Java基础测试试题.doc

Java基础测试试题一、代码查错（每题4分，共计32分）1abstract class Name private String name; public abstract boolean isStupidName(String name) /抽象类里面不能有实现的方法，去掉2public class Something void doSomething () private String s = ;/去掉修饰的private，方法中的变量不能被修饰服修饰 int l = s.length(); 3abstract class Something private abstract String doSomething ();去掉private,用abstract修饰的类中的方法是要被实现的，不能用private修饰，可以用protecte d修饰4public class Something public int addOne(final int x) return +x; 去掉修饰词final5class Something final int i; public void doSomething() System.out.println(i = + i); /I没有初始化6public class Something public static void main(String args) Something s = new Something(); System.out.println(s.doSomething() returns + doSomething();/这里的方法要是静态的方法，也可以这样s.doSomething调用 public String doSomething() return Do something .; 7interface A int x = 0;class B int x =1;class C extends B implements A public void pX() System.out.println(x); public static void main(String args) new C().pX(); 8interface Playable void play();interface Bounceable void play();interface Rollable extends Playable, Bounceable Ball ball = new Ball(PingPang);class Ball implements Rollable private String name; public String getName() return name; public Ball(String name) = name; public void play() ball = new Ball(Football); System.out.println(ball.getName(); 二、问答题（每题8分，共计32分）1Java线程的实现方式有哪两种？线程又有哪四种状态？分别说明class Object和class Thread下有哪些常用的线程函数？实现线程同步的优化方式是什么？ 2运行时异常（runtime exception）与一般异常有何异同？error和exception又有什么区别？3GC是什么？ 为什么要有GC？java中会存在内存泄漏吗？4请写出四种以上常用设计模式？三、程序输出结果题（每题6分，共计18分）1Class APublic static viod main(String args)trySystem.out.println(hello);throw new Exception();catch(Exception e)System.out.println(world);System.exit(0);finallySystem.out.println(!);2public class Test2 public static void main (String args) StringBuffer a = new StringBuffer (A); StringBuffer b = new StringBuffer (B); operate (a,b); System.out.println(a+,+b); static void operate(StringBuffer x, StringBuffer y) x.append(y); y = x; 3public class Test2 public static void add3 (Integer i) int val=Value(); val += 3; i = new Integer (val); public static void main (String args ) Integer i = new Integer (0); add3 (i);