Question

我的问题是我有一个进入意外无限循环的方法，我无法确定原因。该方法应该从用户获取输入并将其分配给三个不同的对象。但是，在循环运行两次并要求用户输入第三个对象的名称后，程序无限循环。我应该指出，我仍然是相对较新的java并且学习编程。

以下是代码（我已经开始发表评论!!!!我相信这与问题有关）：

private void readInput()    
//This method accepts input from the user about product data and sets the values of 
//product1, product2 and product3
//Also validates all input so as not to crash the program if the user enters incorrect data
{       
    String name;        
    int demandRate, productChoice=1; 
    final int MAXPRODUCTS=3;
    double setupCost, unitCost, inventoryCost, sellingPrice;

    Scanner console = new Scanner(System.in);

    while (productChoice <= MAXPRODUCTS)    
    //A loop that makes the user enter data for all three products and then stops after the third entry
    {                                      
        System.out.println("Please enter the product's name: ");
        name = console.next();       
        matesStore.isAProduct(name);     // checks whether the product name the user has entered is unique.
        while (matesStore.isAProduct(name))  
        //If a name that has already been entered is found, the user will be asked to reenter the name
        {
            System.out.println("That name is already in use. Please choose another: "); 
            name = console.next();
        }
        while (!matesStore.isAProduct(name))
        //If a name has not been used, the name is added to the product
        {
            matesStore.addProduct(name); //!!!!I suspect the problem is this line.
        }            
        System.out.println("Please enter the product's demand rate: ");
        demandRate = console.nextInt();                         
        System.out.println("Please enter the product's setup cost: ");
        setupCost = console.nextDouble();
        System.out.println("Please enter the product's unit cost: ");
        unitCost = console.nextDouble();
        System.out.println("Please enter the product's inventory cost: ");
        inventoryCost = console.nextDouble();
        System.out.println("Please enter the product's selling price: ");
        sellingPrice = console.nextDouble();
        matesStore.addData(productChoice, demandRate, setupCost, unitCost, inventoryCost, sellingPrice);    //Uses the method from the Store class to set the data values for the products.
        productChoice++;        
    }
    while (productChoice > MAXPRODUCTS)
    {
        System.out.println("The list is now full.");
        continueOption();
    }         
}//End of Method and Interface class

这是Store类的方法：

public boolean isAProduct(String product)
//Returns true if a name has been found otherwise returns false
{
    boolean found = false;
    int counter = 0;

    while (!found && (counter < MAXNUMBEROFPRODUCTS))
    {
        if (product.equalsIgnoreCase(product1.getName()))
        {
            found = true;
        }
        else if (product.equalsIgnoreCase(product2.getName()))
        {
            found = true;                 
        }
        else 
        {
            counter++;
        }            
    }        

    return found;
}//End of method

public void addProduct(String product)
//If isAProduct() returns false then the product name 
//entered by the user is stored in product1, product2 and product3 respectively

//!!!!I think this is where the problem originates but can't figure out why
{   
    if (numberOfProducts == 0) 
    //!!!!numberOfProducts has been declared as private int numberOfProducts=0;
    //I tried declaring numberOfProducts as a variable within addProduct()
    //but that just set the value to 0 each time and so only the name for product1 was set
    {
        product1.setName(product);
        numberOfProducts++;
    }
    else if (numberOfProducts == 1)
    {
        product2.setName(product);
        numberOfProducts++;
    }
    else if (numberOfProducts == 2)
    {                
        product3.setName(product);
    }            
    else
    {
        System.exit(0);
    }
}

非常感谢任何帮助或建议：）

干杯

Answer 1

while (!matesStore.isAProduct(name))
        //If a name has not been used, the name is added to the product
        {
            matesStore.addProduct(name); //!!!!I suspect the problem is this line.
        }

第三个产品是无限循环的原因是因为你应该使用If作为这个语句，同时也可以工作，但是你看到有一个错误是由于你的方法addProduct。如果你改为如果它不是一个无限循环，那么你的产品3将被窃听。

public boolean isAProduct(String product)
//Returns true if a name has been found otherwise returns false
{
    boolean found = false;
    int counter = 0;

    while (!found && (counter < MAXNUMBEROFPRODUCTS))
    {
        if (product.equalsIgnoreCase(product1.getName()))
        {
            found = true;
        }
        else if (product.equalsIgnoreCase(product2.getName()))
        {
            found = true;                 
        }
        else 
        {
            counter++;
        }            
    }        

    return found;
}//End of method

注意到您没有检查product3，因此在搜索第3个产品名称时它将始终返回false。

！matesStore.isAProduct（name）=！false = true

堇菜!!你去的时候（真的），一个无限循环！

通过在isAProduct（）方法中实现product3.getName（）来修复。

您的代码很乱，您应该为产品使用数组，并且可以使用数组进行更好的搜索。

public boolean isAProduct(String product)
//Returns true if a name has been found otherwise returns false
{
    boolean found = false;
    int counter = 0;

    while (!found && (counter < MAXNUMBEROFPRODUCTS))
    {
        if (product.equalsIgnoreCase(product1.getName()))
        {
            found = true;
        }
        else if (product.equalsIgnoreCase(product2.getName()))
        {
            found = true;                 
        }
        else if (product.equalsIgnoreCase(product3.getName()))
        {
            found = true;                 
        }
        else 
        {
            counter++;
        }            
    }        

    return found;
}//End of method

Java意外无限循环

1 个答案: