Java编译器返回错误：找不到符号，即使该符号已定义。

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英文:

Java compiler returning error: cannot find symbol even though the symbol is defined

问题

以下是翻译好的部分：

我是 Java 的新手，仍在努力学习基础知识，我猜我可能犯了一个非常简单的错误。我试图创建一个代码，其中两个 SavingsAccount 类的对象会按月增加利息。这是我编写的代码：

class SavingsAccount {
    
    // 主函数
    public static void main(String args[]) {
        SavingsAccount saver1 = new SavingsAccount(2000.0);
        SavingsAccount saver2 = new SavingsAccount(3000.0);
        SavingsAccount.modifyInterestRate(0.04f);

        System.out.println("S1: " + saver1);
        System.out.println("S2: " + saver2);

        SavingsAccount.modifyInterestRate(0.05f);
        System.out.println("S1: " + saver1);
        System.out.println("S2: " + saver2);
    }
    // 主函数结束
    
    static double annualInterestRate;
    private double savingsBalance;
    
    public SavingsAccount(double balance) {
        savingsBalance = balance;
    }

    public double calculateMonthlyInterest() {
        return (savingsBalance * annualInterestRate) / 12;
    }
    
    public static void modifyInterestRate(double rate) {
        annualInterestRate = rate;
    }
    
    public double getAnnualInterestRate() {
        return annualInterestRate;
    }
    
    public double getSavingsBalance() {
        return savingsBalance;
    }
}

当我尝试运行代码时，出现以下错误：

SavingsAccount.java:29: error: cannot find symbol
                SavingsAccount saver1 = new SavingsAccount(2000.0);
                ^
  symbol:   class SavingsAccount
  location: class SavingsAccount
SavingsAccount.java:29: error: cannot find symbol
                SavingsAccount saver1 = new SavingsAccount(2000.0);
                                            ^
  symbol:   class SavingsAccount
  location: class SavingsAccount
SavingsAccount.java:30: error: cannot find symbol
                SavingsAccount saver2 = new SavingsAccount(3000.0);
                ^
  symbol:   class SavingsAccount
  location: class SavingsAccount
SavingsAccount.java:30: error: cannot find symbol
                SavingsAccount saver2 = new SavingsAccount(3000.0);
                                            ^
  symbol:   class SavingsAccount
  location: class SavingsAccount
SavingsAccount.java:31: error: cannot find symbol
                SavingsAccount.modifyInterestRate(0.04f);
                ^
  symbol:   variable SavingsAccount
  location: class SavingsAccount
SavingsAccount.java:36: error: cannot find symbol
                SavingsAccount.modifyInterestRate(0.05f);
                ^
  symbol:   variable SavingsAccount
  location: class SavingsAccount
6 errors

如果有人能帮助我解决这个问题，我将非常感激。谢谢！

英文:

I am new to java and I am still trying to learn the basics, I'm guessing I've probably made a very simple error. I am trying to create a code where two objects of the class savingsAccount are incremented by a monthly interest. Here is the code that I wrote:

class SavingsAccount {


	//main
	public static void main(String args[]){
		savingsAccount saver1 = new savingsAccount(2000.0);
		savingsAccount saver2 = new savingsAccount(3000.0);
		savingsAccount.modifyAnnualInterestRate(0.04f);

		System.out.println("S1: " + saver1);
		System.out.println("S2: " + saver2);

		savingsAccount.modifyAnnualInterestRate(0.05f);
		System.out.println("S1: " + saver1);
		System.out.println("S2: " + saver2);
	}
	//end main
	
	
	static double annualInterestRate;
	private double savingsBalance;
	
	public void savingsAccount(double balance){
		savingsBalance = balance;
	}

	public double calculateMonthlyInterest(){
		return (savingsBalance * annualInterestRate)/12;
	}
	
	public static void modifyInterestRate(double rate){
		annualInterestRate = rate;
	}
	
	public double getAnnualInterestRate(){
		return annualInterestRate;
	}
	
	public double getSavingsBalance(){
		return savingsBalance;
	}

}

When I attempt to run the code, these errors are returned:

SavingsAccount.java:29: error: cannot find symbol
                savingsAccount saver1 = new savingsAccount(2000.0);
                ^
  symbol:   class savingsAccount
  location: class SavingsAccount
SavingsAccount.java:29: error: cannot find symbol
                savingsAccount saver1 = new savingsAccount(2000.0);
                                            ^
  symbol:   class savingsAccount
  location: class SavingsAccount
SavingsAccount.java:30: error: cannot find symbol
                savingsAccount saver2 = new savingsAccount(3000.0);
                ^
  symbol:   class savingsAccount
  location: class SavingsAccount
SavingsAccount.java:30: error: cannot find symbol
                savingsAccount saver2 = new savingsAccount(3000.0);
                                            ^
  symbol:   class savingsAccount
  location: class SavingsAccount
SavingsAccount.java:31: error: cannot find symbol
                savingsAccount.modifyAnnualInterestRate(0.04f);
                ^
  symbol:   variable savingsAccount
  location: class SavingsAccount
SavingsAccount.java:36: error: cannot find symbol
                savingsAccount.modifyAnnualInterestRate(0.05f);
                ^
  symbol:   variable savingsAccount
  location: class SavingsAccount
6 errors

If anyone could help me with this, I would be very grateful. Thank you!

答案1

得分: 1

你没有为这个类创建构造函数。

public class SavingsAccount {

//主函数
public static void main(String args[]) {
    SavingsAccount saver1 = new SavingsAccount(2000.0);
    SavingsAccount saver2 = new SavingsAccount(3000.0);
    saver1.modifyInterestRate(0.04f);
    saver1.calculateMonthlyInterest();
    System.out.println("S1：" + saver1.calculateMonthlyInterest());
    System.out.println("S2：" + saver2.calculateMonthlyInterest());

    saver1.modifyInterestRate(0.05f);
    saver1.calculateMonthlyInterest();
    System.out.println("S1：" + saver1.calculateMonthlyInterest());
    System.out.println("S2：" + saver2.calculateMonthlyInterest());
}
//结束主函数

private double annualInterestRate;
private double savingsBalance;

//构造函数
public SavingsAccount(double balance) {
    savingsBalance = balance;
}

public double calculateMonthlyInterest() {
    return (savingsBalance * annualInterestRate) / 12;
}

public void modifyInterestRate(double rate) {
    annualInterestRate = rate;
}

public double getAnnualInterestRate() {
    return annualInterestRate;
}

}

我认为你正在学习面向对象编程。我为你提供了一个更好的示例供你学习。

public class Main {

public static void main(String[] args) {

//为SavingsAccount创建两个实例，并将savingsBalance传递给构造函数
SavingsAccount saver1 = new SavingsAccount(2000.0);
SavingsAccount saver2 = new SavingsAccount(3000.0);
//设置年利率的值
saver1.setAnnualInterestRate(0.5);
saver2.setAnnualInterestRate(0.7);

//计算月利息并打印出来
System.out.println("S1：" + saver1.calculateMonthlyInterest());
System.out.println("S2：" + saver2.calculateMonthlyInterest());

//更改利率
saver1.setAnnualInterestRate(0.1);
saver2.setAnnualInterestRate(0.2);
System.out.println("S1：" + saver1.calculateMonthlyInterest());
System.out.println("S2：" + saver2.calculateMonthlyInterest());
}

//为了更好的结构，创建一个独立的类
static class SavingsAccount {

private double savingsBalance = 0;

private double annualInterestRate = 0;

//构造函数
public SavingsAccount(double savingsBalance) {
    this.savingsBalance = savingsBalance;
}

//计算月利息的函数
public double calculateMonthlyInterest() {
    return (savingsBalance * annualInterestRate) / 12f;
}

//类值的getter和setter
public double getAnnualInterestRate() {
    return annualInterestRate;
}

public void setAnnualInterestRate(double annualInterestRate) {
    this.annualInterestRate = annualInterestRate;
}

public double getSavingsBalance() {
    return savingsBalance;
}

public void setSavingsBalance(double savingsBalance) {
    this.savingsBalance = savingsBalance;
}

}

}
英文:

You didn't create a constructor for the class.

public class SavingsAccount {
//main
public static void main(String args[]){
SavingsAccount saver1 = new SavingsAccount(2000.0);
SavingsAccount saver2 = new SavingsAccount(3000.0);
saver1.modifyInterestRate(0.04f);
saver1.calculateMonthlyInterest();
System.out.println("S1: " + saver1.calculateMonthlyInterest());
System.out.println("S2: " + saver2.calculateMonthlyInterest());
saver1.modifyInterestRate(0.05f);
saver1.calculateMonthlyInterest();
System.out.println("S1: " + saver1.calculateMonthlyInterest());
System.out.println("S2: " + saver2.calculateMonthlyInterest());
}
//end main
private double annualInterestRate;
private double savingsBalance;
//Constructor
public SavingsAccount(double balance){
savingsBalance = balance;
}
public double calculateMonthlyInterest(){
return (savingsBalance * annualInterestRate)/12;
}
public void modifyInterestRate(double rate){
annualInterestRate = rate;
}
public double getAnnualInterestRate(){
return annualInterestRate;
}
}

I think you are learning oop. I placed a better example for your study.

public class Main {
public static void main(String[] args) {
//Create two instances for SavingsAccount and pass the savingsBalance to constructor
SavingsAccount saver1 = new SavingsAccount(2000.0);
SavingsAccount saver2 = new SavingsAccount(3000.0);
//Set the value rate of the AnnualInterestRate
saver1.setAnnualInterestRate(0.5);
saver2.setAnnualInterestRate(0.7);
//calculate the Monthly Interest and print it out
System.out.println("S1: " + saver1.calculateMonthlyInterest());
System.out.println("S2: " + saver2.calculateMonthlyInterest());
//Change the rate
saver1.setAnnualInterestRate(0.1);
saver2.setAnnualInterestRate(0.2);
System.out.println("S1: " + saver1.calculateMonthlyInterest());
System.out.println("S2: " + saver2.calculateMonthlyInterest());
}
//Create a separated class for a better structure
static class SavingsAccount {
private double savingsBalance = 0;
private double annualInterestRate = 0;
//Constructor
public SavingsAccount(double savingsBalance){
this.savingsBalance = savingsBalance;
}
//Function for calculat the eMonthly Interest
public double calculateMonthlyInterest(){
return (savingsBalance * annualInterestRate)/12f;
}
//Getter setter for the class value
public double getAnnualInterestRate(){
return annualInterestRate;
}
public void setAnnualInterestRate(double annualInterestRate){
this.annualInterestRate = annualInterestRate;
}
public double getSavingsBalance(){
return savingsBalance ;
}
public void setSavingsBalance(double savingsBalance){
this.savingsBalance = savingsBalance;
}
}
}

答案2

得分: 0

class SavingsAccount {

    // 主方法
    public static void main(String args[]){
        SavingsAccount saver1 = new SavingsAccount();
        SavingsAccount saver2 = new SavingsAccount();

        saver1.savingsAccount(2000.0);
        saver2.savingsAccount(3000.0);

        SavingsAccount.modifyInterestRate(0.04);

        System.out.println("S1: " + saver1.calculateMonthlyInterest());
        System.out.println("S2: " + saver2.calculateMonthlyInterest());

        SavingsAccount.modifyInterestRate(0.05);
        System.out.println("S1: " + saver1.calculateMonthlyInterest());
        System.out.println("S2: " + saver2.calculateMonthlyInterest());
    }
    // 结束主方法

    static double annualInterestRate;
    private double savingsBalance;

    public void savingsAccount(double balance){
        savingsBalance = balance;
    }

    public double calculateMonthlyInterest(){
        return (savingsBalance * annualInterestRate)/12;
    }

    public static void modifyInterestRate(double rate){
        annualInterestRate = rate;
    }

    public double getAnnualInterestRate(){
        return annualInterestRate;
    }

    public double getSavingsBalance(){
        return savingsBalance;
    }
}
英文:

I don't know what you are trying to do but here is your compilable code

class SavingsAccount {
//main
public static void main(String args[]){
SavingsAccount saver1 = new SavingsAccount();
SavingsAccount saver2 = new SavingsAccount();
saver1.savingsAccount(2000.0);
saver2.savingsAccount(3000.0);
SavingsAccount.modifyInterestRate(0.04);
System.out.println("S1: " + saver1.calculateMonthlyInterest());
System.out.println("S2: " + saver2.calculateMonthlyInterest());
SavingsAccount.modifyInterestRate(0.05);
System.out.println("S1: " + saver1.calculateMonthlyInterest());
System.out.println("S2: " + saver2.calculateMonthlyInterest());
}
//end main
static double annualInterestRate;
private double savingsBalance;
public void savingsAccount(double balance){
savingsBalance = balance;
}
public double calculateMonthlyInterest(){
return (savingsBalance * annualInterestRate)/12;
}
public static void modifyInterestRate(double rate){
annualInterestRate = rate;
}
public double getAnnualInterestRate(){
return annualInterestRate;
}
public double getSavingsBalance(){
return savingsBalance;
}

}

答案3

得分: 0

你的类名是SavingsAccount，但是当你创建对象实例时，你写成了savingsAccount；

Java是区分大小写的语言，所以你需要将savingsAccount更改为SavingsAccount。

并且你缺少了一个构造函数：

public SavingsAccount(double savingsBalance){
      this.savingsBalance = savingsBalance;
}
英文:

Your class name is SavingsAccount, but when you create an object instance, you write savingsAccount;

Java is a case-sensitive language, so you need to change savingsAccount to SavingsAccount

And you are missing a constructor:

public SavingsAccount(double savingsBalance){
      this. savingsBalance = savingsBalance;
}

答案4

得分: -1

Java是一种区分大小写的语言。创建对象时，您需要使用与类名相同的名称。在您的情况下，您必须使用

SavingsAccount saver1 = new SavingsAccount(2000.0);
英文:

Java is a Case-sensitive language. When creating objects you need to use the same name as the class name. In your case you have to use

SavingsAccount saver1 = new SavingsAccount(2000.0);

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  • 本文由 发表于 2020年10月17日 02:26:58
  • 转载请务必保留本文链接：https://go.coder-hub.com/64394534.html
  • java
  • methods
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