错误：无法找到符号

Question

我试图让我的世界国防部，但我不知道这错误了：

src\minecraft\net\minecraft\src\Packet2ClientProtocol.java:35: error: cannot fin 
d symbol 
       par1DataOutputStream.writeByte(this.protocolVersion); 
              ^

symbol: variable protocolVersion 
src\minecraft\net\minecraft\src\Packet2ClientProtocol.java:36: error: cannot fin 
d symbol 
     writeString(this.serverHost, par1DataOutputStream); 
        ^

symbol: variable serverHost 
src\minecraft\net\minecraft\src\Packet2ClientProtocol.java:37: error: cannot fin 
d symbol 
     par1DataOutputStream.writeInt(this.serverPort); 
            ^

symbol: variable serverPort 
src\minecraft\net\minecraft\src\Packet2ClientProtocol.java:38: error: cannot fin 
d symbol 
      writeString(this.username, par1DataOutputStream); 
          ^

symbol: variable username 
src\minecraft\net\minecraft\src\Packet2ClientProtocol.java:54: error: cannot fin 
d symbol 
     return 3 + 2 * this.username.length(); 
        ^

symbol: variable username 
src\minecraft\net\minecraft\src\Packet2ClientProtocol.java:62: error: cannot fin 
d symbol 
    return this.protocolVersion; 
      ^

symbol: variable protocolVersion 
src\minecraft\net\minecraft\src\Packet2ClientProtocol.java:70: error: cannot fin 
d symbol 
    return this.username; 
      ^

这里是我的Packet2ClientProtocol.java：

package net.minecraft.src; 

import java.io.DataInputStream; 
import java.io.DataOutputStream; 
import java.io.IOException; 

public class Packet2ClientProtocol extends Packet 
{ 
    public Packet2ClientProtocol() {} 

    public void Packet2ClientProtocol(int par1, String par2Str, int par3, String par4Str) 
    { 
     int protocolVersion = par1; 
     String serverHost = par2Str; 
     int serverPort = par3; 
     String username = par4Str; 
    } 

    /** 
    * Abstract. Reads the raw packet data from the data stream. 
    */ 
    public void readPacketData(DataInputStream par1DataInputStream) throws IOException 
    { 
    int protocolVersion = par1DataInputStream.readByte(); 
     String serverHost = readString(par1DataInputStream, 255); 
     int serverPort = par1DataInputStream.readInt(); 
    String username = Info.Username; 
    } 

    /** 
    * Abstract. Writes the raw packet data to the data stream. 
    */ 
    public void writePacketData(DataOutputStream par1DataOutputStream) throws IOException 
    { 
    par1DataOutputStream.writeByte(this.protocolVersion); 
     writeString(this.serverHost, par1DataOutputStream); 
     par1DataOutputStream.writeInt(this.serverPort); 
    writeString(this.username, par1DataOutputStream); 
    } 

    /** 
    * Passes this Packet on to the NetHandler for processing. 
    */ 
    public void processPacket(NetHandler par1NetHandler) 
    { 
     par1NetHandler.handleClientProtocol(this); 
    } 

    /** 
    * Abstract. Return the size of the packet (not counting the header). 
    */ 
    public int getPacketSize() 
    { 
     return 3 + 2 * this.username.length(); 
    } 

    /** 
    * Returns the protocol version. 
    */ 
    public int getProtocolVersion() 
    { 
     return this.protocolVersion; 
    } 

    /** 
    * Returns the username. 
    */ 
    public String getUsername() 
    { 
     return this.username; 
    } 
} 

我做了什么这是错误的吗？我确信我拼写正确，我忘记了什么？

Answer 1

一个关于你试图使一个构造几个点： -

public void Packet2ClientProtocol(int par1, String par2Str, int par3, String par4Str) 
{ 
    int protocolVersion = par1; 
    String serverHost = par2Str; 
    int serverPort = par3; 
    String username = par4Str; 
} 

1. 构造函数没有任何返回类型（从那里删除void）。

2. 您尚未将参数值分配给实例变量。相反，你已经创建了一些局部变量，你当然不能在构造函数之外访问。

所以，使用this.protocolVersion会给你错误，因为你还没有声明任何具有该名称的实例变量。

你应该在你的类中声明你的变量为字段。

Answer 2

所有的变量：

int protocolVersion = par1; 
    String serverHost = par2Str; 
    int serverPort = par3; 
String username = par4Str; 

是构造函数的局部变量。让他们成为领域。