java语言程序设计基础篇(第八版)课件第三章--机械工业出版报社--李娜译
合集下载
java学习
JavacWelcome.java 编译器(javac.exe)对源文件Welcome.java进行编译 编译生成由字节代码(byte code)组成的二进制程序， 即Welcome.class文件 Java Welcome 通过Java虚拟机中的Java解释器(java.exe)来解释执 行其字节码文件。 Java应用程序总是从主类的main方法开始执行 注意：此时不要加扩展名.class
类库等
Java开发工具包括：
Javac：Java编译器，用来将java程序编译成
Bytecode。 Java：Java解释器，执行已经转换成Bytecode的 java应用程序。 Jdb：Java调试器， 用来调试java程序 Javap：反编译，将类文件还原回方法和变量。 Javadoc：文档生成器,创建HTML文件。 Appletviwer：Applet解释器, 用来解释已经转换 成Bytecode的java小应用程序。
JRE——java runtime environment. JRE是由JVM 、 java platform 核心类以及相关支撑 文件组成。 JRE是可以在其上运行、测试和传输应用程序的 Java平台。 jRE不含开发工具——编译器、调速器和其他工具。
Java术语——API
API——Application programming interface 应用程序接口，包括为开发Java程序而预定义的类 和接口。 API包括数百个类—sun公司预先编好的代码，你 可以在编程中充分利 用它们的功能。 JDK 包含JVM和其他工具，以及所有的API和
设置环境变量 我的电脑(右键)属性高级系统设置环境变量 编辑变量path 在path变量值里 添加java JDK bin目录的路径 添加java JDK jre bin目录的路径 注意不同的路径之间用 ’;’ 分割 创建或者添加classpath变量值 .;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\to ols.jar /tianshuai1111/article/details /7367700
java 课件 第三章
getCharsDemo.java equalsDemo.java EqualsNotEqualTo.java indexOfDemo.java StringReplace.java
字符串常量对方法的访问示例：
"Hello".toUpperCase() ==> "HELLO" "Hello".length() ==> 5 字符串常量不是char类型一维数组，不存在‘\0’结束符。 字符串和char数组可以通过相应方法转换： char[] data = "Car".toCharArray(); 则：data = {'C','a','r'} copyValueOf(data) ==> "Car"
while循环语句的格式是：
[initalization] while (expressBool){ statements; [iteration;] }
while语句循环执行的顺序是：
◦ ◦ ◦ ◦ ◦ ◦ 执行初始化initalization(如果有)； 计算表达式expressBool的值； 若expressBool值为true，则执行循环体statements； 执行迭代部分iteration(如果有)； 返回到2； 若expressBool值为false，则终止while循环。
虽然在声明数组的格式中，允许方括号在数组名的 左边或者右边，但这种方式不适合数组句法的其它 部分。 必须首先将低位维初始化，再能对它后面的各位依 次初始化。 利用对每维元素的分步初始化，可以创建非矩形数 组的数组。
TwoDArray.java Matrix.java ThreeDMatrix.java
字符串常量对方法的访问示例：
"Hello".toUpperCase() ==> "HELLO" "Hello".length() ==> 5 字符串常量不是char类型一维数组，不存在‘\0’结束符。 字符串和char数组可以通过相应方法转换： char[] data = "Car".toCharArray(); 则：data = {'C','a','r'} copyValueOf(data) ==> "Car"
while循环语句的格式是：
[initalization] while (expressBool){ statements; [iteration;] }
while语句循环执行的顺序是：
◦ ◦ ◦ ◦ ◦ ◦ 执行初始化initalization(如果有)； 计算表达式expressBool的值； 若expressBool值为true，则执行循环体statements； 执行迭代部分iteration(如果有)； 返回到2； 若expressBool值为false，则终止while循环。
虽然在声明数组的格式中，允许方括号在数组名的 左边或者右边，但这种方式不适合数组句法的其它 部分。 必须首先将低位维初始化，再能对它后面的各位依 次初始化。 利用对每维元素的分步初始化，可以创建非矩形数 组的数组。
TwoDArray.java Matrix.java ThreeDMatrix.java
java语言程序设计基础篇(第八版)课件PPT第八章
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
3
OO Programming Concepts
Object-oriented programming (OOP) involves programming using objects. An object represents an entity in the real world that can be distinctly identified. For example, a student, a desk, a circle, a button, and even a loan can all be viewed as objects. An object has a unique identity, state, and behaviors. The state of an object consists of a set of data fields (also known as properties) with their current values. The behavior of an object is defined by a set of methods.
5
Classes
Classes are constructs that define objects of the same type. A Java class uses variables to define data fields and methods to define behaviors. Additionally, a class provides a special type of methods, known as constructors, which are invoked to construct objects from the class.
3
OO Programming Concepts
Object-oriented programming (OOP) involves programming using objects. An object represents an entity in the real world that can be distinctly identified. For example, a student, a desk, a circle, a button, and even a loan can all be viewed as objects. An object has a unique identity, state, and behaviors. The state of an object consists of a set of data fields (also known as properties) with their current values. The behavior of an object is defined by a set of methods.
5
Classes
Classes are constructs that define objects of the same type. A Java class uses variables to define data fields and methods to define behaviors. Additionally, a class provides a special type of methods, known as constructors, which are invoked to construct objects from the class.
java语言程序设计基础篇(第八版)课件PPT第四章 机械工业出版报社 李娜译
Suppose that you need to print a string (e.g., "Welcome to Java!") a hundred times. It would be tedious to have to write the following statement a hundred times: System.out.println("Welcome to Java!"); So, how do you solve this problem?
int count = 0;
(count < 2) is false since count is 2 now
while (count < 2) {
System.out.println("Welcome to Java!"); count++; }
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
4
Objectives
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 5
count++; }
count = 0;
Loop C o n tin u a tio n C o n d itio n ? tru e S ta te m e n t(s) (lo o p b o d y)
int count = 0;
(count < 2) is false since count is 2 now
while (count < 2) {
System.out.println("Welcome to Java!"); count++; }
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
4
Objectives
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 5
count++; }
count = 0;
Loop C o n tin u a tio n C o n d itio n ? tru e S ta te m e n t(s) (lo o p b o d y)
Java语言程序设计基础教程课件(第3章)
3.2.2类声明
Java中类声明的语法如下：
[public][abstract|final] class className [extends superclassName] [implements interfaceNameList] { …… }
其中，修饰符public，abstract，final 说明了类的属 性，className为类名，superclassName为类的父 类的名字，interfaceNameList为类所实现的接口列 表
3.2.3类体
Java中类体定义的语法如下： class className {[public | protected | private ] [static] [final] [transient] [volatile] type variableName; //成员变量的语法 [public | protected | private ] [static] [final | abstract] [native] [synchronized] returnType methodName([paramList]) [throws exceptionList] {statements} //成员方法的语法 }
1．方法声明
方法声明包括方法名、返回类型和外部参数。 其中参数的类型可以是简单数据类型，也可以 是复合数据类型（又称引用数据类型）。
【例3-1】 展示简单数据类型与引用数据的区别的例子。
import java.io.*; public class PassTest { float ptValue; public void changeInt(int value) { value = 55; // 在方法内部对值参数进行了修改 } public void changeObjValue(PassTest ref) { ref.ptValue = 99f; // 在方法内部对引用参数进行了修改 } public static void main(String args[]) { int val; PassTest pt = new PassTest(); val = 11; System.out.println("初始的整型值是: " + val); pt.changeInt(val); // 值参数 System.out.println("改变后整型值是: " + val); pt.ptValue = 101f; System.out.println("初始的整型值是: " + pt.ptValue); pt.changeObjValue(pt); // 引用类型的参数 System.out.println("改变后整型值是: " + pt.ptValue); } }
java语言程序设计基础篇(第八版)课件第三章--机械工业出版报社--李娜译
Run
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
6
One-way if Statements
Run
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
10
Mathematics Basis for the Game
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
2
Objectives
To declare boolean type and write Boolean expressions using comparison operators (§3.2). To program AdditionQuiz using Boolean expressions (§3.3). To implement selection control using one-way if statements (§3.4) To program the GuessBirthday game using one-way if statements (§3.5). To implement selection control using two-way if statements (§3.6). To implement selection control using nested if statements (§3.7). To avoid common errors in if statements (§3.8). To program using selection statements for a variety of examples (BMI, ComputeTax,
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
6
One-way if Statements
Run
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
10
Mathematics Basis for the Game
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
2
Objectives
To declare boolean type and write Boolean expressions using comparison operators (§3.2). To program AdditionQuiz using Boolean expressions (§3.3). To implement selection control using one-way if statements (§3.4) To program the GuessBirthday game using one-way if statements (§3.5). To implement selection control using two-way if statements (§3.6). To implement selection control using nested if statements (§3.7). To avoid common errors in if statements (§3.8). To program using selection statements for a variety of examples (BMI, ComputeTax,
java语言程序设计基础篇(第八版)_完整版ppt课件
• 例1.1 设计一个程序，其运行后接受用 户输入的两个数，然后计算其平均值， 并输出结果。
• 解答：解决问题的过程为： 1）输入两个数存放于变量a和b中； 2）计算(a+b)/2，并将其结果存储于变量
7
1.1.1计算机的组成与运行
• “文字处理、绘制图形、玩游戏、制作动 画、听音乐、上网查询信息和观看网络 电影等”是怎样与“执行计算和逻辑判 断”联系起来呢？
• 实际上，我们使用的计算机即计算机系 统包含两大部分，一是硬件本身，它包 括键盘、鼠标、显示器、磁盘和主机 （箱）等；另一是软件。
8
1.1.1计算机的组成与运行
• 3）内存单元。内存单元是计算机中存取 速度快、容量相对较少的储存部分。它 能够记忆来自输入单元的信息，因而能 够在需要的时候立即处理这些信息。内 存单元还能够记忆被处理过的信息，直 到输出单元把信息放到输出设备上。内 存单元经常被称为内存或主存。内存在 计算机电源关闭后将不起作用。
14
1.1算机的组成与运行
• 软件与程序是不等价的，简单说，软件 = 程序 + 相关文档资料。
• 计算机硬件是在程序的指令集控制下处 理数据的。计算机程序控制着计算机， 使它按顺序执行一系列动作，这些动作 是由程序员规划的，并用指令描述的。
• 各种计算机无论外观差别有多大，每一 台计算机实际上都可划分为五个逻辑单 元（或称五大部分），如图1-1所示。
2
学习目标
• 4. 了解Java语言的特点，理解Java 程序上机执行过程，掌握简单的Java 应用程序和Java applet程序的基本 结构，能上机执行Java 应用程序和 Java applet程序；能初步使用格式 化输入输出语句。
• 5. 初步理解对象和类的概念，掌握表 示它们的UML图形符号。
• 解答：解决问题的过程为： 1）输入两个数存放于变量a和b中； 2）计算(a+b)/2，并将其结果存储于变量
7
1.1.1计算机的组成与运行
• “文字处理、绘制图形、玩游戏、制作动 画、听音乐、上网查询信息和观看网络 电影等”是怎样与“执行计算和逻辑判 断”联系起来呢？
• 实际上，我们使用的计算机即计算机系 统包含两大部分，一是硬件本身，它包 括键盘、鼠标、显示器、磁盘和主机 （箱）等；另一是软件。
8
1.1.1计算机的组成与运行
• 3）内存单元。内存单元是计算机中存取 速度快、容量相对较少的储存部分。它 能够记忆来自输入单元的信息，因而能 够在需要的时候立即处理这些信息。内 存单元还能够记忆被处理过的信息，直 到输出单元把信息放到输出设备上。内 存单元经常被称为内存或主存。内存在 计算机电源关闭后将不起作用。
14
1.1算机的组成与运行
• 软件与程序是不等价的，简单说，软件 = 程序 + 相关文档资料。
• 计算机硬件是在程序的指令集控制下处 理数据的。计算机程序控制着计算机， 使它按顺序执行一系列动作，这些动作 是由程序员规划的，并用指令描述的。
• 各种计算机无论外观差别有多大，每一 台计算机实际上都可划分为五个逻辑单 元（或称五大部分），如图1-1所示。
2
学习目标
• 4. 了解Java语言的特点，理解Java 程序上机执行过程，掌握简单的Java 应用程序和Java applet程序的基本 结构，能上机执行Java 应用程序和 Java applet程序；能初步使用格式 化输入输出语句。
• 5. 初步理解对象和类的概念，掌握表 示它们的UML图形符号。
java语言程序设计-基础篇--课件(第8章)英文
Example: Defining Classes and Creating Objects
10
Objective: Demonstrate creating objects, accessing data, and using methods.
TV
TestTV Run
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
1
Chapter 8 Objects and Classes
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
Motivations
2
After learning the preceding chapters, you are capable of solving many programming problems using selections, loops, methods, and arrays. However, these Java features are not sufficient for developing graphical user interfaces and large scale software systems. Suppose you want to develop a graphical user interface as shown below. How do you program it?
Java语言程序设计 第三章.ppt
if-else 语句分为：
– 单分支（if） – 双分支（if-else） – 多分支结构（if-else-if）
9if-else 语句if (condition) { action1;
}
条件？ Y
语句序列
if (condition) {
action1;
} else { action2;
Y 条件
– int[ ] numbers; numbers = {1, 2, 3}; //error
– int[ ] numbers = new int[3]{1, 2, 3}; //error
数组元素的访问
4
二维数组
演示二维数组的使用
数组的定义：int[ ][ ] numbers; 数组的空间分配：numbers = new int[3][4]; 数组元素的初始化：
– int[][] numbers = new int[][]{{1,2,3},{4,5,6}} //ok – int[][] numbers = {{1,2,3},{4,5,6}} //ok – int[][] numbers = {{1,2,3},{4,5},{6}} //ok – int[][] numbers = new int[][]{1,2,3,4,5,6} //error – int[][] numbers = new int[2][]{{1,2,3},{4,5,6}} //error
数组元素的访问
5
二维数组
Java的二维数组，每一行是一个一维数组。在 C语言中，要求每一个一维数组列数相同，但 Java允许每一行的列数不同，如：
– int[][] numbers; //定义 – numbers = new int[3][]; //分配空间 – numbers[0] = new int[5]; – numbers[1] = new int[3]; – numbers[2] = new int[2];
– 单分支（if） – 双分支（if-else） – 多分支结构（if-else-if）
9if-else 语句if (condition) { action1;
}
条件？ Y
语句序列
if (condition) {
action1;
} else { action2;
Y 条件
– int[ ] numbers; numbers = {1, 2, 3}; //error
– int[ ] numbers = new int[3]{1, 2, 3}; //error
数组元素的访问
4
二维数组
演示二维数组的使用
数组的定义：int[ ][ ] numbers; 数组的空间分配：numbers = new int[3][4]; 数组元素的初始化：
– int[][] numbers = new int[][]{{1,2,3},{4,5,6}} //ok – int[][] numbers = {{1,2,3},{4,5,6}} //ok – int[][] numbers = {{1,2,3},{4,5},{6}} //ok – int[][] numbers = new int[][]{1,2,3,4,5,6} //error – int[][] numbers = new int[2][]{{1,2,3},{4,5,6}} //error
数组元素的访问
5
二维数组
Java的二维数组，每一行是一个一维数组。在 C语言中，要求每一个一维数组列数相同，但 Java允许每一行的列数不同，如：
– int[][] numbers; //定义 – numbers = new int[3][]; //分配空间 – numbers[0] = new int[5]; – numbers[1] = new int[3]; – numbers[2] = new int[2];
郑莉版JAVA复习
抽象类声明的语法形式为
abstract class Number { ... }
33
JAVA语言程序设计
清华大学 郑莉
抽象方法
声明的语法形式为
public abstract <returnType> <methodName>(...);
仅有方法头，而没有方法体和操作实现 具体实现由当前类的不同子类在它们各自 的类声明中完成
类名 变量名
– 声明一个引用变量时并没有对象生成
对象的创建
– 生成实例的格式： new <类名>() 其作用是：
在内存中为此对象分配内存空间 返回对象的引用(reference ，相当于对象的存储地址)
9
JAVA语言程序设计
清华大学 郑莉
数据成员
类变量
– 也称为静态变量，声明时需加static修饰符，类变量在整 个类中只有一个值 – 类初始化的同时就被赋值 – 适用情况
类型 同一类 同一包中的 子类 同一包中的 非子类 不同包中的 子类 不同包中的 非子类
private yes
无修饰
protected yes
public yes
yes
no
no no no
yes
yes no no
yes
yes yes no
yes
yes yes yes
16
JAVA语言程序设计
清华大学 郑莉
– 也可以包含基本数据类型的数据成员，但它们都默认为static和 final
清华大学 郑莉
第四章 类的重用
类的继承 Object类 终结类与终结方法 抽象类 清华大学 郑莉
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807
The boolean Type and Operators
boolean b = (1 > 2);
4
Comparison Operators
Operator Name
<
less than
<=
less than or equal to
>
greater than
>=
greater than or equal to
==
equal to
!=
not equal to
Chapter 3 Selections
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 01312130807
Motivations
Often in a program you need to compare two values, such as whether i is greater than j. Java provides six comparison operators (also known as relational operators) that can be used to compare two values. The result of the comparison is a Boolean value: true or fale Math Learning Tool
This example creates a program to let a first grader practice additions. The program randomly generates two single-digit integers number1 and number2 and displays a question such as “What is 7 + 9?” to the student. After the student types the answer, the program displays a message to indicate whether the answer is true or false.
If you assigned a negative value for radius in Listing 2.1, ComputeArea.java, the program would print an invalid result. If the radius is negative, you don't want the program to compute the area. How can you deal with this situation?
2
Objectives
To declare boolean type and write Boolean expressions using comparison operators (§3.2). To program AdditionQuiz using Boolean expressions (§3.3). To implement selection control using one-way if statements (§3.4) To program the GuessBirthday game using one-way if statements (§3.5). To implement selection control using two-way if statements (§3.6). To implement selection control using nested if statements (§3.7). To avoid common errors in if statements (§3.8). To program using selection statements for a variety of examples (BMI, ComputeTax, SubtractionQuiz) (§3.9-3.11). To generate random numbers using the Math.random() method (§3.9). To combine conditions using logical operators (&&, ||, and !) (§3.12). To program using selection statements with combined conditions (LeapYear, Lottery) (§§3.133.14). To implement selection control using switch statements (§3.15). To write expressions using the conditional operator (§3.16). To format output using the System.out.printf method and to format strings using the String.format method (§3.17). To examine the rules governing operator precedence and associativity (§3.18). (GUI) To get user confirmation using confirmation dialogs (§3.19).
The boolean Type and Operators
boolean b = (1 > 2);
4
Comparison Operators
Operator Name
<
less than
<=
less than or equal to
>
greater than
>=
greater than or equal to
==
equal to
!=
not equal to
Chapter 3 Selections
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 01312130807
Motivations
Often in a program you need to compare two values, such as whether i is greater than j. Java provides six comparison operators (also known as relational operators) that can be used to compare two values. The result of the comparison is a Boolean value: true or fale Math Learning Tool
This example creates a program to let a first grader practice additions. The program randomly generates two single-digit integers number1 and number2 and displays a question such as “What is 7 + 9?” to the student. After the student types the answer, the program displays a message to indicate whether the answer is true or false.
If you assigned a negative value for radius in Listing 2.1, ComputeArea.java, the program would print an invalid result. If the radius is negative, you don't want the program to compute the area. How can you deal with this situation?
2
Objectives
To declare boolean type and write Boolean expressions using comparison operators (§3.2). To program AdditionQuiz using Boolean expressions (§3.3). To implement selection control using one-way if statements (§3.4) To program the GuessBirthday game using one-way if statements (§3.5). To implement selection control using two-way if statements (§3.6). To implement selection control using nested if statements (§3.7). To avoid common errors in if statements (§3.8). To program using selection statements for a variety of examples (BMI, ComputeTax, SubtractionQuiz) (§3.9-3.11). To generate random numbers using the Math.random() method (§3.9). To combine conditions using logical operators (&&, ||, and !) (§3.12). To program using selection statements with combined conditions (LeapYear, Lottery) (§§3.133.14). To implement selection control using switch statements (§3.15). To write expressions using the conditional operator (§3.16). To format output using the System.out.printf method and to format strings using the String.format method (§3.17). To examine the rules governing operator precedence and associativity (§3.18). (GUI) To get user confirmation using confirmation dialogs (§3.19).