Java中的回文数程序

深碍√TFBOYSˉ_ 2023-10-05 19:48 2阅读 0赞

反向时不变的**数字**称为**回文数**。换句话说，反转数字时不影响该数字称为**回文数**。例如，回文数为121、343、555、606、999、1001、1331。在本节中，我们将创建一个**Java程序来检查数字是否为回文数。**

#### 查找回文数的算法 ####

*  获取编号，将要检查回文。
 *  通过将数字存储在某个临时变量中来创建该数字的副本。
 *  现在，反转数字。
 *  检查复印件的倒数是否相等。
 *  如果相等，那么我们有回文数。
 *  否则，该数字不是回文。

以下Java程序演示了如何使用while循环来检查给定数字是否是回文数。

**迭代法**

**文件名：** PalindromeNumberExample *。*爪哇

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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;</span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f92672;">public</span> <span style="color:#66d9ef;">class</span> <span style="color:#66d9ef;">PalindromeNumberExample</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">{ </span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span></span> 
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     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f92672;">public</span> <span style="color:#f92672;">static</span> <span style="color:#66d9ef;">void</span> <span style="color:#66d9ef;">main</span><span style="color:#f8f8f2;">(</span><span style="color:#66d9ef;">String</span><span style="color:#f8f8f2;">[</span><span style="color:#f8f8f2;">]</span> <span style="color:#f8f8f2;">args</span><span style="color:#f8f8f2;">)</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">{ </span></span></span> 
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     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#66d9ef;">int</span> <span style="color:#f8f8f2;">no</span> <span style="color:#f92672;">=</span> <span style="color:#e7a37a;">535</span><span style="color:#f8f8f2;">;</span> <span style="color:#75715e;">// To be checked for palindorme</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#66d9ef;">int</span> <span style="color:#f8f8f2;">tempVar</span> <span style="color:#f92672;">=</span> <span style="color:#f8f8f2;">no</span><span style="color:#f8f8f2;">;</span> <span style="color:#75715e;">// Creating the copy of ‘no’</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#66d9ef;">int</span> <span style="color:#f8f8f2;">sum</span> <span style="color:#f92672;">=</span> <span style="color:#e7a37a;">0</span><span style="color:#f8f8f2;">;</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">while</span><span style="color:#f8f8f2;">(</span><span style="color:#f8f8f2;">no</span> <span style="color:#f92672;">&gt;</span> <span style="color:#e7a37a;">0</span><span style="color:#f8f8f2;">)</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">{ </span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#75715e;">// reversing the number</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">sum</span> <span style="color:#f92672;">=</span> <span style="color:#66d9ef;">sum *</span> <span style="color:#e7a37a;">10</span><span style="color:#f8f8f2;">;</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">sum</span> <span style="color:#f92672;">=</span> <span style="color:#f8f8f2;">sum</span> <span style="color:#f92672;">+</span> <span style="color:#f8f8f2;">(</span><span style="color:#f8f8f2;">no</span> <span style="color:#f92672;">%</span> <span style="color:#e7a37a;">10</span><span style="color:#f8f8f2;">)</span><span style="color:#f8f8f2;">;</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">no</span> <span style="color:#f92672;">=</span> <span style="color:#f8f8f2;">no</span> <span style="color:#f92672;">/</span> <span style="color:#e7a37a;">10</span><span style="color:#f8f8f2;">;</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">}</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">if</span><span style="color:#f8f8f2;">(</span><span style="color:#f8f8f2;">tempVar</span> <span style="color:#f92672;">==</span> <span style="color:#f8f8f2;">sum</span><span style="color:#f8f8f2;">)</span></span></span> 
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     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">System</span><span style="color:#f8f8f2;">.</span><span style="color:#f8f8f2;">out</span><span style="color:#f8f8f2;">.</span><span style="color:#66d9ef;">print</span><span style="color:#f8f8f2;">(</span><span style="color:#e6db74;">"The number "</span> <span style="color:#f92672;">+</span> <span style="color:#f8f8f2;">tempVar</span> <span style="color:#f92672;">+</span><span style="color:#e6db74;">" is a palindrome number."</span><span style="color:#f8f8f2;">)</span><span style="color:#f8f8f2;">;</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">else</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">System</span><span style="color:#f8f8f2;">.</span><span style="color:#f8f8f2;">out</span><span style="color:#f8f8f2;">.</span><span style="color:#66d9ef;">print</span><span style="color:#f8f8f2;">(</span><span style="color:#e6db74;">"The number "</span> <span style="color:#f92672;">+</span> <span style="color:#f8f8f2;">tempVar</span> <span style="color:#f92672;">+</span><span style="color:#e6db74;">" is not a palindrome number."</span><span style="color:#f8f8f2;">)</span><span style="color:#f8f8f2;">;</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">}</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">}</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;</span></span> 
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**输出：**

**说明：**我们使用Java while循环来反转数字。while循环的迭代次数取决于给定数字中存在的位数。在我们的例子中是3。让我们看看程序的工作原理。

***第一次迭代：*** *sum = sum \* 10*。但是，我们将*sum*的值初始化为0；因此，我们得出*sum = 0 \* 10 = 0*。同样，我们通过将给定数字相除得到的余数*相加*来更新*总和*的值（535）。因此，我们得出*sum = 0 +（535％10）*。*总和= 0 + 5 = 5*。最后，我们将给定数字除以10，然后将商分配给该数字。*否= 535/10 = 53*。无变量的更新值为53，将在下一次迭代中使用。

***第二次迭代*****：**在第二次迭代中， *sum的*值为*5*。因此，*总和= 5 \* 10 = 50*。同样，我们将余数相加。这次的数字是53。因此，我们得出*sum = 50 +（53％10）*。*总和*变成*50 + 3 = 53*。最后，给定数字再次缩小一位，变为5。no *= 53/10 = 5*。

***第三次迭代*****：**过程相似。的*总和*为53。因此，*总和= 53 \* 10 = 530*。加完余数后，我们得到535。此外，数字变为*no = 5/10 = 0*。因为每次我们都检查while循环条件。当条件no> 0返回false时，循环终止。

**递归方法**

我们还可以使用递归方法检查回文数。

**文件名：** PalindromeNumberExample1 *。*爪哇

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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f92672;">public</span> <span style="color:#66d9ef;">class</span> <span style="color:#66d9ef;">PalindromeNumberExample1</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">{ </span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f92672;">static</span> <span style="color:#66d9ef;">boolean</span> <span style="color:#66d9ef;">isPalindrome</span><span style="color:#f8f8f2;">(</span><span style="color:#66d9ef;">int</span> <span style="color:#f8f8f2;">no</span><span style="color:#f8f8f2;">,</span> <span style="color:#66d9ef;">int</span> <span style="color:#f8f8f2;">tempVar</span><span style="color:#f8f8f2;">,</span> <span style="color:#66d9ef;">int</span> <span style="color:#f8f8f2;">sum</span><span style="color:#f8f8f2;">)</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">{ </span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">if</span><span style="color:#f8f8f2;">(</span><span style="color:#f8f8f2;">no</span> <span style="color:#f92672;">&lt;</span> <span style="color:#e7a37a;">0</span><span style="color:#f8f8f2;">)</span> <span style="color:#f92672;">return</span> <span style="color:#66d9ef;">false</span><span style="color:#f8f8f2;">;</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">if</span><span style="color:#f8f8f2;">(</span><span style="color:#f8f8f2;">no</span> <span style="color:#f92672;">==</span> <span style="color:#e7a37a;">0</span><span style="color:#f8f8f2;">)</span> <span style="color:#f92672;">return</span> <span style="color:#f8f8f2;">sum</span> <span style="color:#f92672;">==</span> <span style="color:#f8f8f2;">tempVar</span><span style="color:#f8f8f2;">;</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">return</span> <span style="color:#66d9ef;">isPalindrome</span><span style="color:#f8f8f2;">(</span><span style="color:#f8f8f2;">no</span><span style="color:#f92672;">/</span><span style="color:#e7a37a;">10</span><span style="color:#f8f8f2;">,</span> <span style="color:#f8f8f2;">tempVar</span><span style="color:#f8f8f2;">,</span> <span style="color:#66d9ef;">sum *</span> <span style="color:#e7a37a;">10</span> <span style="color:#f92672;">+</span> <span style="color:#f8f8f2;">(</span><span style="color:#f8f8f2;">no</span><span style="color:#f92672;">%</span><span style="color:#e7a37a;">10</span><span style="color:#f8f8f2;">)</span><span style="color:#f8f8f2;">)</span><span style="color:#f8f8f2;">;</span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">}</span></span></span> 
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      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f92672;">public</span> <span style="color:#f92672;">static</span> <span style="color:#66d9ef;">void</span> <span style="color:#66d9ef;">main</span><span style="color:#f8f8f2;">(</span><span style="color:#66d9ef;">String</span><span style="color:#f8f8f2;">[</span><span style="color:#f8f8f2;">]</span> <span style="color:#f8f8f2;">args</span><span style="color:#f8f8f2;">)</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">{ </span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#66d9ef;">int</span> <span style="color:#f8f8f2;">a</span><span style="color:#f8f8f2;">[</span><span style="color:#f8f8f2;">]</span> <span style="color:#f92672;">=</span> <span style="color:#f8f8f2;">{ </span><span style="color:#e7a37a;">4</span><span style="color:#f8f8f2;">,</span> <span style="color:#e7a37a;">434</span><span style="color:#f8f8f2;">,</span> <span style="color:#e7a37a;">909</span><span style="color:#f8f8f2;">,</span> <span style="color:#e7a37a;">100</span><span style="color:#f8f8f2;">,</span> <span style="color:#f92672;">-</span><span style="color:#e7a37a;">66</span><span style="color:#f8f8f2;">,</span> <span style="color:#e7a37a;">123</span><span style="color:#f8f8f2;">,</span> <span style="color:#e7a37a;">797</span><span style="color:#f8f8f2;">}</span><span style="color:#f8f8f2;">;</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">for</span><span style="color:#f8f8f2;">(</span><span style="color:#66d9ef;">int</span> <span style="color:#f8f8f2;">i</span> <span style="color:#f92672;">=</span> <span style="color:#e7a37a;">0</span><span style="color:#f8f8f2;">;</span> <span style="color:#f8f8f2;">i</span> <span style="color:#f92672;">&lt;</span> <span style="color:#f8f8f2;">a</span><span style="color:#f8f8f2;">.</span><span style="color:#f8f8f2;">length</span><span style="color:#f8f8f2;">;</span> <span style="color:#f8f8f2;">i</span><span style="color:#f92672;">++</span><span style="color:#f8f8f2;">)</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">if</span><span style="color:#f8f8f2;">(</span><span style="color:#66d9ef;">isPalindrome</span><span style="color:#f8f8f2;">(</span><span style="color:#f8f8f2;">a</span><span style="color:#f8f8f2;">[</span><span style="color:#f8f8f2;">i</span><span style="color:#f8f8f2;">]</span><span style="color:#f8f8f2;">,</span> <span style="color:#f8f8f2;">a</span><span style="color:#f8f8f2;">[</span><span style="color:#f8f8f2;">i</span><span style="color:#f8f8f2;">]</span><span style="color:#f8f8f2;">,</span> <span style="color:#e7a37a;">0</span><span style="color:#f8f8f2;">)</span><span style="color:#f8f8f2;">)</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">System</span><span style="color:#f8f8f2;">.</span><span style="color:#f8f8f2;">out</span><span style="color:#f8f8f2;">.</span><span style="color:#66d9ef;">println</span><span style="color:#f8f8f2;">(</span><span style="color:#e6db74;">"The number "</span> <span style="color:#f92672;">+</span> <span style="color:#f8f8f2;">a</span><span style="color:#f8f8f2;">[</span><span style="color:#f8f8f2;">i</span><span style="color:#f8f8f2;">]</span> <span style="color:#f92672;">+</span><span style="color:#e6db74;">" is a palindrome number."</span><span style="color:#f8f8f2;">)</span><span style="color:#f8f8f2;">;</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f92672;">else</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span style="color:#f8f8f2;">System</span><span style="color:#f8f8f2;">.</span><span style="color:#f8f8f2;">out</span><span style="color:#f8f8f2;">.</span><span style="color:#66d9ef;">println</span><span style="color:#f8f8f2;">(</span><span style="color:#e6db74;">"The number "</span> <span style="color:#f92672;">+</span> <span style="color:#f8f8f2;">a</span><span style="color:#f8f8f2;">[</span><span style="color:#f8f8f2;">i</span><span style="color:#f8f8f2;">]</span> <span style="color:#f92672;">+</span><span style="color:#e6db74;">" is not a palindrome number."</span><span style="color:#f8f8f2;">)</span><span style="color:#f8f8f2;">;</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">}</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;"><span style="color:#f8f8f2;">}</span></span></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#666666;"><span style="color:#ffffff;">&nbsp;</span></span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

**输出：**

**说明：同样**在递归方法中，我们创建了该数字的副本，然后将其与我们反转的数字进行比较。注意，根据数学定义，**负数永远不能是回文数**。

import java.util.*;   
    class PalindromeExample2  
    {  
       public static void main(String args[])  
       {  
          String original, reverse = ""; // Objects of String class  
          Scanner in = new Scanner(System.in);   
          System.out.println("Enter a string/number to check if it is a palindrome");  
          original = in.nextLine();   
          int length = original.length();   
          for ( int i = length - 1; i >= 0; i-- )  
             reverse = reverse + original.charAt(i);  
          if (original.equals(reverse))  
             System.out.println("Entered string/number is a palindrome.");  
          else  
             System.out.println("Entered string/number isn't a palindrome.");   
       }  
    }