读代码分析结果

读代码分析结果答案在最后，先做再看！

阅读代码段，看是否有错，如果有错。请写出并改正！如果没有，写出结果！

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一、

public class ExceptionTest {    public static void main(String[] args) {        try {            String str = null;            System.out.println(str.length());        } catch (NullPointerException e) {            System.out.println("a");        } catch (RuntimeException e) {            System.out.println("b");        } finally {            System.out.println("c");        }    }}

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二、

public class Forest implements Serializable {    private Tree tree = new Tree();    public static void main(String[] args) {        Forest f = new Forest();        try {            FileOutputStream fs = new FileOutputStream("forest.set");            ObjectOutputStream os = new ObjectOutputStream(fs);            os.writeObject(f);            os.close();        } catch (Exception e) {            e.printStackTrace();        }    }    class Tree {        ;    };}

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三、

public class Hello {    String title;// null    int value;// 0    public Hello() {        title = "World";    }    public Hello(int value) {        this.value = value;        title = "Hello";        Hello();    }    public static void main(String[] args) {        Hello h = new Hello();        System.out.println(h.title);    }}

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四、

public class IfTest {    interface DeclareStuff {        public static final int SKEY = 3;        void doStuff(int x);    }    public class TestDeclare implements DeclareStuff {        public void doStuff(int x) {            x += SKEY + ++x;            System.out.println(x);        }    }    public static void main(String[] args) {        int x = 5;        new IfTest().new TestDeclare().doStuff(++x);//6    }}

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五、

public class ThreadTest implements Runnable {    public static void main(String[] args) throws Exception {        Thread t = new Thread(new ThreadTest());        t.start();        System.out.println("Start");        t.join(1000);        System.out.println("Compliete");    }    public void run() {        for (int i = 0; i < 4; i++) {            System.out.println(i);        }    }}

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六、

public class TimerTest {    public static void appendList(List list) {        list.add("test");    }    public static void main(String[] args) {        List<Integer> aalist = new ArrayList<Integer>();        aalist.add(11);        appendList(aalist);        System.out.println(aalist.get(1));    }}

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• 第一题：
  a
  c

• 第二题：
  报错 java.io.NotSerializableException: com.test.offer.Forest$Tree
  因为：一个可序列化的类，必须要求他的变量也是可序列化的，要是变量不能被序列化那这个类就不能被序列化

• 第三题：
  World

• 第四题：
  16

• 第五题：
  Start
  0
  1
  2
  3
  Compliete

• 第六题：
  test