Question

我在尝试在命令行上运行程序时遇到了一些问题。我在NetBeansProjects目录中创建了2个目录。第一个叫做foodpackage，第二个是foodpackage的子目录，叫做fruitpackage。在fruitpackage中，我有两个名为Food.java和FoodMain.java的java文件。 Food.java 中的代码如下所示：

package foodpackage.fruitpackage;

public class Food{

// declare instance variabels
private String foodVarieties;
private String foodList;

// returns foodVarieties
public String getFoodVarieties(){
return foodVarieties;
}

// sets foodVarieties
public void setFoodVarieties(String temp){
foodVarieties = temp;
}

// returns foodList
public String getFoodList(){
return foodList;
}

// sets foodList
public void setFoodList(String temp){
foodList = temp;
}
}

FoodMain.java 的代码如下所示：

import foodpackage.fruitpackage.*;

public class FoodMain{

public static void main(String args[]){

// create an object instance of Food class
Food t = new Food();

// set the foodVarieties
t.setFoodVarieties("Food varieties: Vegetables and Meat");

// set the foodList
t.setFoodList("Food list: chicken, lettuce, and broccoli");

// print the foodVarieties
System.out.println(t.getFoodVarieties());

// print the foodList
System.out.println(t.getFoodList());
}
}

我在命令行上运行它，如下所示：

cd /Users/timothylee/NetBeansProjects
javac -cp . foodpackage/fruitpackage/*.java
java -classpath . foodpackage/fruitpackage.FoodMain

当我跑这个时，我得到了错误

Exception in thread "main" java.lang.NoClassDefFoundError: foodpackage/fruitpackage/FoodMain (wrong name: FoodMain)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

愿任何人帮我解决此错误吗？谢谢。

Answer 1

使用+代替=来连接Strings

System.out.println("ID: " + annaID.getStudentID());

Answer 2

您的专线目前是：

System.out.println("ID: " = annaID.getStudentID());

=不是您正在寻找的运营商。

System.out.println("ID: " + annaID.getStudentID());

这会将String与annaID.getStudentID()

返回的整数连接起来

Answer 3

执行此操作时：

System.out.println("ID: " = annaID.getStudentID());

您正在尝试将int分配给字符串，这很糟糕。请改用+运算符：

System.out.println("ID: " + annaID.getStudentID());

Answer 4

检查您的代码...按照您提供的图像，看起来您在system.out.println语句中键入了“=”而不是“+”

java在命令行上

4 个答案: