代码只显示False，任何人都可以向我解释它有什么问题

// trying to find whether two string match after toUppercase operation

//在toUppercase操作后尝试查找两个字符串是否匹配

package testapp1;

public class TestApp1 
{
    public static void main(String[] performing_a_simple_for_loop)
    {
        String firstName = "John";
        char fname[] = {'J','O','H','N'};
        System.out.println(firstName.toUpperCase());
        String name2;
        name2 = firstName.toUpperCase();
        if(fname.equals(name2))
        {
            System.out.println("True");    
        }
        else
        {
            System.out.println("False");
        }
    }
}

2 个解决方案

#1

fname is an array, so can not be directly compared to a String

fname是一个数组,因此无法直接与String进行比较

You can do

你可以做

if(new String(fname).equals(name2))

#2

this is the reason why is always printing false

这就是为什么总是打印错误的原因

fname.equals(name2)

you are comparing a String against an array...

你正在比较一个字符串与数组...

that return false because they are not the same data type

返回false,因为它们不是相同的数据类型

imagine if I do:

想象我是否这样做:

"1".equals(1)

yes, both are holding somehow the same information, but that is not enough in java to say they are equal...

是的,两者都以某种方式持有相同的信息,但这在java中并不足以说它们是平等的......

so what you can do:??? you need to convert one type into the other...

所以你能做什么:???你需要将一种类型转换为另一种类型......

// option 1: char[] -> string
System.out.println(new String(fname).equals(firstName.toUpperCase()));

// option 2: string -> char[]
System.out.println(Arrays.equals(firstName.toUpperCase().toCharArray(), fname));

and as you see, for comparing arrays you may need the Array.equals() method

如您所见,为了比较数组,您可能需要Array.equals()方法

#1