在Java中使用赋值操作符出现错误。

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英文:

Error at using Assignment operator in java

问题

我还遇到了以下代码行的错误:“赋值的左侧必须是一个变量”

outPutArray.charAt(i)=inputArray[i]

如何解决这个问题?我尝试加入括号但没有用

(outPutArray.charAt(i))=inputArray[i]
英文:

I also the error "Left Hand Side of an Assignment must be a Variable" for following line

outPutArray.charAt(i)=inputArray[i]

how to resolve this? I have tried putting braces like but of no use

(outPutArray.charAt(i))=inputArray[i]

答案1

得分: 1

你正在尝试改变一个String对象。这是不可能的,String被设计为不可变的。你需要使用改变后内容创建一个新的String,可以使用char数组,或者其他能实际达到你最终目标的方式(即:给定一个输入String,返回一个其中一个字符改变的输出String)。

解决了这个问题后,你不能对函数的返回值进行赋值。你无法得到一个可更改的引用,进而改变某个变量的值。你得到的是一个值。关于这个问题,这个很棒的链接或许值得一读:https://stackoverflow.com/questions/40480/is-java-pass-by-reference-or-pass-by-value?rq=1。

英文:

You are trying to mutate a String object. This is not possible, String is supposed to be immutable. You have to create a new String with the changed content, use a char array instead, or something else that allows you to actually achieve what you are trying to do in the end (which is: given an input String, return an output String where one character is changed).

With that out of the way, you can't do an assignment on the return value of a function. You don't get a reference back that you can change and then some variable gets changed. You get a value back. The great https://stackoverflow.com/questions/40480/is-java-pass-by-reference-or-pass-by-value?rq=1 question is maybe a good read.

答案2

得分: 0

非常愚蠢,但格式应为:

inputArray[i] = outPutArray.charAt(i);

而不是

outPutArray.charAt(i) = inputArray[i];

将函数放在左侧意味着你正在将常量整数赋值给整数数组元素。由于整数是常量,它将失败。这就是为什么我们将变量(在你的情况下是inputArray[i])放在左边,将函数放在右边(outPutArray.charAt(i))。希望你明白!

英文:

Very silly, but the format should be:

inputArray[i] = outPutArray.charAt(i);

not

outPutArray.charAt(i) = inputArray[i] 

putting the function on the left hand side means you are assigning a constant integer to a integer array element. As the integer is constant, it will fail. This is why we put our variables(inputArray[i] in your case) on the left hand side and our functions on the right hand(outPutArray.charAt(i)). Hope you understand!

答案3

得分: 0

.charAt(i)函数返回位置i处的字符。它不会返回该索引处字符的引用。
更多详细信息请参阅此处

英文:

.charAt(i) function returns the character at position i. It does not return the reference to the character at that index.
Look at this for more details

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  • 本文由 发表于 2020年9月22日 20:56:02
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