Question

当我将字符串''''的值输入为'是'时，if语句就像是执行System.out.println一行（“请继续购物”），就好像决定的值不是“是” ）;我该怎么做才能解决这个问题？以下是问题所在的类：

 //paying for this instance of a basket
public void payBasket(double cash){
    String decision;
    double balance;
    System.out.println("You have £" +cash);
    decision = null;
    if(cash > endTotal)
    {System.out.println("You have enough money to pay for this basket");
    }
    else 
    {System.out.println("You need more money before you can pay for these items");};
    BufferedReader reader;
    reader = new BufferedReader(new InputStreamReader(System.in));
    System.out.println("Would you like to pay for this basket?");
    try{
     decision = reader.readLine();
    }
    catch (IOException ioe){
        System.out.println("an unecpected error");
    }

    if(decision == "Yes"){balance = endTotal - cash;
        System.out.println("Your current balance is " + balance);}
        else {System.out.println("Please continue shopping");
        }
}

Answer 1

要比较String对象，请使用equals(String myValue)方法，而不是==

Answer 2

要比较java中的对象，请使用.equals（）方法而不是“==”运算符

变化

if(decision == "Yes")

到

if("Yes".equals(decision))

如果你想忽略大小写使用.equalsIgnoreCase（）方法

 if("Yes".equalsIgnoreCase(decision))

Answer 3

这里 - ＆GT; if(decision == "Yes")

使用

if(descision.equals("Yes"));

Java try catch返回false变量

3 个答案: