Java语言程序设计_基础篇_中文ppt_第五章 Java语言程序设计_基础篇_中文ppt_第五章 第5章 方 法 Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 开放问题分别求出 1 到10、20 到 30、 35到 45的整数和。 Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 问题int sum = 0; for (int i = 1; i = 10; i+) sum += i; System.out.println(Sum from 1 to 10 is + sum); sum = 0; for (int i = 20; i = 30; i+) sum += i; System.out.println(Sum from 20 to 30 is + sum); sum = 0; for (int i = 35; i = 45; i+) sum += i; System.out.println(Sum from 35 to 45 is + sum); Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 问题int sum = 0; for (int i = 1; i = 10; i+) sum += i; System.out.println(Sum from 1 to 10 is + sum); sum = 0; for (int i = 20; i = 30; i+) sum += i; System.out.println(Sum from 20 to 30 is + sum); sum = 0; for (int i = 35; i = 45; i+) sum += i; System.out.println(Sum from 35 to 45 is + sum); Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 解决方案public static int sum(int i1, int i2) int sum = 0; for (int i = i1; i = i2; i+) sum += i; return sum; public static void main(String args) System.out.println(Sum from 1 to 10 is + sum(1, 10); System.out.println(Sum from 20 to 30 is + sum(20, 30); System.out.println(Sum from 35 to 45 is + sum(35, 45); Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 学习目标定义方法、调用方法以及传参数给方法 (第5.2-5.5 节)。 开发模块化的、易读、易调试以及易维护的可重用 代码 (第5.6节)。 使用方法重载和理解歧义重载(第5.7节)。 设计和实现重载方法(第5.8节)。 确定变量的作用域(第5.9节)。 了解如何使用 Math 类中的方法 (第5.10-5.11节)。 学习方法抽象的概念 (第5.12节)。 使用逐步求精的方法设计和实现方法(第5.12节)。 Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 定义方法方法是为完成一个操作而组合在一起的语句。Define a method return value type method name formal parameters Invoke a method modifier method header method body int z = max(x, y); public static int max(int num1, int num2) int result; if (num1 num2) result = num1; else result = num2; return result; parameter list actual parameters (arguments) method signature return value Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 方法签名方法签名包括方法名和参数列表。Define a method return value type method nam e formal parameters Invoke a method modifier method header method body int z = max(x, y); public static int max(int num1, int num2) int result; if (num1 num2) result = num1; else result = num2; return result; parameter list actual parameters (arguments) method signature return value Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 形式参数定义在方法头的变量被称作形式参数。Define a method return value type method name formal parameters Invoke a method modifier method header method body int z = max(x, y); public static int max(int num1, int num2) int result; if (num1 num2) result = num1; else result = num2; return result; parameter list actual parameters (arguments) method signature return value Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 实际参数当方法被调用时，就传递给参数一个值。这个值被称作实际参 数或实参。Define a method return value type method name formal parameters Invoke a method modifier method header method body int z = max(x, y); public static int max(int num1, int num2) int result; if (num1 num2) result = num1; else result = num2; return result; parameter list actual parameters (arguments) method signature return value Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 返回数据类型方法可以返回一个值。returnValueType是方法返回值的数据 类型。假如方法不返回值，那么returnValueType就是关键字 void。 例如：在 main 方法中returnValueType 就是void。Define a method return value type method name formal parameters Invoke a method modifier method header method body int z = max(x, y); public static int int result; if (num1 num2) result = num1; else result = num2; return result; parameter list max( int num1, int num2) actual parameters (arguments) method signature return value Liang, Introduction to Java Programming, Eighth Edition, (c) 2021 Pearson Education, Inc. All rights reserved. 0132130807 Java语言程序设计_基础篇_中文ppt_第五章 调用方法测试 max方法