高级研发工程师(偏数据库方面)

脉展软件技术有限公司2011Q2招聘-高级研发工程师笔试题基础测试题卷面上不能出现任何的涂写文字，所有的答案要求写在答题纸上，考卷不得带走。

选择题1、What will happen when you attempt to compile and run the following code? （3）public class Static {static {int x = 5; // 在static内有效}static int x, y; // 初始化为0public static void main(String args[]) {x--; // -1myMethod();System.out.println(x + y + ++x);}public static void myMethod() {y = x++ + ++x; // y=-1+1 x=1}}A. compiletime errorB. prints: 1C. prints: 2D、 prints: 3E、prints: 7F、prints: 82、Given the following code, what will be the output? （3）class Value {public int i = 15;}public class Test {public static void main(String argv[]) {Test t = new Test();t.first();}public void first() {int i = 5;Value v = new V alue();v.i = 25;second(v, i);System.out.println(v.i);}public void second(Value v, int i) {i = 0;v.i = 20;Value val = new Value();v = val;System.out.println(v.i + " " + i);}}A、 15 0 20B、 15 0 15C、 20 0 20D、 0 15 203、What will happen when you attempt to compile and run the following code? （3）class MyParent {int x, y;MyParent(int x, int y) {this.x = x;this.y = y;}public int addMe(int x, int y) {return this.x + x + y + this.y;}public int addMe(MyParent myPar) {return addMe(myPar.x, myPar.y);}}class MyChild extends MyParent {int z;MyChild(int x, int y, int z) {super(x, y);this.z = z;}public int addMe(int x, int y, int z) {return this.x + x + this.y + y + this.z + z;}public int addMe(MyChild myChi) {return addMe(myChi.x, myChi.y, myChi.z);}public int addMe(int x, int y) {return this.x + x + this.y + y;}}public class MySomeOne {public static void main(String args[]) {MyChild myChi = new MyChild(10, 20, 30);MyParent myPar = new MyParent(10, 20);int x = myChi.addMe(10, 20, 30);int y = myChi.addMe(myChi);int z = myPar.addMe(myPar);System.out.println(x + y + z);}}A、 300B、 240C、 120D、 180E、compile errorF、none of the above4、What will happen when you attempt to compile and run the following code? （3）interface MyInterface {}public class MyInstanceTest implements MyInterface {static String s;public static void main(String args[]) {MyInstanceTest t = new MyInstanceTest();if (t instanceof MyInterface) {System.out.println("I am true interface");} else {System.out.println("I am false interface");}if (s instanceof String) {System.out.println("I am true String");} else {System.out.println("I am false String");}}}A、 compile time errorB、 runtime errorC、 prints: “I am true interface”followed by “I am true String”D、 prints: “I am false interface”followed by “I am false String”E、prints: “I am true interface”followed by “I am false String”F、prints: “I am false interface”followed by “I am true String”5、What results from attempting to compile and run the following code? （3）public class Ternary {public static void main(String args[]) {int a = 5;System.out.println("Value is - " + ((a < 5) ? 9.0 : 9)); ? 数据类型的自动转换}}A、 print:Value is -9B、 print:Value is -5C、 Compilation errorD、None of these6、What will be the result of executing the following code? （3）public static void main(String args[]) {char digit = 'a';for (int i = 0; i < 10; i++) {switch (digit) {case 'x': {int j = 0;System.out.println(j);}default: {int j = 100;System.out.println(j);}}}int i = j;System.out.println(i);}A、 100 will be printed 11 times.B、 100 will be printed 10 times and then there will be a runtime exceptionC、 The code will not compile because the variable i cannot be declared twice within the mani() method.D、 The code will not compile because the variable j cannot be declared twice within the switch statement.E、None of these.7、Which of the following collection classes from java.util package are Thread safe? （3）A、 VectorB、 ArrayListC、 HashMapD、 Hashtable8、What will happen when you attempt to compile and run the following code? （3）class MyThread extends Thread {public void run() {System.out.println("MyThread: run()");}public void start() {System.out.println("MyThread: start()");}}class MyRunnable implements Runnable {public void run() {System.out.println("MyRunnable: run()");}public void start() {System.out.println("MyRunnable: start()");}}public class MyTest {public static void main(String args[]) {MyThread myThread = new MyThread();MyRunnable myRunnable = new MyRunnable();Thread thread = new Thread(myRunnable);myThread.start();thread.start();}}A、 prints: MyThread: start() followed by MyRunnable: run()B、 prints: MyThread: run() followed by MyRunnable: start()C、 prints: MyThread: start() followed by MyRunnable: start()D、 prints: MyThread: run() followed by MyRunnable: run()E、compile time errorF、None of the above9、Which of the following will output -4.0?（3）1、System.out.println(Math.floor(-4.7));2、System.out.println(Math.round(-4.7));3、System.out.println(Math.ceil(-4.7));4、System.out.println(Math.min(-4.7));10、What will happen if you attempt to compile and run the following code?（3）Integer ten=new Integer(10);Long nine=new Long (9);System.out.println(ten + nine);int i=1;System.out.println(i + ten);1、19 followed by 202、19 followed by 113、Error: Can’t convert java lang Integer4、10 followed by 1问答题1、请写出Java中的数据类型划分及默认值。