錯誤：無法找到或加載主類車輛。車輛

Question

當談到我缺乏Java技能時，我仍然處於HelloWorld。我無法理解這是爲了挽救我的生命。我正在寫一個覆蓋方法？在我開始嘗試完成其餘的課程之前，我剛剛開始使用我的學校提供​​的代碼，而且我已經發現了一些我甚至無法想到如何糾正的錯誤。任何幫助都將不勝感激。我只是希望這個錯誤消失，所以我可以創造一些新的:) 下面是代碼：

public class Vehicle 
public static void main (String [] args)} 
{ 
private boolean moving; // whether or not the vehicle 
private double speed; 
private char bearing; 
('N','E','S', or 'W') 
public Vehicle(){ // Vehicle class no-arg constructor 
    moving = false; // assume not moving 
    speed = 0.0; // not moving 
    bearing = 'N'; // assume 'N'orth 
    System.out.println("Created a vehicle (no-arg)"); 
} 
public Vehicle (double initialSpeed) // Vehicle 1-arg constructor 
    bearing = 'W'; 
    speed = initialSpeed; 
    if (speed > 0.0) 
    { 
     moving = true; 
    } 
    System.out.println("Created a vehicle (1-arg)"); 
public Vehicle (double initialSpeed, char initialBearing) // Vehicle 2-arg constructor 
    bearing = initialBearing; 
    speed = initialSpeed; 
    if (speed > 0.0){ 
     moving = true; 
    } 
    System.out.println("Created a vehicle (2-arg)"); 
public void start(double initialSpeed, char initialBearing){ 
    moving = true; 
    if (initialSpeed >= 5.0 && initialSpeed <= 20.0){ 
     speed = initialSpeed; // valid expected range 
    } else if (initialSpeed >= 0.0 && initialSpeed < 5.0){ 
     speed = 5.0; // minimum 
    } else if (initialSpeed < 0.0){ 
     speed = 0.0; // assume no movement 
     moving = false; 
    } else if (initialSpeed > 20.0){ 
     speed = 20.0; // maximum allowed 
    } 
    switch(initialBearing){ 
    case 'N': 
     bearing = initialBearing; 
     break; 
    case 'E': 
     bearing = initialBearing; 
     break; 
    case 'S': 
     bearing = initialBearing; 
     break; 
    case 'W': 
     bearing = initialBearing; 
    default: 
System.out.println("invalid bearing " + 
    initialBearing + 
    " set to N"); // additional user notification 
    bearing = 'N'; 
} 
public double getSpeed() { // get and return current speed in mph 
    return speed; 
} 
public void setSpeed(double newSpeed){ // set new speed in mph 
    speed = newSpeed; 
} 
    /** 
    * 
    * @return 
    */ 
public char getBearing(){ 
    return bearing; 
} 
public void speedUp(double mphSteps, int numSteps){ 
    int counter = 0; 
    while (counter < numSteps) 
    speed += mphSteps; 
    System.out.println("counter= " + counter + ", " + 
    this.toString()); 
    counter++; 
} 
public String toString(){ 
    return "From toString(): speed= " + getSpeed() + 
    " mph and bearing= " + getBearing(); 
} 
} 
public class Car extends Vehicle{ 
    private String color; 
    private int doors; 
    private double hp; 
    public Car(String carColor, int numDoors, 
    double horsePower, double 
    startingSpeed) 
{ 
super(startingSpeed); 
color = carColor; 
doors = numDoors; 
hp = horsePower; 
System.out.println("Created a car"); 
} 
public String getColor() 
{ 
return color; 
} 
public int getDoors() 
{ 
return doors; 
} 
public double getHp() 
{ 
return hp; 
} 
public String toString() 
{ 
return "From Car toString(): color= " + getColor() + 
" doors= " + getDoors() + 
" hp= " + getHp() + 
" speed= " + getSpeed() + 
" mph and bearing= " + getBearing();} 
} 
public class TestCar2 
{ 
public static void main(String[] args) 
{ 
Car myCar2 = new Car("blue", 4, 300., 10.0); 
System.out.println(myCar2.toString()); 
myCar2.speedUp(5.0, 2); 
} 
} 

請請，謝謝您的幫助！

Answer 1

public class Vehicle 

public static void main (String [] args)} // this is totally wrong 
    // This not compile at least 
{ 

實際上你使用的是parenthesis（{}）是完全錯誤的。以下結構應該跟着你。我猜測你沒有使用IDE來編寫代碼。我建議你使用IDE來做代碼。

public class MyClass{ 

public static void main(String[] args){ 
    // main method 
} 
// some other method 

} 

Answer 2

首先你不能在一個文件中有兩個公共類！

其次，你的括號完全不匹配。

public class Vehicle 
public static void main (String [] args)} 
{ 

類有它自己的作用域，main（）函數有它自己的作用域。因此，將您的代碼更改爲

public class Vehicle { 
public static void main (String [] args) { //your code} 
} 

您的多個arg構造函數沒有正確的括號。

public Vehicle (double initialSpeed) // Vehicle 1-arg constructor 
    bearing = 'W'; 
    speed = initialSpeed; 
    if (speed > 0.0) 
    { 
     moving = true; 
    } 
    System.out.println("Created a vehicle (1-arg)"); 

將其更改爲

public Vehicle (double initialSpeed) { // Vehicle 1-arg constructor 
    bearing = 'W'; 
    speed = initialSpeed; 
    if (speed > 0.0) 
    { 
     moving = true; 
    } 
    System.out.println("Created a vehicle (1-arg)"); 
} 

最後你的switch語句，你需要把斷在所有情況下（除了默認） 變化

case 'W': 
bearing = initialBearing; 

到

case 'W': 
bearing = initialBearing; 
break; 

如果你對於java和學習基礎知識都是新手，我建議使用Eclipse，Netbeans或Intellij IDEA之類的IDE。谷歌他們找到更多的信息。