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Incorrect Java

(2024-01-25 03:11:53) 下一個
1.
 
public static String removeBlankAndDot(String target) {
    if (target != null) {
       StringBuffer buf = new StringBuffer();
       for (int ii=0;ii<target.length();ii++) {
          char c = target.charAt(ii);
          if (c != ' ' && c != '.') buf.append(c);
       }
       return buf.toString();
    }
    return null;
}
 
2.
 
public class DataLogger {
    private static PrintStream err = System.err;
    private static String filePath = "log";
    private static String fileName = "my.data";
    private static PrintWriter log;
 
    public static void logData(String logInfo) {
    try {
       if (log == null) {
   File file = new File(filePath + System.getProperty("file.separator") + fileName);
   log = new PrintWriter(new FileOutputStream(file));
       }
       if (!logInfo.equals("")) {
         log.println(logInfo);
         log.flush();
       }
    }
    catch (Exception e) {
       e.printStackTrace(err);
       System.exit(1);
    }
}
 
3.
 
public class Hello {
  public static void main(String[] args) {
     String name = "John";
     char[] numbers = { '1', '0' };
     System.out.println(name + " is the number " + numbers);
  }
}
 
4.
 
public class Hello {
  public static void main(String[] args) {
     Date d1 = new Date("1 Apr 98");
     nextDateUpdate(d1);
     System.out.println("NextDay: " + d1);
  }
  private static void nextDateUpdate(Date arg) {
     arg = new Date(arg.getYear(), arg.getMonth(), arg.getDate() + 1);
  }
}
 
5.
 
// double values[100] initialized here
 
double getValueForPeriod(int periodNumber) {
   try {
       return values[periodNumber];
   } catch (ArrayIndexOutOfBoundException e) {
       return 0.0;
   }
}
 
6.
 
static void copy(String src, String dest) throws IOException {
  InputStream in = null;
  OutputStream out = null;
  try {
    in = new FileInputStream(src);
    out = new FileOutputStream(dest);
    byte[] buf = new byte[1024];
    int n;
    while ((n = in.read(buf)) >= 0) {
       out.write(buf, 0, n);
    }
  } finally {
    if (in != null) in.close();
    if (out != null) out.close();
  }
}
 
7.
 
public class Timer {
  public static final Timer INSTANCE = new Timer();
  private final int diffTime;
  private static final int CURRENT_YEAR =
    Calendar.getInstance().get(Calendar.YEAR);
 
  private Timer() {
    diffTime = CURRENT_YEAR - 1949;
  }
  public int diffTime() {
    return diffTime;
  }
  public static void main(String[] args) {
    System.out.println("diff Time is " + INSTANCE.diffTime());
  }
}
 
8.
 
public String getStrTrim () {
  String string = new String("  14 units  ");
  string.trim();
  return string;
}
 
9.
 
public class PingPong {
  public static synchronized void main(String[] a) {
    Thread t = new Thread() {
      public void run() { pong(); }
    };
    t.run();
    System.out.print("Ping");
  }
  static synchronized void pong() {
    System.out.print("Pong");
  }
}
 
10.
 
public class Stack {
  private Object[] elements;
  private int size = 0;
  public Stack(int initialCapacity) {
    this.elements = new Object[initialCapacity];
  }
  public void push(Object e) {
    ensureCapacity();
    elements[size++] = e;
  }
  public Object pop() {
    if (size == 0) throw new EmptyStackException();
    return elements[--size];
  }
}
 
11.
 
public boolean isYourTime(Date d) {
     Date d1 = new Date("1 Apr 98");
     Date d2 = new Date("1 Apr 99");
     return d.compareTo(d1) >= 0 &&
            d.compareTo(d2) < 0;
}
 
12.
 
public final class Period {
  private final Date start;
  private final Date end;
  public Period(Date start, Date end) {
    this.start = start;
    this.end = end;
    // verify start >= end
  }
  public Date getStart() {
    return start;
  }
}
 
13.
 
publish Hashtable test(Hashtable ht) {
// ...
  Hashtable newHt = new Hashtable();
// ...
  return newHt;
}
 
14.
 
public abstract class A {
 
  public abstract void process();
}
 
public class DB extends A {
 
  public void process() {
   // retrieve data from database 
  }
}
 
public class SAX extends A {
 
  public void process() {
   // processing the data from SAXparser 
  }
}
 
15.
 
private List cheesesInStock = ...
 
public Cheese[] getCheeses() {
  if (cheesesInStock.size() == 0) {
     return null;
  }
}
 
16.
 
public abstract class WorkQueue {
  private final List queue = new LinkedList();
  protected WorkQueue() { new WorkerThread().start(); }
  public final void enqueue(Object workItem) {
    synchronized(queue) {
       queue.add(workItem);
       queue.notify();
    }
  }
  protected abstract void processItem(Object workItem) 
     throws InterruptedException;
  private class WorkerThread extends Thread {
     public void run() {
        while (true) {
           synchronized(queue) {
             // ...
             Object workItem = queue.remove(0);
             try {
                processItem(workItem);
             } catch (InterruptedException e) {
                return;
             }
           }
        }
     }
  }
}
class UseQueue extends WorkQueue {
   protected void processItem(Object workItem)
     throws InterruptedException {
       Thread child = new Thread() {
         public void run() { enqueue(workItem); }
       };
       child.start();
       child.join();
   }
}
 
17.
 
public abstract class Asset {
  abstract protected powerDown();
 // ...
}
 
public class ComputerAsset extends Asset {
// ...
 protected void powerDown() {
 }
}
 
public class ComputerServer extends ComputerAsset {
// ...
 public powerDown() {
  // empty
 }
}
 
public class BuildingAsset extends Asset {
// ...
 protected void powerDown() {
 }
}
 
public class BuildingLight extends BuildingAsset {
// ...
 protected void powerDown() {
 }
}
 
public class EmergencyLight extends BuildingLight {
// ...
 public powerDown() {
  // empty
 }
}
 
public class ComputerMonitor extends ComputerAsset {
// ...
 public powerDown() {
  // need do something
 }
}
 
public class RoomLights extends BuildingLight {
// ...
  public powerDown() {
  // need do something
 }
}  
 
public class BuildingManagement {
  Asset things[] = new Asset[24];
  int numItems = 0;
  public void goodNight() {
    for (int i = 0; i < things.length; i++) {       
       things[i].powerDown();
    }
  }
  public void add(Asset thing) {
    // ...
  }
}
 
public static void main(String[] args) {
  BuildingManagement b1 = new BuildingManagement();
  b1.add(new RoomLights(101));
  b1.add(new EmergencyLight(100));
  // ...
  b1.add(new ComputerMonitor(200));
  b1.goodNight();
}
 
18.
 
public int loadData(Connection conn, String sql) throws SQLException {
  // ...
  ResultSet rs = null;
  Object[] record = null;
  this.data = new ArrayList();
  try {
  // ...
    while (rs.next()) {
      record = new Object[columnCount];
      for (int i = 0; i < columnCount; i++) {
        record[i] = rs.getObject(i);
      }
      data.add(record);
    }
  } finally {
   // ...
  }
}
 
19.
 
public void printMetaData(Connection conn) {
  // ...
  DatabaseMetaData dmd = conn.getMetaData();
  ResultSet rs = dmd.getTable(null,null,null,tabletypes);
  while (rs.next()) {
     // ...
     String table = rs.getString("TABLE_NAME");
     ResultSet rs2 = dmd.getColumns(null,null,table,null);
     while (rs2.next()) {
       // ...
     }
     rs2.close();
  }
  rs.close();
}
 
20.
 
public void add1000(Vector v, String s) {
  for (int i = 0; i < 1000; i++) {
    v.add(s);
  }
}
 
21.
 
public void test() {
  // ...
  Hashtable ht = new Hashtable();
  ...
  if (!ht.containsKey(key)) {
    return ht.get(key);
  }
  if (!ht.containsKey(key)) {
    ht.put(key, value);
  }
}
 
22.
 
String s = "info";
String p = null;
public void func() {
  Vector v = new Vector();
  v.addElement(s);
// ...
  p = (String) v.elementAt(0);
  Vector v1 = new Vector();
// do other thing
}
 
23.
 
BufferedWriter fw = 
  new BufferedWriter(
    new FileWriter("stock.dat"));
 
String s = buy.toString();
fw.write(s, ...);
 
24.
 
public void callManyTimes() {
  for (Iterator i = myList.iterator(); i.hasNext();)
  {
    Node node = (Node) i.next();
    // ...
  }
 
25.
 
Map first = new ...
Map second = new ...
boolean isSubmap = true;
for (Iterator i = sencond.keySet().iterator(); i.hasNext();) {
  Object key = i.next();
  Object valueInFirst = first.get(key);
  Object valueInSecond = second.get(key);
  if (valueInSecond == null) {
    if (valueInFirst != null) {
     // ...
    }
  } else if (!valueInSecond.equals(valueInFirst)) {
    // ...
  }
}
 
26.
 
public class test {
  public static void main(String[] args) {
    // ...
    try{
      Connection con = DriveManager. ...
      new TablePrinter(con, "Names").walk();
    } catch (SQLException e) {
      // ...
    }
  }
}
 
abstract class TableWalker {
  Connection con;
  String tableName;
  public TableWalker(Connection c, String tablename) {
   this.con = c;
   // ...
  }
 
 public void walk() throw SQLException {
  // ...
  ResultSet rs = stm.executeQuery(queryString);
  while(rs.next()) {
    execute(rs);
  }
  con.close();  // this is wrong place to stay
 }
 public abstract void execute(ResultSet rs) throws SQLException;
}
 
public class TablePrinter extends TableWalker {
  public TablePrinter(Connection c, String tablename) {
    super(c, tablename);
  }
  public void execute(ResultSet rs) throws SQLException {
   // ...
  }
}
 
27.
 
public class Work {
  private Hashtable ht = new Hashtable();
  // ...
  public final void enHt(Object key, Object value) {
    synchronized(ht) {
       ht.put(key, value);
    }
  }
}
 
28.
public class A {
    private static String fileName = "myfile.txt";
    ...
    public FileOutputStream writer = new FileOutputStream(fileName);
 
    public void write(int b) throws IOException {
       writer.write((byte)b);
    }
    ...
}
 
29.
public ManyMethodsCallThisFun () {
...
  for (int i = 0; i < size; i++) {
      Map<String, Record> map =
        Collections.synchronizedMap(
            new HashMap<String, Record>(states[i]);
        db.add(states[i], map);
   }
...
}
 
30.
 
public class A {
 
  public static void main (String[] args) {
      
     C c = new C();
     c = null;
     System.gc();
  }
 
  class C implements aListener {
 
     private D d = null;
     public C() {
         d = D.getInstance();
         d.addaListener(this);
     }
     ...
  }
  class D { // D is Singleton
     ...
 
    public void removeaListener(aListener a) {
     ...
    }
  }
}
 
31.
 
String x = "Hello ";
   x += name;
 
32.
 
private Node getNode(String key, Map map) {
 
  Nodekey nodekey = new Nodekey(key);
  Node n = (Node) map.get(nodekey);
  ...
  return n
}
 
33.
 
public class A {
  private String name = "foo";
  ...
 
  public A() {
    setName("foo");
    ...
  }
  public void setName(String s) {
     this.name = s;
  }
  ...
}
 
34.
 
public void readName() throws IOException {
   
   name = in.read();
 
}
 
35.
 
interface Info {
 
  int PINK = 1;
  int BLUE = 2;
  ...
}
 
public class Graph implements Info {
 
  ...
  switch (color) {
     case PINK:
     ...
  }
}
 
36.
 
public void func(String str) {
  
  Runnable r = new Runnable() {
 
      public void run() {
 
        System.out.println(str);
 
      }
  };
  Thread t = new Thread(r);
  t.start();
}
 
37.
 
public class FileCopier {
 
   public FileCopier(String source, String dest) throws FileCopierEx {
 
     // catch IOException and throw FileCopierEx
 
   }
}
 
try {
  
  FileCopier fc = new filecopier(s, d);
 
} catch (FilecopierEx fce) {
 
  ...
}
fc.docopy();
 
38.
 
BufferedOutputStream fos = 
  new BufferedOutputStream(
    new FileOutputStream("stock.dat"));
 
    fos.write(buy.toBytes());
    fos.flush();
    fos.write(sell.toBytes());
    fos.flush();
 
39.
 
if (s.startWith("a")) {...}
 
if (s.startWith("cd")) {...}
 
40.
 
try { 
   ...
   System.out.write(somethings);
} catch (IOException e) {...}
 
41.
 
public class A {
 
   public static void main(String[] args) {
 
      ...
      StringBuffer word = null;
      switch(item) {
        case 1:
          word = new StringBuffer('M');
          break;
          ...
      }
      word.append('e');
      ...
   }
}
 
42.  EJB2  JNDI
 
Object obj = context.lookup("java:comp/env/AccountHome");
 
43.  EJB2
 
public class Mysession implements SessionBean {
 
    SessionContext ctx;
 
    ...
    public Myfuc() throws mysessionException {
      try {
       withdraw(...);
       deposit(...);
      } catch (mysessionException e) {
        throw e;
      }
    }
    ...
}
 
 
 
 
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