代碼編譯並運行在Netbeans中，但不是java命令行

Question

但是當我使用命令行運行程序時。我得到一個運行時錯誤「java.lang.NoClassDefFoundError」。我所做的只是從Netbeans複製代碼並將其粘貼到記事本文件中，然後嘗試通過命令提示符運行它。我不確定我的/做錯了什麼。任何反饋都非常感謝它！這裏是我的代碼BTW

package reader; 



import java.util.*; 
import java.io.File; 
import java.io.FileNotFoundException; 
import java.io.PrintStream; 

import java.util.Scanner; 


public class Reader{ 

public static final Scanner in = new Scanner(System.in); 
static final int adult = 0; // The index representation numbers for the total and count arrays; 
static final int child = 1; 
static final int adultMale = 2; 
static final int adultFemale = 3; 
static final int childMale = 4; 
static final int childFemale = 5; 
static final int people = 6; 
static final int family = 7; 


public static void main(String[] arg){ 

    if(arg.length > 2){ die("Too many arguments");} 
    else {System.out.println("Good");} 

String inFileName; 

    if(arg.length > 0){ inFileName = arg[0];} 
    else { 
    inFileName = "population.txt";} 

Scanner fin = openFile(inFileName); 
int[] count = new int[8]; // adults,children,male adult, female adult, male child , female child, people, family 
int[] total = new int[8]; //adults,children,male adult, female adult, male child , female child, people, family 

for( ; fin.hasNextLine(); ){ 
    String line = fin.nextLine(); 
    String error = check(line); 

    if(error != null){die(error);} 
    else{ gather(line, count, total);} 

}//loop 

for(int i = 0; i< count.length; i++){ System.out.print(count[i] + " ");} 
System.out.println(); 
for(int i = 0; i< total.length; i++){ System.out.print(total[i] + " ");} 
System.out.println(); 
System.out.println((float)count[family]/count[people]); 

fin.close(); 

String outFileName; 
if(arg.length > 1){ outFileName = arg[1];} 
else{outFileName = "output.txt";} 

PrintStream fout = outFile(outFileName); 

showCensus(fout,count,total); 

}//main 


public static void die(String message){ 

System.err.println("Error: " + message); 
System.exit(1); 

}//die 

public static Scanner openFile(String fileName){ 

Scanner inputFile = null; 
try{ 
inputFile = new Scanner(new File(fileName)); 
} 
catch(FileNotFoundException e){ die("File not found: " + fileName); 
} 

return inputFile; 

}// OpenFIle 

public static PrintStream outFile(String fileName){ 

    Scanner temp = null; 
    try{ 
    temp = new Scanner(new File(fileName)); 
    } catch(FileNotFoundException ei){ 
     PrintStream result = null; 
     try{ 
     result = new PrintStream(new File(fileName)); 
     }catch(FileNotFoundException eo){die("Can't open " + fileName);} 
     return result; 
    } 
    die("The file " + fileName + " already exists!"); 
    return null; 
} 

public static String check(String line){ 
    int change = 0; 

    String sex; 
    int age; 
    Scanner sin = new Scanner(line); 
    if(!sin.hasNext()){return null;} 
    if(sin.next().equalsIgnoreCase("Comment")){return null;} 
    Scanner sin2 = new Scanner(line); 
    while(sin2.hasNext()){ 
     change++; 
     if(change % 2 == 0){} 
     else{ 
      sex = sin2.next(); 
      if(!sex.equals("M")&& !sex.equals("F")){return "Gender must be 'M' or 'F', not " + sex;} 
      if(!sin2.hasNext()){return "No data after " + sex ;} 
      if(!sin2.hasNextInt()){return "age must be a number not " + sin2.next();} 
      age = sin2.nextInt(); 
      //System.out.print(sex + " " + age + " "); 
     } 

    } 

    System.out.println(); 

    return null; 

} 


public static void gather(String line, int[] count, int[] total){ 

    int change = 0; 
    Scanner sin = new Scanner(line); 
    if(!sin.hasNext()){return ;} 
    if(sin.next().equalsIgnoreCase("Comment")){return;} 
    Scanner sin2 = new Scanner(line); 
    while(sin2.hasNext()){ 
     change++; 
     if(change % 2 == 0){} 
     else{ 
      String sex = sin2.next(); 
      int age = sin2.nextInt(); 
      if(sex.equals("M") && age > 17){ 
       count[adultMale]++; 
       count[adult]++; 
       count[people]++; 
       total[adultMale]+= age; 
       total[adult]+= age; 
       total[people]+= age;} 
      else if(sex.equals("M") && age <= 17){ 
       count[child]++; 
       count[people]++; 
       count[childMale]++; 
       total[child]+= age; 
       total[people]+= age; 
       total[childMale]+= age;} 
      else if(sex.equals("F") && age > 17){ 
       count[adult]++; 
       count[adultFemale]++; 
       count[people]++; 
       total[adult]+= age; 
       total[adultFemale]+= age; 
       total[people]+= age;} 
      else if(sex.equals("F") && age <= 17){ 
       count[childFemale]++; 
       count[child]++; 
       count[people]++; 
       total[childFemale]+= age; 
       total[child]+= age; 
       total[people]+= age;} 
     } 
    }// while 

count[family]++; 







} 

public static void showCensus(PrintStream out, int[] count, int[] total){ 

    out.println("The Family Statistics 2013 Report"); 
    out.println(); 
    out.println("People: " + count[people] + " Average Age: " + (float)total[people]/count[people]); 
    out.println(" Adults: " + count[adult] + " Average Age: " + (float)total[adult]/count[adult]); 
    out.println("  Males: " + count[adultMale] + " Average Age: " + (float)total[adultMale]/count[adultMale]); 
    out.println("  Females: " + count[adultFemale] + " Average Age: " + (float)total[adultFemale]/count[adultFemale]); 
    out.println(" Children: " + count[child] + " Average Age: " + (float)total[child]/count[child]); 
    out.println("  Males: " + count[childMale] + " Average Age: " + (float)total[childMale]/count[childMale]); 
    out.println("  Female: " + count[childFemale] + " Average Age: " + (float)total[childFemale]/count[childFemale]); 
    out.println("Families: " + count[family] + " Average Family Size " + (float)count[family]/count[people]); 



} 





}//Reader 

Answer 1

你Reader類在reader package定義。您需要爲JVM提供適當的類路徑。創建一個名爲reader的文件夾並將您的課程放在那裏。然後在調用java時使用-classpath標誌。

c:\>javac reader\Reader.java 
c:\>java -classpath . reader.Reader