【正文】 area)。 // Assign a radius radius = 20。 } } no value radius allocate memory for radius animation Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 5 Trace a Program Execution public class ComputeArea { /** Main method */ public static void main(String[] args) { double radius。 // Compute area area = radius * radius * 。 double area。 ). ? To debug logic errors (167。 ). ? To bee familiar with Java documentation, programming style, and naming conventions (167。 ) ? To obtain input using the JOptionPane input dialog boxes (167。 – ). ? To use Java operators to write expressions (167。 ). ? To use constants to store permanent data (167。 ). ? To use variables to store data (167。1 9 .1 1 9 .3 i n C h a p t e r 1 9 R e c u r s i o n Ch a p t e r 2 3 A l g o ri t h m E ffi c i e n c y a n d S o rt i n g Ch a p t e r 3 S e l e c t i o n S t a t e m e n t s Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 2 Objectives ? To write Java programs to perform simple calculations (167。Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 1 Chapter 2 Primitive Data Types and Operations Ch a p t e r 1 I n t r o d u c t i o n t o Co m p u t e r s , P r o g ra m s , a n d J a v a Ch a p t e r 2 P ri m i t i v e D a t a T y p e s a n d O p e ra t i o n s Ch a p t e r 4 L o o p s Ch a p t e r 6 A rra y s Ch a p t e r 5 M e t h o d s Ba s i c c o m p u t e r s k i l l s s u c h a s u s i n g W i n d o w s , In t e r n e t E x p l o re r, a n d M i c r o s o f t W o rd 167。167。 ). ? To use identifiers to name variables, constants, methods, and classes (167。 ). ? To program with assignment statements and assignment expressions (167。 ). ? To declare Java primitive data types: byte, short, int, long, float, double, and char (167。 – ). ? To represent a string using the String type. (167。 ). ? (Optional) To obtain input from console (167。 ). ? To distinguish syntax errors, runtime errors, and logic errors (167。 ). Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 3 Introducing Programming with an Example Listing Computing the Area of a Circle This program putes the area of the circle. ComputeArea Run IMPORTANT NOTE: To run the program from the Run button, (1) set c:\Program Files\java\\bin for path, and (2) install slides from the Instructor Resource Website to a directory (., c:\LiangIR) . Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 4 Trace a Program Execution public class ComputeArea { /** Main method */ public static void main(String[] args) { double radius。 // Assign a radius radius = 20。 // Display results (The area for the circle of radius + radius + is + area)。 double area。 // Compute area area = radius * radius * 。 } } no value radius memory no value area allocate memory for area animation Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 6 Trace a Program Execution public class ComputeArea { /** Main method */ public static void main(String[] args) { double radius。 // Assign a radius radius = 20。 // Display results (The area for the circle of radius + radius + is + area)。 double area。 // Compute area area = radius * radius * 。 } } 20 radius memory area pute area and assign it to variable area animation Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 8 Trace a Program Execution public class ComputeArea { /** Main method */ public static void main(String[] args) { double radius。 // Assign a radius radius = 20。 // Display results (The area for the circle of radius + radius + is + area)。 area = radius * radius * 。 // Compute the second area radius = 。 (The area is “ + area + for radius +radius)。 // Declare x to be an // integer variable。 // Declare radius to // be a double variable。 // Declare a to be a // character variable。 // Assign 1 to x。 // Assign to radius。A39。A39。 Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 13 Declaring and Initializing in One Step ?int x = 1。 Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 14 Constants final datatype CONSTANTNAME = VALUE。 final int SIZE = 3。 displays , not , and ( )。 long x = 1000000。 Liang, Introduction to Java Programming, Sixth Edition, (c) 2020 Pearson Education, Inc. All rights reserved. 0132221586 23 Integer Literals An integer literal can be assigned to an integer variable as long as it can fit into the variable. A pilation error would occur if the literal were too large for the variable to hold. For example, the statement byte b = 1000 would cause a pilation error, because 1000 cannot be stored in a variable of the byte type. An integer literal is assumed to be of the int type, whose value is between 231 (2147483648) to 231–1 (2147483647). To denote an integer literal of the long type, append it with the letter L or l. L is