动画跟踪程序的执行public class ComputeArea 内存/** Main method */public static void main(Stringl args) 半径radius无值double radius:double area,面积area无值// Assign a radiusradius =20;为面积area分配内存// Computeareaarea =radius * radius * 3.14159;//DisplayresultsSystem.out.println("The area for the circle of radius "+radius +" is" + area);1Liang,Introduction to Java Programming,EighthEdition,(c)2011Pearson Education,Inc.All?rightsreserved.0132130807
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 6 跟踪程序的执行 public class ComputeArea { /** Main method */ public static void main(String[] args) { double radius; double area; // Assign a radius radius = 20; // Compute area area = radius * radius * 3.14159; // Display results System.out.println("The area for the circle of radius " + radius + " is " + area); } } 半径radius 无值 内存 面积area 无值 为面积area 分配内存 动画
动画跟踪程序的执行给半径radius赋值20public class ComputeArea/** Main method */public static void main(Stringll args) (20半径radiusdouble radius;double area;面积area无值// Assign a radiusradius=20//Computeareaarea=radius*radius*3.14159;//DisplayresultsSystem.out.println("The area for the circle of radius "+radius +" is " + area);1Liang,Introduction to Java Programming,EighthEdition,(c)2011Pearson Education,Inc.Allrightsreserved.0132130807
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 7 跟踪程序的执行 public class ComputeArea { /** Main method */ public static void main(String[] args) { double radius; double area; // Assign a radius radius = 20; // Compute area area = radius * radius * 3.14159; // Display results System.out.println("The area for the circle of radius " + radius + " is " + area); } } 半径radius 20 面积area 无值 给半径radius 赋值20 动画
动画探究程序执行public class ComputeArea内存/** Main method */public static void main(Stringl args) (20半径radiusdouble radius;double area;面积area1256.636// Assign a radiusradius = 20;计算面积并将其//Computeareaarea=radius*radius*3.14159赋值给变量area//DisplayresultsSystem.out.println("The area for the circle of radius " +radius +" is"+area);人Liang,Introduction to Java Programming,EighthEdition,(c)2011Pearson Education,Inc.Allrightsreserved.0132130807
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 8 探究程序执行 public class ComputeArea { /** Main method */ public static void main(String[] args) { double radius; double area; // Assign a radius radius = 20; // Compute area area = radius * radius * 3.14159; // Display results System.out.println("The area for the circle of radius " + radius + " is " + area); } } 半径radius 20 内存 面积area 1256.636 计算面积并将其 赋值给变量area 动画
动画探究程序执行public class ComputeArea f内存/** Main method */public static void main(Stringll args) (半径radius20double radius;double area;面积area1256.636/l Assign a radiusradius = 20;// Compute areaarea=radius*radius*3.14159;向控制台打印一条消息//DisplayresultsSystem.out.println("Theareaforthe circleofradius"+radius +"is"+area);LOXCAConndPromptc:Vaok>java ConputeAreaTheareaforthecircleofradius20.0is1256.636人Liang,Introduction to Java Programming,EighthEdition,(c)2011Pearson Education,Inc.Allrightsreserved.0132130807
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 9 探究程序执行 public class ComputeArea { /** Main method */ public static void main(String[] args) { double radius; double area; // Assign a radius radius = 20; // Compute area area = radius * radius * 3.14159; // Display results System.out.println("The area for the circle of radius " + radius + " is " + area); } } 半径radius 20 内存 面积area 1256.636 向控制台打印一条消息 动画
从控制台读取输入1.创建一个Scanner类型的对象Scanner input = new Scanner(System.in);2.使用方法nextO、nextByteO、nextShortOnextInt()、nextLongO、nextFloatO、nextDouble(或nextBooleanQ 来获取一个string、byte、short、intlong、float、double或 boolean 的值。例如:1System.out.print("Enter a double value:Scanner input = new Scanner (System.in);double d = input.nextDouble()ComputeAreaWithConsolelnputComputeAverageRunRunLiang,Introduction toJava Programming,EighthEdition,(c)2011PearsonEducation,Inc.All10rightsreserved.0132130807
Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 10 从控制台读取输入 1. 创建一个Scanner类型的对象 Scanner input = new Scanner(System.in); 2. 使用方法next() 、nextByte() 、nextShort() 、 nextInt() 、 nextLong() 、nextFloat() 、nextDouble()或 nextBoolean() 来获取一个string、 byte、 short、int、 long、float、double或 boolean 的值。例如： System.out.print("Enter a double value: "); Scanner input = new Scanner(System.in); double d = input.nextDouble(); ComputeAreaWithConsoleInput Run ComputeAverage Run