Question

java新手。按照书来练习编码。

继承我的代码：

class Motorcycle {


    //Three instance variables - make and color are strings. while a boolean refers to TRUE OR FLASE(in this case off or on)
    String make;
    String color;
    boolean engineState;

    void startEngine() {
        if (engineState == true)
            System.out.print("The engine is already on.");
        else {
            engineState = true;
            System.out.print("The engine is now on.");

        }

    void showAtts() {
        System.out.print("This motorcycle is a " + color + " " + make);
        if (engineState ==true)
            System.out.print("The engine is on.");
        else System.out.print("The engine is off.");

    }
}
}

当我编译时，我得到2个错误：

1）非法开始表达 2）;预期

我无法指出问题所在。如果有人可以指示我或暗示我，请做。

Answer 1

你的一个牙套在错误的地方。应该是：

class Motorcycle {

//Three instance variables - make and color are strings. while a boolean refers to TRUE OR FLASE(in this case off or on)
  String make;
  String color;
  boolean engineState;

  void startEngine() {
    if (engineState == true)
      System.out.print("The engine is already on.");
    else {
      engineState = true;
      System.out.print("The engine is now on.");
    }
  }
  void showAtts() {
    System.out.print("This motorcycle is a " + color + " " + make);
    if (engineState ==true)
      System.out.print("The engine is on.");
    else System.out.print("The engine is off.");
  }
}

Answer 2

方法startEngine没有关闭大括号，并且代码末尾还有另一个备用右括号

Answer 3

您已在showAtts()方法中定义了startEngine()方法。方法不能定义另一种方法。

这可能是由于错误地放置了牙箍。纠正它们。

Answer 4

class Motorcycle {

    // Three instance variables - make and color are strings. while a
    // boolean refers to TRUE OR FLASE(in this case off or on)
    String make;
    String color;
    boolean engineState;

    void startEngine() {
        if (engineState == true)
            System.out.print("The engine is already on.");
        else {
            engineState = true;
            System.out.print("The engine is now on.");

        }
    }

    void showAtts() {
        System.out.print("This motorcycle is a " + color + " " + make);
        if (engineState == true)
            System.out.print("The engine is on.");
        else
            System.out.print("The engine is off.");

    }
}

Answer 5

您正在尝试在另一个方法中定义方法：

void startEngine() {
   if (engineState == true)
        System.out.print("The engine is already on.");
   else {
       engineState = true;
        System.out.print("The engine is now on.");

   }

 void showAtts() {
   System.out.print("This motorcycle is a " + color + " " + make);
   if (engineState ==true)
       System.out.print("The engine is on.");
   else System.out.print("The engine is off.");

}
}

分开方法：

void startEngine() {
   if (engineState == true)
        System.out.print("The engine is already on.");
   else {
       engineState = true;
        System.out.print("The engine is now on.");
   }
}  // forgot this paranthesis


void showAtts() {
   System.out.print("This motorcycle is a " + color + " " + make);
   if (engineState ==true)
       System.out.print("The engine is on.");
   else System.out.print("The engine is off.");

}

Answer 6

class Motorcycle {


//Three instance variables - make and color are strings. while a boolean refers to TRUE OR FLASE(in this case off or on)
String make;
String color;
boolean engineState;

void startEngine() {
    if (engineState == true)
        System.out.print("The engine is already on.");
    else {
        engineState = true;
        System.out.print("The engine is now on.");

    }
    } //put one here

void showAtts() {
    System.out.print("This motorcycle is a " + color + " " + make);
    if (engineState ==true)
        System.out.print("The engine is on.");
    else System.out.print("The engine is off.");

}
}
// }  remove this

Answer 7

格式正确，没有错误试试这个..

public class Motorcycle {

public static void main(String[] args) {
    Motorcycle s=new Motorcycle();
    s.showAtts();
    s.startEngine();
}

//Three instance variables - make and color are strings. while a boolean refers to TRUE OR FLASE(in this case off or on)
String make;
String color;
boolean engineState;

void startEngine() {
    if (engineState == true)
        System.out.println("The engine is already on.");
    else {
        engineState = true;
        System.out.println("The engine is now on.");

    }
}
void showAtts() {
    System.out.print("This motorcycle is a " + color + " " + make);
    if (engineState ==true)
        System.out.println("The engine is on.");
    else System.out.println("The engine is off.");

}

}

编译基本java代码时出错

7 个答案: