[2] Page xvi

In the seventh line from the bottom, change "bugs fixes" to "bug fixes".

[6] Page 18

Change "You can download them from http://www.phptr.com/corejava." to "You can download them from http://horstmann.com/corejava."

[4] Page 25

In the NOTE, change "Environnment" to "Environment".

[6] Page 36

Change “it simply displays the string We will not use 'Hello, World'!” to “it simply displays the string We will not use 'Hello, World!'” (i.e. move the ! inside the quotes to match the program at the top of the page)

[5] Page 40

After "..you use a p, not an e, to denote the exponent." add: "The exponent is specified in decimal and denotes a power of two."

[4] Page 41

Change "an unused 2048 byte-range" to "a range of 2048 unused values"

[6] Page 56

Change "Point your web browser to the docs/api/index.html subdirectory of your JDK installation." to "Point your web browser to the index.html file in the docs/api subdirectory of your JDK installation."

[6] Page 62, 123, 125, 465, 629, 630, 631, 640, 641, 642, 649, 681,

Change "Boolean" to "boolean" (in monospace)

[5] Page 62

Remove the line "^ Converts to upper case 0XCAFE". (This option was present in the Java 5 release candidate, but it was later dropped.)

[6] Page 63

Change "You use two a two-letter format..." to "You use a two-letter format..."

[4] Page 64

Last line of Table 3-7 (continued): Change E to Q.

[2] Page 80 BigIntegerTest.java line 8

Change Scanner.create to new Scanner

[4] Page 85

Change System.out.print(" " + a[i]); to System.out.print(" " + args[i]);

[4] Page 86

Change "Initially that is just r itself, but ..." to "Initially that is just r + 1, but..."

[4] Page 89 CompoundInterest.java line 5

Change final int STARTRATE to final double STARTRATE

[6] Page 95

Change "Encapsulation (sometimes called data hiding) is a key concept in working with objects. Formally, encapsulation is nothing more than combining data and behavior in one package and hiding the implementation of the data from the user of the object." to "Encapsulation (sometimes called information hiding) is a key concept in working with objects. Formally, encapsulation is nothing more than combining data and behavior in one package and hiding the implementation details from the user of the object."

[4] Page 95

Change "When you invoke a message on an object" to "When you invoke a method on an object"

[6] Page 96

Change "Thus, a class depends on another class if its methods manipulate objects of that class." to "Thus, a class depends on another class if its methods use or manipulate objects of that class."

[4] Page 104-106 CalendarTest.java

The program prints an unsatisfactory calendar in locales whose first day of the week is not Sunday. (In most parts of the world, the first day of the week is considered Monday--after all, Saturday and Sunday are the weekend.) The following changes take care of this:

• Remove the header SunMon Tue Wed Thu Fri Sat on page 104
• In the program listing, replace lines 18 and 19 with
  

   // get first day of week (Sunday in the U.S.)
   int firstDayOfWeek = d.getFirstDayOfWeek();

• In lines 22 and 49, replace Calendar.SUNDAY with firstDayOfWeek
• Add the following four lines before the } in line 44. (The first line is blank)
  

  
   // start a new line at the start of the week
   if (weekday == firstDayOfWeek)
   System.out.println();
  

• Remove lines 36 through 39

[4] Page 105

Change "For each day, we print a space if the day is < 10, then the day, and then a * if the day equals the current day." to "The current day is marked with a *."

[6] Page 106

In the Note, remove "and the hard-wired assumption that the week starts on a Sunday"

[6] Page 121

Change "demonstate" to "demonstrate"

[6] Page 128, 129

Change "Booleans" to "boolean values" (note monospace)

[6] Page 135

Remove the sentence "The sole purpose of package nesting is to manage unique names."

[6] Page 141

Change "Recall that you can import public classes only from other packages." to "Recall that you can import only public classes from other packages."

[4] Page 141

In the third line from the bottom, change "packages" to "package".

[4] Page 143

In the last line, change "set the warning border" to "set the warning string".

[6] Page 147

Change "If you like, you can place hyperlinks to other classes or methods anywhere in any of your comments." to "If you like, you can place hyperlinks to other classes or methods anywhere in any of your javadoc comments."

[6] Page 156

Remove "(that is, when i is 1 or 2)" and "(when i is 0)" , so that the remaining clause is "either Employee or Manager".

[6] Page 165

Change "In particular, move common fields and methods (whether abstract or not) to the abstract superclass." to "Move common fields and methods (whether abstract or not) to the superclass (whether abstract or not)."

[6] Page 172

In the numbered list, add 3. before "Compare the classes of this and otherObject." Increment the following numbers.

[4] Page 172

Remove "Judging from this evidence. . ." until the end of the note.

[4] Page 173

In Table 5-1, change the Hash Code column from 140207504 / 140013338 / 884756206 to 69609650 / 69496448 / -2141031506

[4] Page 174

In Table 5-2, change 3030 to 2556 (2x)

[6] Page 179

Change the last word on the page from "classed" to "called"

[6] Page 180/181

Change "relocation/tions/ting" to "reallocation/tions/ting" (3x)

[6] Page 181

Change "(This is different from, and, of course, never larger than, the array list’s capacity.)" to "(This is of course never larger than the array list’s capacity.)"

[6] Page 188

Change "returns a new Integer object initialized to the integer’s value, assuming the specified String represents" to "returns a new Integer object initialized to the integer whose digits are contained in the string s. The string must represent" (2x)

[4] Page 189

Change

System.out.printf("%d %d", new Object[] { new Integer(d), "widgets" } );

to

System.out.printf("%d %s", new Object[] { new Integer(n), "widgets" } );

[6] Page 191

Remove "We discuss reflection in the next section."

[6] Page 198

Change the last line from

while (cl != Object.class);

to

while (cl != null);

[6] Page 199

Remove line 3 (import java.text.*;)

[6] Page 201

Change "arrayCopy" to "arraycopy"

[6] Page 203/204

Change "fundamental" to "primitive" (2x)

[4] Page 206

Change

System.out.printf("%10.4f | %10.4f%n" + y, x, y);

to

System.out.printf("%10.4f | %10.4f%n", x, y);

[4] Page 207

Remove code lines 42 and 43.

[4] Page 215

Change the first java.lang.Comparable API header to java.lang.Comparable<T>. Remove the second java.lang.Comparable<T> header.

[4] Page 220 and 221

In the clone methods, change

return super.clone();

to

return (Employee) super.clone();

Page 221

Change

public Object clone() throws CloneNotSupportedException

to

public Employee clone() throws CloneNotSupportedException

[6] Page 228

Change “Because the TalkingClock defines no constructors” to “Because the TimePrinter class defines no constructors”

[4] Page 231

In the NOTE, change

java ReflectionTest 'TalkingClock$TimePrinter'

to

java ReflectionTest TalkingClock\$TimePrinter

(that is, remove the quotes and add a backslash). Both methods work, but the change matches the preceding text.

[6] Page 233

Change “Note that the TimePrinter class no longer needs to store a beep instance variable. It simply refers to the parameter variable of the method that contains the class definition.” to “Note that the TalkingClock class no longer needs to store a beep instance field. The actionPerformed method of the TimePrinter class simply refers to the beep parameter variable of the start method.”

[4] Page 233 (2x) and 235 (1x)

Change

Timer t = new Timer(1000, listener)

to

Timer t = new Timer(interval, listener)

[4] Page 254

Change /**import java.awt.* to import java.awt.*

[6] Page 251

Change frame.show(); to frame.setVisible(true);

[4] Page 330

In the API note for getActionMap, change "keystrokes to action keys" to "arbitrary objects to Action objects".
In the API note for getInputMap, change "action keys to action objects" to "keystrokes to arbitrary objects"

[4] Page 330

Change released ctrl Y to ctrl released Y

[4] Page 343

Change "Each user interface has a wrapper class..." to "Each user interface component has a wrapper class...".

[4] Page 349

Change "Finally, you add the individual buttons" to "Finally, you add the panel"

[4] Page 349

The word add in "using the add method you have seen before" is in the wrong font.

[4] Page 353

In the first API note, change int cols to int columns

[4] Page 360

Remove code lines 66 - 68

[4] Page 400

Change the four code lines starting with

JSpinner timeSpinner

to

JSpinner timeSpinner = new JSpinner(new 
      SpinnerDateModel(new Date(), null, null, Calendar.HOUR)
      { 
         public void setCalendarField(int field) {} 
      });

[4] Page 402

Change code lines 75 - 78 to
      JSpinner timeSpinner = new JSpinner(new
            SpinnerDateModel(new Date(), null, null, Calendar.HOUR)
            {
               public void setCalendarField(int field) {}
            });

[4] Page 405

In the explanation for the maximum parameter of the javax.swing.SpinnerDateModel constructor, change "The maximum valid value, or null if no lower bound..." to "The maximum valid value, or null if no upper bound..."

[4] Page 412

In the second line from the bottom, change JPopup to JPopupMenu.

[4] Page 422

Below line 28, add a line

add(panel, BorderLayout.CENTER);

[4] Page 432

Change

panel.add(style, bold);

to

panel.add(component, constraints);

[6] Page 443

The bulleted list is wrong (with different errors in two printings). Here is the correct version:

• Connecting the west side of the component with the west side of the container;
• Traversing the width of the component;
• Connecting the east side of the component with the west side of the container.

[4] Page 444

Change

Spring.max(layout.getConstraints(faceLabel).getWidth(),
Spring.max(layout.getConstraints(sizeLabel).getWidth()));

to

Spring.max(layout.getConstraints(faceLabel).getWidth(),
layout.getConstraints(sizeLabel).getWidth()));

(i.e., remove the second Spring.Max()

[4] Page 447

Change "...to the given side of the start container" to "...to the given side of the startcomponent"

[4] Page 457

Change "The icon is a warning icon" to "The icon is a question icon". Change WARNING_MESSAGE to QUESTION_MESSAGE

[6] Page 509

Change “NOTE: The strings used when you define the parameters with the param tag and those used in the getParameter method must match exactly. In particular, both are case sensitive.” to “NOTE: A case-insensitive comparison is used when matching the name attribute value in the param tag and the argument of the getParameter method.”

[6] Page 522, 524

Change

public Enumeration getApplets() { return null; } 

to

public Enumeration<Applet> getApplets() { return null; } 

and

public Iterator getStreamKeys() { return null; }

to

public Iterator<String> getStreamKeys() { return null; }

[6] Page 547

Change

defaultSettings.put("color.red", "0 50 50");

to

defaultSettings.put("color.red", "0");

[4] Page 567

Change se.setCause(e) to se.initCause(e)

[4] Page 571

Change the numbers after StackTraceTest.java: from 8 23 / 8 14 23 / 8 14 14 23 to 17 33 / 17 23 33 / 17 23 23 33

[6] Page 602

Change

java -Dcom.sun.management.jmxremote MyProgram.java

to

java -Dcom.sun.management.jmxremote MyProgram

[6] Page 604

Change void addXxxListener(XxxEvent) to void addXxxListener(XxxListener).

[4] Page 615

Change "displays all instance fields of the evt variable" to "displays all instance fields of the event variable"

[4] Page 630

In the second line of Table 12-2, change b₁₇a₁₆a₁₅... to b₁₇b₁₆a₁₅...

[6] Page 632

Change “The advantage of having the RandomAccessFile class implement both DataInput and DataOutput is that this lets you use or write methods whose argument types are the DataInput and DataOutput interfaces.” to “The RandomAccessFile class implements both DataInput and DataOutput. It is a good idea to use these interfaces for method parameters.”

[4] Page 634

Change Set<String, CharSet> to Map<String, CharSet>.

[5] Page 639

In the API description for CharBuffer decode(ByteBuffer buffer), change "decodes the given character sequence ..." to "decodes the given byte sequence"

[4] Page 658

In the second line from the bottom, change long int nbytes to long nbytes.

[4] Page 660

Lines 76, 77 of the code should be
      Raises the salary of this employee.
      @param byPercent the percentage of the raise

[4] Page 667

Change "The java.util.Date class defines its own readObject/writeObject methods" to "The serializable java.util.Date class defines its own writeObject method". (The wording in the book was correct, but it confused some readers into thinking that Date is externalizable.)

[4] Page 688

In the documentation for createNewFile, change "automatically creates" to "atomically creates".

[4] Page 713

In the second line of the section Generic Code and the Virtual Machine, change "was even able compile" to "was even able to compile".

[4] Page 719

In the third line from the top, change new Pair<String>(10) to new Pair<String>[10]

[4] Page 720

In the tenth line from the bottom, change

								Pair<Employee> = ArrayAlg...
						

to

Pair<Employee> result = ArrayAlg...

[6] Page 723

Change
void set(? super Manager)
? super Manager get()
to
void setFirst(? super Manager)
? super Manager getFirst()

[6] Page 723

Change "with any Manager object (or a subtype such as Executive), but not with an Employee" to "with any value of type Manager, Employee, or Object, but not with a subtype value such as Executive."

[6] Page 726

Change “Of course, in this case, we were not compelled to use a wildcard—there is nothing wrong with using a type parameter, as in the swapHelper method.” to “Of course, in this case, we were not compelled to use a wildcard. We could have directly implemented <T> void swap(Pair<T> p) as a generic method without wildcards.”

[4] Page 735

Add an entry

enum

an enumerated type

3

[6] Page 743

Change "Boolean, 42, 46, 186, 735" to two entries "boolean, 42, 46, 735" and "Boolean, 186"

[6] Page 760

Change "true or false, seeBoolean" to "true or false, seeboolean"

Seventh Edition Volume 2 (JDK 5.0)

[3] Page xvii

In the second line from the bottom, change Example 5-8 to Example 5-12

[4] Page 3

Change "inside the move method of the Ball class." to "inside the addBall method of the BounceFrame class".

Page 12 BounceThread.java

Remove these lines:

203. public static final int STEPS = 1000;
204. public static final int DELAY = 3;

[3] Page 19

Change "of its parent thread, that is, the thread that started it" to "of the thread that constructed it"

[2] Page 30

Change "You must make sure that the thread cannot be interrupted between the test and the insertion." to "You must make sure that no other thread can modify the balance between the test and the transfer action."

[2] Page 40

Remove the first four lines after Synchronized Blocks "However, a Java object ... only one condition".

[2] Page 41

Apply boldface to synchronized (lock) and remove it from System.out.println(. . .)

[2] Page 42

Change $1,200 to $200 and $1,300 to $300

[2] Page 43

In Figure 1-6, change 1200 to 200 and 1300 to 300

[3] Page 49

Change "The call Object head = q.poll(...) returns true for 100 milliseconds ..." to "The call Object head = q.poll(...) tries for 100 milliseconds ..."

[2] Page 64

In the code just above the API notes, change taks.size() to tasks.size().

[4] Page 100

In the API notes for the remove method of java.util.List<E>, change "removes and returns an element at the specified position" to "removes and returns the element at the specified position"

[4] Page 100

In the API notes for java.util.List<E>, add the following before E set(int i, E element):

• E get(int i)
  returns the element at the specified position.

[3] Page 130 Code line 98

Change

return offset < elements.length;

to

return offset < count; 

[4] Page 152, 153 ThreadedEchoServer.java

Remove lines 43, 86. Change the following lines:

22. Runnable r = new ThreadedEchoHandler(incoming);
44. public ThreadedEchoHandler(Socket i)
47. incoming = i;

[4] Page 166

In the API note of void setConnectTimeout(int timeout)/int getConnectTimeout(), change "...the read method of the associated input stream..." to "...the connect method of the associated input stream...". In the API note of void setReadTimeout(int timeout)/int getReadTimeout(), change "...the connect method of the associated input stream..." to "...the read method of the associated input stream...".

Page 175

The Scanner class wraps the InterruptedIOException. For greater clarity, change
Scanner in = new Scanner(s.getInputStream()); String line = in.nextLine();
to
InputStream in = s.getInputStream();// read from in

[2] Page 229

Change "gets a description of all tables in a catalog..." to "returns a description of all tables in a catalog..."

[2] Page 229

Change "The catalog and schema parameters..." to "The catalog and schemaPattern parameters..."

[3] Page 240

Change

stat.releaseSavepoint(svpt) 

to

conn.releaseSavepoint(svpt)

[2] Page 244

In the last two rectangles in the bottom row of Figure 4-9, change ou=people to ou=groups

[4] Page 281

Product.java is the wrong version. The companion code has the correct version, but it is too long to fit in its entirety. Use this abbreviated version:

import java.rmi.*;

public interface Product extends Remote
{ 
   /**
      Gets the description of this product.
      @return the product description
   */
   String getDescription() throws RemoteException;

   final int MALE = 1;
   final int FEMALE = 2;
   final int BOTH = MALE + FEMALE;
}

[4] Page 282

ProductImpl.java is the wrong version. The companion code has the correct version, but it is too long to fit in its entirety. Use this abbreviated version:

import java.rmi.*;
import java.rmi.server.*;

public class ProductImpl extends UnicastRemoteObject implements Product
{ 
   public ProductImpl(String n, int s, int age1, int age2, String h) throws RemoteException
   {  
      name = n;
      ageLow = age1;
      ageHigh = age2;
      sex = s;
      hobby = h;
   }

   public boolean match(Customer c)
   {  
      if (c.getAge() < ageLow || c.getAge() > ageHigh)
         return false;
      if (!c.hasHobby(hobby)) return false;
      if ((sex & c.getSex()) == 0) return false;
      return true;
   }

   public String getDescription() throws RemoteException
   {  
      return "I am a " + name + ". Buy me!";
   }

   private String name, hobby;
   private int ageLow, ageHigh, sex;
}

[3] Page 293

Change

name = (String) data.get();; 

to

name = (String) data.get();

[4] Page 294, 295

ProductImpl.java is the wrong version. The companion code has the correct version, but it is too long to fit in its entirety. Use this abbreviated version:

import java.io.*;
import java.rmi.*;
import java.rmi.activation.*;

public class ProductImpl
   extends Activatable
   implements Product
{ 
   /**
      Constructs a product implementation
      @param id the activation id
      @param data the marshalled construction parameter (containing the product name)
   */
   public ProductImpl(ActivationID id, MarshalledObject data) 
      throws RemoteException, IOException, ClassNotFoundException
   {  
      super(id, 0);
      name = (String) data.get();
      System.out.println("Constructed " + name);
   }

   public String getDescription() throws RemoteException
   {  
      return "I am a " + name + ". Buy me!";
   }

   private String name;
}

[4] Page 296

Change

static Remote register(ActivationDescriptor desc)

to

static Remote register(ActivationDesc desc)

[4] Page 311

Change

System.out.println(orb.object_to_string(impl));

to

System.out.println(orb.object_to_string(ref));

[2] Page 334

Remove the line

JLabel label = new JLabel();

[4] Page 391

Add return this; as the last line of getTableCellRendererComponent so that the code looks like this:

class ColorTableCellRenderer extends JPanel implements TableCellRenderer
{
   public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected,
      boolean hasFocus, int row, int column)
   {
      setBackground((Color) value);
      if (hasFocus)
         setBorder(UIManager.getBorder("Table.focusCellHighlightBorder"));
      else
         setBorder(null);
      return this;
   }
}

[2] Page 425

Change "on the CD" to "in the companion code"

[3] Page 439

In Fig. 6-48, change the callout "minimize icon" to "maximize icon"

[4] Page 443

Change “The JDesktopPane class has no method to return the selected frame. Instead, you must traverse all frames ...” to “Traverse all frames ...”. (Actually, you can get the selected frame by calling JDesktopPane.getSelectedFrame, but we need its index.)

[4] Page 462

Change "... drawn by the CubicCurve3D class ..." to "... drawn by the CubicCurve2D class ..."

[3] Page 462

Change "between 2180 and 180" to "between -180 and 180"

[3] Page 664

Example 8-10: ChartBean2BeanInfo.java has the wrong file. The correct file is

package com.horstmann.corejava;

import java.awt.*;
import java.beans.*;

/**
 The bean info for the chart bean, specifying the 
 icons and the customizer.
*/
public class ChartBean2BeanInfo extends SimpleBeanInfo
{ 
 public BeanDescriptor getBeanDescriptor()
 { 
 return new BeanDescriptor(ChartBean2.class, ChartBean2Customizer.class);
 }

 public Image getIcon(int iconType)
 { 
 String name = "";
 if (iconType == BeanInfo.ICON_COLOR_16x16) name = "COLOR_16x16";
 else if (iconType == BeanInfo.ICON_COLOR_32x32) name = "COLOR_32x32";
 else if (iconType == BeanInfo.ICON_MONO_16x16) name = "MONO_16x16";
 else if (iconType == BeanInfo.ICON_MONO_32x32) name = "MONO_32x32";
 else return null;
 return loadImage("ChartBean2_" + name + ".gif");
 }
}

[4] Page 705

Change http://bugs.sun.com/developer/bugParade/bugs/4030988.html to http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4030988

[4] Page 772

Change

int outputSize= cipher.getOutputSize(inLength);

to

int outputSize= cipher.getOutputSize(blockSize);

[3] Page 788

In the fourth line from the bottom, change "the java.text class" to "the java.textpackage"

[3] Page 807

In the 4th line from the bottom (excluding the CAUTION note), change 10.0E7 to 10.0E8.

[4] Page 811

Change java -encoding Big5 Myfile.java to javac -encoding Big5 Myfile.java.

[2] Page 833

In line 17 of the code for HelloNative.h, change ifdef to #ifdef

[3] Page 836

Change
... a format string "%w.pf" ...
to
... a format string "%w.pf" ...
(w and p should be Roman italic)

[2] Page 861

Change

jint ThrowNew(JNIEnv *env, jclass clazz, const char msg[])

to

jint ThrowNew(JNIEnv *env, jclass cl, const char msg[])

[3] Page 878

Change GetSuperClass to GetSuperclass

[3] Page 927

Change "XML Style Sheet Transformations" to "Extensible Stylesheet Language Transformations"

[4] Page 935

In Figure 12-8, change the rightmost “XML Document” to “Transformed Document (HTML, text, ...)”

# options used by netbeans launcher by default, can be overridden by explicit
# command line switches
netbeans_default_options="-J-Xms32m -J-Xmx128m -J-XX:PermSize=32m -J-XX:MaxPermSize=160m -J-ea -J-Dapple.laf.useScreenMenuBar=true --fontsize 13"
# --- tips for more advanced options you could use ---
# for JDKs where it is supported (for example Sun's JDK 5.0 and newer),
# you can use the following set of options which enable Concurrent Mark and
# Sweep garbage collection algorithm and improve UI responsiveness
# (see FAQ item http://www.netbeans.org/kb/faqs/performance.html#FaqGCPauses)
#netbeans_default_options="-J-Xms32m -J-Xmx128m -J-XX:PermSize=32m -J-XX:MaxPermSize=160m -J-Xverify:none -J-Dapple.laf.useScreenMenuBar=true -J-XX:+UseConcMarkSweepGC -J-XX:+CMSClassUnloadingEnabled -J-XX:+CMSPermGenSweepingEnabled"
# ---

# default location of J2SE JDK, can be overridden by using --jdkhome <dir> switch
netbeans_jdkhome="D:\Program Files\Java\jdk1.5.0_08"

# clusters' paths separated by path.separator (semicolon on Windows, colon on Unices)
#netbeans_extraclusters="/absolute/path/to/cluster1:/absolute/path/to/cluster2"

其中fontsize可以更大,不过本人觉得13够了和netbeans5.0差不多.

2.netbeans5.5中加快代码提示速度
======================================
在选项中 高级选项-->>编辑-->>编辑器设置-->>Java编辑器-->完成窗口自动弹出之前的延时时间 将250设置为0

高级选项-->>编辑-->>编辑器设置-->>Java编辑器--> 属性栏里面把区分大小写的代码完成前面的小勾去掉(默认没有选上即false状态,如果不小心选上请去掉)

3.netbeans5.5将NetBeans的项目编译成本地exe文件
======================================
新建项目->>NetBeans插件模块->>模块套件项目

4.netbeans5.5最好将NetBeans快捷键设为eclipse的模式,本人觉得这样方便eclipse与netbeans共同使用

import  java.util.ArrayList;
import  java.util.List;

// 申明一个泛型类
public   class  GenericClass  ... {
    
     public   static   void  main(String [] args)  ... {
        List < Integer >  list  =   new  ArrayList < Integer > ();
        list.add( 1 );
        list.add( 2 );
         new  Product().prt(list);
    }
}

// 制造一个类用于说明问题
class  Product   ... {
     public   void  prt(List < String >  lt)  ... {
        System.out.println(lt);
    }
}

编译器报错,说无法将Product中的prt(java.util.List<java.lang.String>)应用于(java.util.List<java.lang.Integer>)。前面定义了List<Integer> list = new ArrayList<Integer>()；后面却调用 public void prt(List<String> lt)用list做参数，肯定是错误的用法。编译器报错的行为是很正确的，他帮助你避免了潜在错误的发生。这里要注意泛型的作用：List<Integer>和List<String>虽然看着都是List，但编译器把他们当作不同的class，不能相互替代。这是泛型的基本原则。你可以把他们看成一个是Class1， 一个是Class2， 当然不能给一个需要类型为Class1的参数的方法传一个类型为Class2的参数的方法啦。

再来看上面程序稍微改动一处的情况

import  java.util.ArrayList;
import  java.util.List;

// 申明一个泛型类
public   class  GenericClass  ... {
    
     public   static   void  main(String [] args)  ... {
        List < Integer >  list  =   new  ArrayList < Integer > ();
        list.add( 1 );
        list.add( 2 );
         new  Product().prt(list);
    }
}

// 制造一个类用于说明问题
class  Product < T >   ... {
     public   void  prt(List < String >  lt)  ... {
        System.out.println(lt);
    }
}

编译器说使用了未经检查或不安全的操作，但能编译通过并运行显示 [1, 2]。

这又是为什么呢？就是红色的那一个<T>就变化这么大吗？似乎不是和刚才效果应该一样拉，怎么这回又可以了？

原因是这样的：第次程序里面，只是把class Product改成了class Product<T>，尽管类型T在Product的代码里压根从没用到，但是这个定义把一个普通类（class）变成了原始类型（raw class）。generic class Product<T>在JVM运行时是不存在的,Product这个原始类型不是类型安全的。因为在new Product.prt(list)里面，使用的是原始类型的Product，所以里面的list也会被擦拭成原始类型的，所以类型就符合了，不会有编译错误而可以运行。

虽然这个时候程序尽管可以运行，但其使用泛型的方法，无疑是错误的。 在这里我只是想和大家分析一些泛型的细节问题。要大家通过这个细节明白泛型的细节之处(檫试，原始类型)。具体的内容我就不在说了，很多书都有。推荐java参考大全5edition page264 和 core Java I 7edition Chapter 13. Generic Programming  

The 10 Things You Need to Know About Java SE 6 'Mustang'

Need a digest, summary, compressed form, precis of what's up with Java SE 6 'Mustang', currently in beta ?

Here it is, the top 10 things you need to know.

1. Web Services

All developers get first class support for writing XML web service client applications. No messing with the plumbing, you can expose your APIs as .NET interoperable web services with a simple annotation. Not your style ? Want to handle the XML directly ? Knock yourself out: Mustang adds new parsing and XML to Java object mapping APIs, previously only available in Java EE implementations or the Java Web Services Pack.

2. Scripting

You can now mix in JavaScript with your Java Source code, useful for prototyping, or when you have teams with a variety of skill sets. More advanced developers can plug in their own scripting engines, and mix their favorite scripting language in with Java as they see fit.

Perhaps You ThougHt yOu couldN't program with a scripting language and Java togetheR. Which will yoUBe trYing ?

3. Database

All developers get the updated JDBC 4.0, which is a new upgrade of a well-used API, focusing mainly on making it easier to use, although there are many feature additions like special support for XML as an SQL datatype, and better integration of BLOBs and CLOBs into the APIs. My favorite ease of use things include removal of some JDBC boilerplate, and some of the new annotations which make SQL strings embed better into your JDBC application. Like decorating your getAllUsers() method with an @Query(sql="select * from user") annotation, and that being all you need.

4. More Desktop APIs

Much has been said about this spoonful of sugar (to go with the desktop team's cake), so I will only skim a little. GUI developers get a large number of new tricks to play like the ever popular yet newly incorporated SwingWorker utility to help you with threading in GUI apps, JTable sorting and filtering and a new facility for quick splash screens to quieten impatient users.

5. Monitoring and Management

Really the big deal here is that you don't need do anything special to the startup to be able to attach on demand with any of the monitoring and management tools in Java SE. Mustang adds yet more diagnostic information, and we cobundled the infamous memory heap analysis tool jhat for forensic explorations of those core dumps.

6. Compiler Access

Really aimed at people who create tools for Java development, and for frameworks like JSP or PHP engines that need to generate a bunch of classes on demand, the compiler API opens up programmatic access to javac for in-process compilation of dynamically generate Java code. Not directly intended for the everyday developer, but for those of you deafened by your screaming inner geek, roll up your sleeves and give it a try. And the rest of us will happily benefit from the tools and the improved Java frameworks that use this.

7. Pluggable Annotations

Its becoming a running joke in Java circles, at least some that contain me, that for every wished for feature missing in Java, there's a budding annotation that will solve the problem. Joke no more, because Java tool and framework vendors can put a different smile on your face, defining their own annotations and have core support for plugging in and executing the processors that do the heaving lifting that can make custom annotations so cool.

8. Desktop Deployment

Those of you deploying applications to the desktop will soon discover that its a tale of a large number of smaller changes that add up to a big difference to existing applications. Like better platform look & feels in Swing, LCD text rendering, and snappier GUI performance overall.  Java apps can integrate better with the native platform with things like new access to the System Tray and Start menu of the platform.  At long last, Mustang unifies the Java Plugin and Java WebStart engines which just makes sense. Java WebStart application installation got a much needed makeover.

9. Security

You can have all the security features you like in the platform (and Mustang adds a few more, like the XML-DSIG APIs for creating and manipulating digital signatures), but if you don't have well supported security administrators, your security may be at risk. So Mustang has simplified the job of its security administrators by providing various new ways to access platform native security services such as native PKI and cryptographic services on Windows for secure authentication and communication, GSS/Kerberos services for authentication, and access to LDAP servers for authenticating users.

10. The Ilities: Quality, Compatibility, Stability

You probably knew that Sun has done regular feature releases of the Java SE platform over the last 10 years, so we certainly feel like we've built up some expertise in this area (the ever growing 80,000 test cases and several million lines of code testing conformance being just one aspect of our testing activity), but different from the last release, you probably noticed that people have been downloading snapshots of Mustang for the last fifteen (not just six) months. And what's more they've been filing bugs. And what's even more we've (and some of you!) been fixing them as we go. We're even challenging people to find more. So unlike previous releases, before we even got to beta, we'd fixed a number of quality and regression issues. Doesn't that add up to a better product ? Oh, and by the way, performance is looking better than Java SE 5 'Tiger'. Already..

So now you know all you need to know. Go on, try it !

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