java怎么实现“01”+”1“=“02”
时间: 2023-11-05 12:02:27 浏览: 28
可以使用字符串补全的方式实现:
1. 将两个字符串补全到相同长度,可以使用String.format方法,例如:
```
String s1 = "01";
String s2 = "1";
int len = Math.max(s1.length(), s2.length());
s1 = String.format("%" + len + "s", s1).replace(' ', '0');
s2 = String.format("%" + len + "s", s2).replace(' ', '0');
```
2. 将两个字符串转换为数字,相加后再转换回字符串,例如:
```
int num1 = Integer.parseInt(s1);
int num2 = Integer.parseInt(s2);
int sum = num1 + num2;
String result = String.format("%0" + len + "d", sum);
```
两种方法都可以实现“01” ”1“=“02”的效果。
相关问题
java CRC 校验x16 + x12 + x2 + 1实现
以下是Java实现CRC校验x16 + x12 + x2 + 1的代码示例:
```java
public class Crc16 {
private static final int POLY = 0x1021; // x16 + x12 + x2 + 1
public static int crc(byte[] bytes) {
int crc = 0xFFFF;
for (byte b : bytes) {
crc ^= (b & 0xFF) << 8;
for (int i = 0; i < 8; i++) {
if ((crc & 0x8000) != 0) {
crc = (crc << 1) ^ POLY;
} else {
crc <<= 1;
}
}
}
return crc & 0xFFFF;
}
}
```
使用方法:
```java
byte[] bytes = {0x01, 0x02, 0x03, 0x04};
int crc = Crc16.crc(bytes);
System.out.println("CRC16校验结果:" + Integer.toHexString(crc));
```
其中,`bytes`是需要进行CRC校验的数据,`crc`是计算得出的校验结果。注意,最终的校验结果需要转换为16进制字符串输出。
java实现rip
以下是一个简单的Java实现RIP的示例:
```
import java.io.IOException;
import java.net.*;
import java.util.*;
public class RIP {
private static final int RIP_PORT = 520; //RIP协议使用的端口号
private static final int MAX_ROUTES = 100; //最大路由数
private static class Route {
String prefix; //网络前缀
String nexthop; //下一跳地址
int metric; //距离
}
public static void main(String[] args) {
List<Route> routes = new ArrayList<>(); //路由表
routes.add(new Route() {{ prefix = "10.0.0.0"; nexthop = "192.168.0.1"; metric = 1; }}); //添加初始路由
try {
DatagramSocket sock = new DatagramSocket(RIP_PORT); //创建套接字并绑定端口号
byte[] buf = new byte[1024];
DatagramPacket packet = new DatagramPacket(buf, buf.length);
while (true) {
sock.receive(packet); //接收RIP报文
byte[] data = packet.getData();
int len = packet.getLength();
if (data[0] == 0x01) { //Command字段:请求
InetAddress address = packet.getAddress();
int port = packet.getPort();
for (Route route : routes) {
//构造RIP响应报文
byte[] response = new byte[20];
response[0] = 0x02; //Command字段:响应
response[1] = 0x01; //Version字段:RIPv1
response[2] = 0x00; //Unused字段:0
response[3] = 0x00; //Unused字段:0
response[4] = 0x00; //Address Family Identifier字段:IPv4
response[5] = 0x00; //Address Family Identifier字段:IPv4
response[6] = 0x00; //Route Tag字段:0
response[7] = 0x00; //Route Tag字段:0
String[] parts = route.prefix.split("\\.");
for (int i = 0; i < 4; i++) {
response[8+i] = (byte) Integer.parseInt(parts[i]); //IP地址字段
}
response[12] = 0xff; //Subnet Mask字段:255.255.255.0
response[13] = 0xff; //Subnet Mask字段:255.255.255.0
response[14] = 0xff; //Subnet Mask字段:255.255.255.0
response[15] = 0x00; //Subnet Mask字段:255.255.255.0
parts = route.nexthop.split("\\.");
for (int i = 0; i < 4; i++) {
response[16+i] = (byte) Integer.parseInt(parts[i]); //Next Hop字段
}
response[20] = (byte) route.metric; //Metric字段
//发送RIP响应报文
DatagramPacket responsePacket = new DatagramPacket(response, response.length, address, port);
sock.send(responsePacket);
}
} else if (data[0] == 0x02) { //Command字段:响应
for (int i = 0; i < len-4; i += 20) {
Route route = new Route();
StringBuilder sb = new StringBuilder();
for (int j = 0; j < 4; j++) {
sb.append(data[i+8+j] & 0xff).append("."); //解析IP地址
}
sb.setLength(sb.length()-1);
route.prefix = sb.toString();
sb = new StringBuilder();
for (int j = 0; j < 4; j++) {
sb.append(data[i+16+j] & 0xff).append("."); //解析Next Hop地址
}
sb.setLength(sb.length()-1);
route.nexthop = sb.toString();
route.metric = data[i+20]; //解析Metric值
routes.add(route); //添加到路由表中
}
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
```
这只是一个简单的示例,实际上RIP协议的实现还需要考虑很多细节和安全问题。
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