在要求用户输入变量后，无法解析为变量 [英] Cannot be resolved to a variable, after asking user to input variable

问题描述

这可能是显而易见的事情，但是当我试图强制用户继续输入值直到他输入有效值时，我得到一个错误，该变量无法解析。

It's probably something obvious, but when I'm trying to force the user to keep entering a value until he enters a valid value, I get an error that the variable cannot be resolved.

然后，如果我事先声明它，我会收到错误的重复值。

Then if I declare it beforehand I get an error saying duplicate value.

do {
    float x = Float.parseFloat(javax.swing.JOptionPane.showInputDialog("Enter 1");
} while (x != 1);

编译器不应该先执行 do 语句，然后再担心而？

Isn't the compiler supposed to execute the do statement first, before worrying about the while?

推荐答案

在循环之前声明 x ，使其范围更加如下所示：

declare x before the loop, make its scope more broder like below :

float x = 0.0f;
do {
    x = Float.parseFloat(javax.swing.JOptionPane.showInputDialog("Enter 1"); 
} while (x != 1);

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