被三整除的数
public class DivideTop53{
public static void main(String args[]){
int num = 0, i = 1;
while (i <=100){
if (i%3 == 0){
num++;
System.out.println(i + " ");
}
i++;
if (num==5) break;
}
}
}

斐波那契数列基础版
public class Fibonacci41{
public static void main(String args []){
int num=1,a=0,b=0,c=1;
while(num<6){
num++;
b=c;
c=a+b;
a=b;
}
System.out.println(c);
System.out.println(num);
}
}
忘了能不能行了。。。明天再尝试运行一下吧
下一个升级版

斐波那契数列升级版
可以手动输入想要的位数
import java.util.Scanner;
public class Fibonacci42{
public static void main(String args []){
Scanner in=new Scanner(System.in);
System.out.println("请输入你想得到第几位的斐波那契数");
int n=in.nextInt();
int a=1,b=1;
if (n<=0){
System.out.println("你在开玩笑吧→.→");
System.out.println("都知道斐波那契数列是从1开始的o.olll");
}
else if (n<3){
System.out.println("你想要的是第" + n + "位的斐波那契数对吧\(^o^)/YES！");
System.out.println("您要的结果是⇒" + "1");}
else if (n>=3){
int num=2,c=1;
while(num<n){
num++;
b=c;
c=a+b;
a=b;
}
System.out.println("你想要的是第" + n + "位的斐波那契数对吧\(^o^)/YES！");
System.out.println("您要的结果是⇒" + c);
}
}
}

有1三个整数x=10,y=39,z=3，请把这三个数由小到大输出
public class l2b{
public static voidmain(String [] arg){
int x=10,y=39, z=3;
inta=(x<y)?x:y;
intb=(a<z)?a:z;
intc=(x>y)?x:y;
int d=(c>z)?c:z;
System.out.println(b+"<"+a+"<"+d);
}
}

学习成绩>=90分的同学用A表示，60-89分之间的用B表示，60分以下的用C表示。
小明同学得的85分时输出结果。
public class result{
public static voidmain(String [] args){
inti=85;
if(i>60)
{if(i>=90)
System.out.println("A");
elseSystem.out.println("B");
}
elseSystem.out.println("C");
}
}

打印出如下图案
*
**
***
****
*****
******
*******
public class star1{
public static void main(String [] args){
for (int n=1;n<=5;n++){
int hs=n;
System.out.println();
for (int i=1;i<=hs;i++)
{
System.out.print("*");
}
}
}
}

构造函数调用和普通调用
public class Person{
int id;
int age;
Person(int _id, int _age){
id = _id;
age = _age;
}
public static void main(String args []){
Person tom = new Person(1,25);
}
}
public class People{
int id;
int age=20;
void People(int _id, int _age){
id = _id;
age = _age;
}
public static void main(String args []){
People tom = new People();
tom.People(1,25);
}
}

插播一层
约定俗成命名规则
1.类名的首字母大写
eg HelloWorld Person
2.变量名和方法名的首字母小写
eg int i int j int furColor
main catchMouse
3.运用驼峰标识
eg furColor HelloWorld
→名字多个字母构成，首单词字母大写，后面每个单词首字母都大写，像驼峰

内存调用分析例题
class BirthDate{
private int day;
private int month;
private int year;
public BirthDate(int d, int m, int y){
day = d;
month = m;
year = y;
}
public void setDay(int d ){
day = d;
}
public void setMonth(int m){
month = m;
}
public void setYear(int y){
year = y;
}
public int getDay(){
return month;
}
public int getMonth(){
return month;
}
public int getYear(){
return year;
}
public void display(){
System.out.println
(day + "-" + month + "-" + year);
}
}
public class Test{
public static void main (String args []){
Test test = new Test();
int date = 9;
BirthDate d1= new BirthDate(7,7,1970);
BirthDate d2= new BirthDate(1,1,2000);
test.change1(date);
test.change2(d1);
test.change3(d2);
System.out.println("date=" + date);
d1.display();
d2.display();
}
public void change1(int i){
i= 1234;
}
public void change2(BirthDate b){
b = new BirthDate(22,2,2004);
}
public void change3(BirthDate b){
b.setDay(22);
}
}

public class TOF{
public static void main(String args[]){
int i = 1 , j = 2;
boolean flag1,flag2;
flag1 = (i>3)&&((i+j)>5);
System.out.println(flag1);
flag2 = (i<2)||((i+j)<6);
System.out.println(flag2);
}
}

1+3+5+7+9+...+99 的写法
while语句
public class Add{
public static void main(String args []){
int i = 1;
int x = 0;
do {
x=x+i;
i+=2;
}
while (i<=99);
System.out.println(x);
}
}

1+3+5+7+9+...+99 的写法
while语句
public class Add{
public static void main(String args []){
int i = 1;
int x = 0;
do {
x=x+i;
i+=2;
}
while (i<=99);
System.out.println(x);
}
}

1+3+5+7+9+...+99 的写法
for语句
for语句1
public class AddFor1{
public static void main (String args []){
long f=0;
long result=0;
for (int i = 1 ; i <= 99 ; i+=2){
result=f+ i;
f=result;
}
System.out.println("result = " + result);
}
}
for语句 2
public class AddFor2{
public static void main (String args []){
long result=0;
for (int i = 1 ; i <= 99 ; i+=2){
result=result+ i;
}
System.out.println("result = " + result);
}
}