第三章 java流程控制语句.ppt

语句的概念 java程序的执行遵循一定的流程，流程是程序执行的顺序。 流程控制语句是控制程序中各语句执行顺序的语句，是程序中非常关键和基本的部分。流程控制语句可以把单个的语句组合成有意义的、能够完成一定功能的小逻辑块。 class Max{ public double getMax(double a,double b){ double max; max=a; if(maxb){ max=b; } return max; } } public class Ex3_1{ public static void main(String[] args){ Max obj=new Max(); System.out.println(max=+obj.getMax(3.14,3.1415926)); } } import java.util.*; class Leap{ public boolean isLeap(int year){ if((year%4==0)(year%100!=0)||(year%400==0)){ return true; } else{ return false; }}} public class Ex3_2{ public static void main(String[] args){ int year; System.out.println(输入一个年份：); Scanner reader=new Scanner(System.in); year=reader.nextInt(); Leap obj=new Leap(); if(obj.isLeap(year)){ System.out.println(year+是闰年。); } else{ System.out.println(year+不是闰年。); }}} public class Ex3_3{ public static void main(String[] args){ (new Letter()).judgeLetter(); } } class Letter{ public void judgeLetter(){ char ch; ch=(char)(java.lang.Math.random()*128); if(ch ) System.out.println(是不可显示字符！); else if(ch=ach=z) System.out.println(ch+是小写字母！); else if(ch=Ach=Z) System.out.println(ch+是大写字母！); else if(ch=0ch=9) System.out.println(ch+是数字！); else System.out.println(ch+是其他符号！); }} import java.util.*; public class Ex3_4{ public static void main(String[] args){ (new Grade()).toGrade(); }} class Grade{ public void toGrade(){ int score,m; Scanner reader=new Scanner(System.in); System.out.println(输入成绩：); score=reader.nextInt(); if(score0||score100){ System.out.println(data error!); } else{ m=score/10; switch(m) {case 9: case 10: System.out.println(The grade is A.);break; case 8: System.out.println(The grade is B.);break; case 7: System.out.println(The grade is C.);break; case 6: System.out.println(The grade is D.);break; default: System.out.println(The grade is E.);break; }}}} IF嵌套语句 if (条件1) { if ( 条件2) { /