程序清单1:
public class Test1 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();
if (n >= 1 && n <= 18){
System.out.println("少年");
} else if (n >= 19 && n <= 28) {
System.out.println("青年");
} else if (n >= 29 && n <= 55) {
System.out.println("中年");
}else{
System.out.println("老年");
}
}
}
程序清单2:
public class Test2 {
public static void main(String[] args) {
int count = 0;
for (int i = 1000; i <= 2000 ; i++) {
if( (i % 4 == 0 && i % 100 !=0) || i % 400 == 0){
System.out.print(i + " ");
count++;
}
}
System.out.println("1000 - 2000 之间所有的闰年的个数为");
System.out.println(count);//输出结果是243个
}
}
程序清单3:
public class Test3 {
public static void main(String[] args) {
for (int i = 1; i <= 9; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(i + "*" + j + "=" + i*j + " ");
}
System.out.print("\n");
}
}
}
程序清单4:
public class Test4 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int a = scanner.nextInt();
int b = scanner.nextInt();
int c = a % b;
while( c != 0 ){
a = b;
b = c;
c = a % b;
}
System.out.println(b);
}
}
程序清单5:
public class Test5 {
public static void main(String[] args) {
double sum = 0;
for (int i = 1; i <= 100 ; i++) {
int n = 1;
if(i % 2 == 0){
n = -1;
}
sum += 1.0 / (n * i);
}
System.out.println(sum);
}
}
//注意:题目给的分子都是1,编程时要换成1.0,这样才能输出小数
程序清单6:
public class Test6 {
public static void main(String[] args) {
for (int i = 1; i <= 100 ; i++) {
if( (i / 10 == 9) || (i % 10) == 9){
System.out.print(i + " ");
}
}
}
}
程序清单7:
public class Test7 {
public static void main(String[] args) {
int count = 0;
for ( int i = 1; i <= 100; i++) {
int flag = 0;
for (int j = 2; j < i; j++) {
if(i % j == 0) {
flag = 1;
break;
}
}
if(flag != 1){
System.out.println(i);
count++;
}
}
System.out.println("\n");
System.out.println("1-100之间素数的个数为:" + count);
}
}
程序清单8:
public class Test8 {
public static void main(String[] args) {
int n = 9999999;
cal(n);
}
public static void cal(int n){
for (int i = 1; i <= n; i++) {
int count = 0;
int tmp = i;
//1. 分析输入的数是几位数,若是三位数,那么count = 3
while( tmp != 0 ){
count++;
tmp/=10;
}
tmp = i;
int sum = 0;
//2. 拿到一个数的每一位数字
while(tmp != 0){
sum += Math.pow( tmp%10, count );
tmp /= 10;
}
//3. 判断!如果遵循自幂数的规则,那么就输出
if(sum == i){
System.out.println(sum);
}
}
}
}
程序清单9:
public class Test9 {
public static void main(String[] args) {
judge();
}
public static void judge() {
int count = 3;
while (count-- != 0){
System.out.println("请输入密码:");
Scanner scanner = new Scanner(System.in);
String password = scanner.nextLine();
if(password.equals("abc123")){
System.out.println("密码正确,登录成功!");
break;
}
else{
System.out.println("密码错误,你还有"+ count+ "次机会!" );
}
}
}
}
程序清单10:
public class Test10 {
public static void main(String[] args) {
int n = 11;
for (int i = 31; i >= 1 ; i = i-2) {
System.out.print(( (n>>i) & 1));
}
System.out.println();
for (int i = 30; i >= 0 ; i = i-2) {
System.out.print(( (n>>i) & 1));
}
}
}
在实现猜数字游戏之前,我们先来看一下怎么让 Java 实现随机数。
格式:
Random random = new Random();
int rand = random.nextInt(bound);
程序清单11:
public class Test11 {
public static void main(String[] args) {
Random random = new Random();
int rand = random.nextInt(50);
System.out.println(rand);
}
}
程序清单12:
public class Test12 {
public static void main(String[] args) {
Random random = new Random();
int rand = random.nextInt(50);
Scanner scanner = new Scanner(System.in);
while (true){
int input = scanner.nextInt();
if(input < rand){
System.out.println("猜小了");
}else if(input == rand){
System.out.println("猜对了");
break;
}else {
System.out.println("猜大了");
}
}
}
}
输出结果:
小伙伴们可以自己试一下,也可以将随机值显示打印出来,验证此方法。
程序清单13:
import java.util.Scanner;
public class Test13 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()){
int a = scanner.nextInt();
System.out.println("a= "+a);
int b = scanner.nextInt();
System.out.println("b= "+b);
}
}
}
//在输入界面按 ctrl + D 结束循环输入
十七最近把 C语言 顺利学完了。然后
从 C 转到 Java,从 VS 转到 IDEA,很多地方正在慢慢习惯,入门阶段,两者有一些相通的地方,比如:大多实现代码的逻辑是相似的;也有些地方很不同,比如:代码风格和一些细节处理。