“找不到符号：变速”尽管声明变量

Question

当我编译下面的代码，它说：

"error: cannot find symbol: variable max"

但我没有定义变量max ....

public class Solution { 
    public static boolean isOneEditDistance(String s, String t) { 
      if (s.length() >= t.length()) { 
        StringBuilder a = new StringBuilder (s); 
        StringBuilder b = new StringBuilder (t); 
        int max = s.length(); 
        int min = t.length(); 
      } 
      else { 
        StringBuilder a = new StringBuilder (t); 
        StringBuilder b = new StringBuilder (s); 
        int max = t.length(); 
        int min = s.length(); 
      } 

      int flag = 0; 

      if ((max-min)>1) 
        return flase; 
      else if ((max-min)==1) { 
       ..... 

Answer 1

我宁愿如下所示的代码，这也避免了因和问题B是作用域包含在if语句块。

if(s.length() < t.length()){ 
    String h = s; s = t; t = h; 
} 
// now s is not shorter than t 
int max = s.length(); 
int min = t.length(); 
StringBuilder a = new StringBuilder(s); 
StringBuilder b = new StringBuilder(t); 

Answer 2

你变量/参数的范围不正确：

If a parameter is within { } the scope is limited to within these { }

因此，将您的代码更改为此以更改范围并解决问题：

public class Solution { 
public static boolean isOneEditDistance(String s, String t) { 
int max=0; 
int min=0; 
     if (s.length() >= t.length()) { 
       StringBuilder a = new StringBuilder (s); 
       StringBuilder b = new StringBuilder (t); 
       max = s.length(); 
       min = t.length(); 
     } 
     else { 
       StringBuilder a = new StringBuilder (t); 
       StringBuilder b = new StringBuilder (s); 
       max = t.length(); 
       min = s.length(); 
     } 

     int flag = 0; 

     if ((max-min)>1) 
       return flase; 
     else if ((max-min)==1) { 

Answer 3

变量不能被看到的原因是由于变量的范围。变量能够“钻取”可见性链，但不能“挖掘”。由于该变量是在if-statemnent中声明的，因此您的变量仅在之间可见，因为它不能“挖出”。

这里是我真棒MS画图技能较差描绘我的意思大约未能范围能见度“挖出”：

Answer 4

变量已经在if (s.length() >= t.length())块被初始化。因此这些变量仅限于它。

解决方案：在条件之前初始化它们。