}
5. class Something { int i;
public void doSomething() { System.out.println(\} }
二、下面代码编译和运行的结果是什么？ 1. 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 Value(); 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 + \} }
A.15 0 20 B.15 0 15 C.20 0 20 D.0 15 20 2. class FatherClass { public FatherClass(){
System.out.println(\} }
public class ChildClass extends FatherClass{ public ChildClass() {
System.out.println(\}
public static void main(String[] args) {
FatherClass fc = new FatherClass();
ChildClass cc = new ChildClass(); } }
3. public class Static{ static{ int x = 5; }
static int x,y;
public static void main(String args[]){ x--;
myMethod();
System.out.println(x + y + ++x); }
public static void myMethod(){ y = x++ + ++x; } }
A.编译错误 B.输出１ C.输出２ D.输出３ 4. 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.300 B.240 C.120 D.180 答案：
一、1. 错。abstract method必须以分号结尾，且不带花括号。
2. 错。abstract的methods不能以private修饰。abstract的methods就是让子类implement(实现)具体细节。
3. 错。int x被修饰成final，意味着x不能在addOne method中被修改。
4. 正确。在addOne method中，参数o被修饰成final。如果在addOne method里我们修改了o的reference(比如: o = new Other();)，那么如同上例
这题也是错的。但这里修改的是o的member vairable(成员变量)，而o的reference并没有改变。
5. 正确。输出的是\。 二、1. 正确答案A 2. 答案：
FatherClass Create FatherClass Create ChildClass Create 3. 正确答案 D 4. 正确答案：A
第八单元 试题 一、判断程序段 1. class Something { final int i;
public void doSomething() { System.out.println(\} }
7. interface Playable { void play(); }
interface Bounceable { void play(); }
interface Rollable extends Playable, Bounceable { Ball ball = new Ball(\}
class Ball implements Rollable { private String name;
public String getName() { return name; }
public Ball(String name) { this.name = name; }
public void play() {
ball = new Ball(\
System.out.println(ball.getName()); } }
二、下面代码编译和运行的结果是什么？ 1. class MyThread extends Thread{ public void run(){
System.out.println(\}
public void start(){
System.out.println(\} }
class MyRunnable implements Runnable{ public void run(){
System.out.println(\}
public void start(){
System.out.println(\} }
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.打印MyThread: start() 后面跟 MyRunnable: run() B.打印MyThread: run() 后面跟MyRunnable: start() C.打印MyThread: start() 后面跟MyRunnable: start() D.打印MyThread: run() 后面跟MyRunnable: run() 2. // 文件名：SuperclassX.java package packageX;
public class SuperclassX{
protected void superclassMethodX(){} int superclassVarX; }
//文件名：SubclassY.java
1.package packageX.packageY; 2.
3.public class SubclassY extends SuperclassX 4.{
5. SuperclassX objX = new SubclassY(); 6. SubclassY objY = new SubclassY(); 7. void subclassMethodY() 8. {
9. objY.superclassMethodX(); 10. int i;
11. i = objY.superclassVarX; 12. } 13.}
A.第5行编译错 B.第9行编译错 C.第11行意外 D.都不是 3. 程序段如下： 1.class MyClass 2.{
3. void myMethod(int i) {System.out.println(\
4. void myMethod(String s) {System.out.println(\5. public static void main(String args[]) 6. {
7. MyClass obj = new MyClass(); 8. char ch = 'c';
9. obj.myMethod(ch); 10. } 11.}
A.第四行编译出错 B.第九行抛出例外
C.输出结果：int version D.输出结果：String version 4. public class ThrowsDemo { static void throwMethod() {
System.out.println(\