函数. 错误

b. 父类的对象不能被强转为子类的对象。 除非Invoice invoice = new Invoice() 改为 Invoice invoice = new SalesInvoice() 改为

c. 明显是正确的

d. System.out.println(Invoice.formatId(“1234”)); 这里直接调用类名调用静态方法， 所以调用的是父类的静态方法

e. 这里应该调用的是子类的静态方法， 因为引用类型和对象类型都是子类

Q23 🚀

Java SE class ThirdPartyObject, that is not thread-safe, is to be used in some new Java code. Which of the following design decisions can be made to ensure that no race conditions will occur?

a. Provide a static getter for a ThirdPartyObject instance

b. Store instances of ThirdPartyObject in a ThreadLocal.

c. Make any instance of ThirdPartyObject a local (method) variable and ensure that no references to it are published.

d. Use @Immutable as an annotation with ThirdPartyObject instances.

e. Ensure that an instance of ThirdPartyObject is private and can only be accessed using a public getter method

考的是线程安全，问的是：Java SE类ThirdPartyObject，它不是线程安全的，将在一些新的Java中使用代码。以下哪一种设计决策可以确保没有竞争情况会发生。

a. 无论getter 是否静态， 如果这个instance被多个线程同时访问就会竞争

b. 正确

c. 正确， 只在local方法创建对象， 并保证不会被其他方法访问， 这样每个线程都会有自己单独的对象。

d. 不知道什么鬼

e, 单例模式， 如果这个对象是有状态的， 就会发生竞争(线程安全问题）

答案: bc

Q24 🚀

Java EE servlet-based application uses a context attribute that is vital to the operation of the application. Which of the following approaches can be used to ensure thread-safe access to the attribute?

a. Access the attribute within a code block that is synchronized on the request object

b. Agree a strategy where all servlets must access the attribute within a code block that is synchronized on the session object

c. Specify synchronized in the method declarations of doGet and doPost in the servlet

d. Agree a strategy where all servlets must access the attribute within the code block that is synchronized on the context object.

e. Access the attribute within a code block that is synchronized on the session object

考的是synchronized 方法，既然那个是1个 context 属性， 所以我们就必须让context 对象里访问attribute的方法是Synchronized(同步的， 要排队访问的）

答案: d

Q25 🚀

Given code below contains overloaded and overridden constructor. Which of the following can be the result of an attempt to compile and execute this code.

class Superclass {
    Superclass() {
        this(0);
        System.out.println("1");
    }
    Superclass(int x) {
        System.out.println("2" + x);
    }
}
public class Subclass extends Superclass {
    Subclass(int x) {
        System.out.println("3" + x);
    }
    Subclass(int x, int y) {
        this(x);
        System.out.println("4" + x + y);
    }
    public static void main(String[] args) {
        new Subclass(2, 3);
    }
}

a. The output is 32 423

b. The output is. 20 1 32 423

c. The output is 22 32 423

d. The output is 5 9

e. A Recursive constructor invocation compilation error occurs

总结：

1、类加载到内存时static加载

2、调用类的构造方法时先调用父类的构造方法，再调用子类的构造方法

3、类初始化时，先初始化类的属性成员，在执行构造方法

考的是子类如何调用父类构造函数，参考：https://blog.csdn.net/nvd11/article/details/126926028?csdn_share_tail={"type"%3A"blog"%2C"rType"%3A"article"%2C"rId"%3A"126926028"%2C"source"%3A"nvd11"}

重点在Subclass 的双参构造函数中， 因为无显示声明super()， 所以会隐含调用父类的无参构造函数

答案: b

Q26 🚀

In Java the two classes below are declared in the same file:

public class Parent {
    protected static int count = 0;

    public Parent() {
        count++;
    }

    static int getCount() {
        return count;
    }
}
public class Child extends Parent {
    public Child() {
        count++;
    }

    public static void main(String[] args) {
        System.out.println("Count = " + getCount());
        Child obj = new Child();
        System.out.println("Count = " + getCount());
    }
}

Which of the following can be the result of trying to compile and execute this file?

a. The file will compile and run and the output will be : Count = 0 Count = 1

b. The file will not compile

c. The file will compile and run and the output will be : Count = 1 Count = 2

d. The file will compile and run and the output will be : . Count = 0 Count = 2

e. The file will compile but will generate a runtime error

我的想法：同一个文件有两个public类，不能编译，选b

网友答案：d，又是考隐含调用父类无参构造函数， 参考上一题

Q27 🚀

In the Java SE statement shown below, which of the following accurately describe the parameter “MyBundle”?

ResourceBundle bundle = ResourceBundle.getBundle(“MyBundle”, currentLocale);

a. An Internet URL

b. The name of a Java class

c. The name of a command line switch

d. The name-prefix of a series of property files.

e. The name of a .Net dll

accurately：美[ˈækjərətli] adv.准确地;准确地，精确；正确，正确地;

• This bird, sharp of eye and deft of beak, can accurately peck the flying insects in the air.
• 这只鸟眼疾嘴快，能准确地把空中的飞虫啄住。

答案：d，明显参数是配置文件的前序， 考得很偏啊

下面我们来模拟一个多语言的环境

定义四个资源文件：res_en_US.properties、res_zh_CN.properties、res_zh.properties、res.properties

res_en_US.properties：cancelKey=cancel
res_zh_CN.properties：cancelKey=\u53D6\u6D88（取消）
res_zh.properties：cancelKey=\u53D6\u6D88zh（取消zh）
res.properties：cancelKey=\u53D6\u6D88default（取消default）

命名规则按照：资源名+_语言_国别.properties，每个资源文件中定义了本地化的信息，那么系统如何取到对应的资源文件呢？

ResourceBundle bundle = ResourceBundle.getBundle(“res”, new Locale(“zh”, “CN”));

其中new Locale(“zh”, “CN”);这个对象就告诉了程序你的本地化信息，就拿这个来说吧：

程序首先会去classpath下寻找res_zh_CN.properties，若不存在，那么会去找res_zh.properties，若还是不存在，则会去寻找res.properties，要还是找不到的话，那么就该抛异常了：MissingResourceException

我们可以来写个测试程序验证一下：

public static void main(String args[]) {
	ResourceBundle bundle = ResourceBundle.getBundle("res", new Locale("zh", "CN"));
	String cancel = bundle.getString("cancelKey");
	System.out.println(cancel);
	
	bundle = ResourceBundle.getBundle("res", Locale.US);
	cancel = bundle.getString("cancelKey");
	System.out.println(cancel);
	
	bundle = ResourceBundle.getBundle("res", Locale.getDefault());
	cancel = bundle.getString("cancelKey");
	System.out.println(cancel);

	bundle = ResourceBundle.getBundle("res", Locale.GERMAN);
	cancel = bundle.getString("cancelKey");
	System.out.println(cancel);
}

输出：

取消
cancel
取消
取消

Q28 🚀

Which of the following are implementations of the Front Controller pattern for full fledged Spring Web application described by the deployment descriptor below?

<?xml version=”1.0” encoding = “UFT-8”?>
<web-app xmlns = “http://java.sun.com/xml/ns/javaee”
xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
xsi:schemaLocation=”http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd”
version = “2.5”>
    <display-name>Archetype Created Web Application</display-name>
    <servlet>
        <servlet-name> Spring MVC Web Application</servlet-name>
        <servlet-class>
            [Spring Front Controller implementation]
        </servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Spring MVC Web Application</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

a. RequestContextListener

b. RequestContextFilter

c. WebApplicationContext

d. DispatcherServlet

e. ContextLoaderListener

答案：d

implementation: 美[ˌɪmpləmɛnˈteɪʃən] n.实施;执行;

• To study and put forward regulations and rules for anti-smuggling information and organize implementation accordingly.
• 研究提出缉私情报工作规章制度并组织实施。

fledged：美[fledʒd] adj.羽翼已丰的; v.（鸟）长羽毛; fledge（长羽毛）的过去分词和过去式;

• She was now a fully fledged member of the teaching profession.
• 她现在是完全合格的教师。

file descriptor通常被翻译为“文件描述符”,这是计算机科学领域中的一个常见术语。

Q29 🚀

To troubleshoot a problem in a live system, a class is modified slightly resulting in the code shown below:

import java.util.ArrayList;
import java.util.List;
public class IKMProcessor {
    public List<String> queueSequence;
	public void setup()
	{	
		try {
		 	establishQueueSequence();
		} finally {
			cleanupQueueSequence();
			System.out.println(“Queue sequence successfully cleaned up”);
		}
	}
	
	private void cleanupQueueSequence() {
		if (queueSequence.size() > 0) {
			System.out.println(“Queue size > 0”);
		}
	}
	
	private void establishQueueSequence() {
		if (true) {
			throw new IllegalArgumentException();
		}
		queueSequence = new ArrayList<String>();
	}
}

Which of the following can be the result of an attempt to execute the code shown below?

IKMProcessor processor = new IKMProcessor();
processor.setUp();
System.out.println(“Processing complete”);

a. The program runs to completion without exception, but nothing is output

b. The program outputs: Queue sequence successfully cleaned up

c. Processing ends abnormally with an IllegalArgumentException

d. Processing ends abnormally with a NullPointerException .

e. The program outputs: Processing complete

答案:d

考的是Try Catch Exception 处理流程，只不过这里的Exception没有被显式catch.

因为establishQueueSequence throw 出了IllegalArgumentException 异常， 导致queueSequence 没有被初始化，而这个IllegalArgumentException 异常被隐藏地catch了但是没有任何处理，Finally里调用cleanupQueueSequence， 尝试去访问.size()方法， 导致NullPointerException

troubleshoot：美[ˈtrʌblʃuːt] v.故障排除;检修；（为公司、机构等）分析解决（难题）;

• Most of these tools allow you to both quickly troubleshoot a performance problem and capture data for historical trending and analysis.
• 其中的大多数工具都允许您快速地进行故障排除，并获取相关的数据以便进行历史趋势研究和分析。

slightly：美[ˈslaɪtli] adv. 稍微;略微;轻微地;身材瘦小的;

• My arms were aching so I shifted position slightly.
• 我胳膊疼了，所以稍微变了变姿势。

resulting in 美[rɪˈzʌltɪŋ ɪn] 结果是;导致;造成;

• But insurance will be cold comfort following the failure on October 31st of VSS Enterprise, resulting in the death of one pilot and the severe injury to another.
• 但在10月31日企业号太空飞船飞机失事导致一名飞行员死亡,另一名飞行员重伤后,保险只是于事无补的宽慰。

Q30 🚀

Which of the following are valid results of executing the JavaScript code snippet below?

<body onLoad="hi()" onUnload="bye()">
    <script language="javascript">
        var nm = "";
        function hi() {
            nm = prompt("Hello! Your name?", " ");
        }        
        function bye() {
            alert("Goodbye " + nm);
        }        
    </script>
</body>

a. There is no visible output when the document loads

b. After the document loads, a welcome message is displayed and the user is prompted for a name.

c. A syntax error is displayed when function hi() is executed

d. When the user request another URL, a good-bye message is displayed.

e. The document displays and error message, since all functions must be in the

答案：b,d

考的是javascript… 这不是java笔试题吗？

var Hello = new Function(“alert(‘Hello World’);”);

Hello();

上面这种函数定义跟下面是一样的。

function Hello(){ alert(“Hello World”); }

Hello();

另：js是大小写敏感的语言，var a,A;这样的定义两个不同的变量。

Function是一个类的，而function是定义一个函数的关键字

Q31

Which of the following Java Native Interface (JNI) types and keywords map to their machine-dependent Java equivalents?

a. const : constant

b. void : void .

c. jintArray : int []

d. jlong : long.

e. jarray : array

答案： b,d 没写过JNI， 无法解析…

Q33

Which of the following statements correctly describe Hibernate caching? b. Caching dynamic data will improve application performanced. Cached data resides between the application and the database

Q39

In a Java SE environment, garbage collection is causing performance problems and it is suspected Problems are caused by some of the applications making explicit calls to System.gc(). Which of the following JVM Arguments can be used to test this theory? a. –XX:+DisableExplicitGC

Q41

String s = "abcd"; a. The statement s.equals("abcd") will evaluate to true. b. The statement s == "abcd" will evaluate to true c. s.replace('a','f') will modify the string s d. Given String s2 = new String("abcd") The statement s == s2 will evaluate to true e. The statement s = "abcd" will eval Ans: a

Q44

Which of the following statements are valid about JPA Entities in Java EE? a. Mapping between java objects and the related databases must be defined using annotations.d. An entity instance corresponds to a table row.e. An entity is a POJO annotated with the @Entity annotation.

Q59

public class CalendarTest {
    public static void main(String[] args) {
        try {
            Date aDate = new SimpleDateFormat("yyyy-mm-dd").parse("2023-01-03");
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(aDate);
            System.out.println(calendar.get(calendar.DAY_OF_MONTH) + "," + calendar.get(calendar.MONTH));
            int year = calendar.get(Calendar.YEAR);
            int month = calendar.get(Calendar.MONTH)+1; //获取到的月份范围是0-11，所以要+1
            int day = calendar.get(Calendar.DAY_OF_MONTH);
            String tempDate = year + "年" + month + "月" + day + "日";
            System.out.println(tempDate);           
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Q60

1. Which of the following can be result of an attempt to compile and execute the java SE code below?

Q70

A Third Party java application is running out of space on the heap after executing for few hours. Which of the following command line argument can be used at application startup to improve the situation ?

-Xms<size> set initial Java heap size
-Xmx<size> set maximum Java heap size
-Xss<size> set java thread stack size

Q72

Which of the following correctly describe the modules of the Spring architecture? b. The Web module provide transaction management for data access business logic, utilizing AOP to inject transaction logic into domain functionality c. The inversion of Control(IOC) and dependency Injection (DI) contains , as well as fundamental parts of the Spring framework, are provided by the core and Beans modules. d. The transaction modules provides and AOP framework to utilize proxies to transparently inject any desired business logic into domain functionality.

Q73

//错误，传入T的参数给ArrayList，返回的结果也应该是T类型的
List<?> list = new ArrayList<T>();
//因为ArrayList必须是一种类型，得到的也是同一种类型
List<?> list2 = new ArrayList<?>();
//正确
List<T> list3 = new ArrayList<T>();

List<Student> list1 = new ArrayList<>();
list1.add(new Student("张三",18));
//这里如果add(new Teacher(...))就会报错，因为我们已经给List指定了数据类型为Student

//这里我们并没有给List指定具体的数据类型，?泛指可以存放多种类型
List<?> list2 = new ArrayList<>();
list2.add(new Student("李四",20));
list2.add(new Teacher("王五",40));

Q74 🚀

Which of the following are created by the J2SE 5.0 code below?

package pkg;
class Foo {
    native int bar(String S);
    Static {
    	System.loadLibrary(“foo_bar”);
    }
}

a. A native library called foo_bar .

b. A mapping in the registry between the java class Foo and a native application called foo_bar

c. A java class with a native method called bar.

d. A native method called bar, which is used in the native application called foo_bar

e. A static native class called foo_bar

答案: ac

Q75 🚀

A User application deals with late binding in its implementation as is shown in the Java SE code snippet

class LB_1 {
    public void retValue() {
        System.out.println("LB_1");
    }
    pubicl class LB_2 extends LB_1 {
        public void retValue() {
        	System.out.println("LB_2");
        }
        public static void main(String args[]) {
            LB_1 lb = new LB_2();
            lb.retValue();
        }
	}
}

a. A runtime error will occur

b. A compilation error will occur

c. LB_2

d. LB_1 LB_2

e. LB_1

答案：c

重写送分题，无需解析

Q76 🚀

Which of the following correctly describe the output from the Java SE program below?

import java.text.ParseException;
import java.text.SImpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class CalendarTest {
    public static void main(String[] args) {
        Date aDate = null;
        try {
            aDate = new SimpleDateFormat("yyyy-mm-dd").parse("2012-01-15");
            Calendar aCalendar = Calendar.getInstance();
            aCalendar.setTime(aDate);
            System.out.print(aCalendar.get(aCalendar.DAY_OF_MONTH) + "," + aCalendar.get(aCalendar.MONTH));
        } catch (ParseException ex) {
            System.out.println(ex);
        }
    }
}

a. java.text.ParseException : unparseable date: “2012-01-15”

b. 1,0

c. 15,1

d. 1,1

e. 15,0

答案：e

Calendar.MONTH 从零开始，不是C， 智商不行了

Q77 🚀

Which of the following can be result of an attempt to compile and execute the java SE code below?

import java.math.BigDecimal;
interface Account{
	BigDecimal balance = new BigDecimal(0.0);
}
class SavingAccount implements Account{
	public SavingAccount(BigDecimal intialValue){
		balance = intialValue;
	}
	public String toString(){
		return balance.toString();
	}
}
public	class Test25 {
    public	static	void main(String[] args) {
        SavingAccount instance= newSavingAccount(new BigDecimal(50.00));
        System.out.println(instance);
    }
}

A. Class SavingAccount is the output

B. 0.00 is output

C. A compilation error occurs.

D. A runtime exception is thrown

E. 50.00 is the output.

答案: C

考的是接口， 其实接口的成员都是public static final的，而方法都是 public abstract的。

Q78 🚀

Which of the following statements are correct about the java.util.Queue<E> interface in Java SE?

a. The Queue class has 2 constructors, a zero argument constructor and a constructor that takes an int param(capacity)

b. A Queue object orders its elements in a FIFO (First In First Out) manner

c. In a PriorityQueue<Integer>, a call to element is guaranteed to return the element with the highest integer value

d. In a Queue object containing one or more elements, the element and remove methods both return the same element. In a BlockingQueue<E>, a call to put is guaranteed to block unless the queue is full

答案：bd

注意的是Queue是接口

manner: 美[ˈmænər] n.方式;方法;态度;举止;礼貌;礼仪;规矩;

• The manner in which the decision was announced was extremely regrettable.
• 宣布决定的方式非常令人遗憾。

"in which" 是一个用于引导定语从句的短语，通常用于修饰先行词，进一步说明先行词的性质或特征。以下是 "in which" 的一些常见用法及例句：

1. 用于表示位置或方位：

• The house, in which I was born, has been demolished.（我出生的那座房子已经被拆毁了。）

• He pointed to the building in which the meeting would be held.（他指着将要举办会议的那座楼。）

2. 用于表示时间：

• This is the decade in which he made his fortune.（这是他发财的十年。）

• The period in which the company grew rapidly was marked by innovation.（创新是公司快速增长的时期的标志。）

3. 用于描述条件或情况：

• I will only accept the job offer under the conditions in which I have the freedom to work remotely.（只有在我有远程工作自由的条件下，我才会接受这份工作。）

• The circumstances in which the decision was made were very difficult.（在那种情况下作出这个决定很困难。）

4. 用于说明方式或特点：

• She described the way in which she solved the problem.（她描述了解决问题的方法。）

• The process in which the product is manufactured is highly efficient.（产品制造的流程非常高效。）

这些例句展示了 "in which" 在不同情境下的不同用法，包括表示位置、时间、条件、方式等。

Q79 🚀

Which of the statement accurately describe a checked exception in Java SE?

A. A subclasses of java.lang.Throwable annotated with @checked

B. A class that implements java.lang.CheckedException

C. A subclass of java.lang.RuntimeException

D. A subclass of java.lang.CheckedException

E. A subclass of java.lang.Exception.

答案：E

Checked exception: 继承自 Exception 类。代码需要处理 API 抛出的 checked exception，要么用 catch 语句，要么直接用 throws 语句抛出去。

Unchecked exception: 也称 RuntimeException，它也是继承自 Exception。但所有 RuntimeException 的子类都有个特点，就是代码不需要处理它们的异常也能通过编译，所以它们称作 unchecked exception。RuntimeException（运行时异常）不需要强制try…catch…或throws 机制去处理的异常。我今天才知道RuntimeException 还有另1个名字 unchecked exception。

A, Throwable 明显是接口

B. 没有CheckedException这玩意

C. 相反

D. 没有CheckedException这玩意

E, 正确

accurately： 美[ˈækjərətli] adv. 准确地;准确地，精确；正确，正确地;

• This bird, sharp of eye and deft of beak, can accurately peck the flying insects in the air.
• 这只鸟眼疾嘴快，能准确地把空中的飞虫啄住。

Q80 🚀

In Java SE which of the following statement are true about RandomAccessFile class define in java.io package?

A. The valid RandomAccessFile modes are r, w, and rw

B. When a RandomAccessFile is created in write only mode it always write bytes starting at the file pointer

C. A RandomAccessFile object can be instantiated in read only mode.

D. If an existing file is flagged as read only on the file system then the RandomAccessFile constructor can throw an “access is denied” exception

E. The RandomAccessFile has a method that returns the offset at which the next read or write will take place.

答案：CE

A，支持 r 和rw模式， 还没见只写模式的~

B. 同上

C. 正确

D. 可以用r模式打开

E. RandomAccessFile有一个方法，它返回下一次读或写的偏移量（开始位置）。正确

long getFilePoint():设置文件指针偏移，从该文件的开头测量，发生下一次读取或写入。(前面是文档原文翻译通俗一点就是：返回文件记录指针的当前位置,不指定指针的位置默认是0。)

void seek(long pos):设置文件指针偏移，从该文件的开头测量，发生下一次读取或写入。（前面是文档原文翻译通俗一点就是：将文件记录指针定位到pos位置。）

RandomAccessFile类的实例支持对随机访问文件的读取和写入。随机访问文件的行为类似存储在文件系统中的一个大型 byte 数组。存在指向该隐含数组的光标或索引，称为文件指针；输入操作从文件指针开始读取字节，并随着对字节的读取而前移此文件指针。如果随机访问文件以读取/写入模式创建，则输出操作也可用；输出操作从文件指针开始写入字节，并随着对字节的写入而前移此文件指针。写入隐含数组的当前末尾之后的输出操作导致该数组扩展。该文件指针可以通过 getFilePointer 方法读取，并通过 seek 方法设置。

Q81 🚀

package com.ikm
class A{
	public void m1(){
		System.out.println(“A.m1, ”);
	}
	protected void m2(){
		System.out.println(“A.m2, ");
	}
	private void m3(){
		System.out.println(“A.m3, ”);
	}
	void m4(){
		System.out.println(“A.m4, ”);
	}
}
public class B{
	public static void main(String [] args){
		A a = new A();
		a.m1();
		a.m2();
		a.m3();
		a.m4();
	}
}

A. The line a.m4(); causes compilation error.

B. The program outputs:A.m1, Am2,Am3,Am4.

C. The line a.m3(); causes compilation error.

D. The line a.m1(); causes compilation error.

E. The line a.m2(); causes compilation error.

	类内部	本包	子类	外部包
public	YES	YES	YES	YES
protect	YES	YES	YES	NO
default	YES	YES	NO	NO
private	YES	NO	NO	NO

答案：C

compilation: 美[ˌkɑːmpɪˈleɪʃn] 编译