Check if a string contains a number using Java.

To find whether a given string contains a number, convert it to a character array and find whether each character in the array is a digit using the isDigit() method of the Character class.

Example

<span class="kwd">public</span><span class="pln"> </span><span class="kwd">class</span><span class="pln"> </span><span class="typ">ContainsExample</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
   </span><span class="kwd">public</span><span class="pln"> </span><span class="kwd">static</span><span class="pln"> </span><span class="kwd">void</span><span class="pln"> main</span><span class="pun">(</span><span class="typ">String</span><span class="pln"> args</span><span class="pun">[]){</span><span class="pln">
      </span><span class="typ">String</span><span class="pln"> sample </span><span class="pun">=</span><span class="pln"> </span><span class="str">"krishna64"</span><span class="pun">;</span><span class="pln">
      </span><span class="kwd">char</span><span class="pun">[]</span><span class="pln"> chars </span><span class="pun">=</span><span class="pln"> sample</span><span class="pun">.</span><span class="pln">toCharArray</span><span class="pun">();</span><span class="pln">
      </span><span class="typ">StringBuilder</span><span class="pln"> sb </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">StringBuilder</span><span class="pun">();</span><span class="pln">
      </span><span class="kwd">for</span><span class="pun">(</span><span class="kwd">char</span><span class="pln"> c </span><span class="pun">:</span><span class="pln"> chars</span><span class="pun">){</span><span class="pln">
         </span><span class="kwd">if</span><span class="pun">(</span><span class="typ">Character</span><span class="pun">.</span><span class="pln">isDigit</span><span class="pun">(</span><span class="pln">c</span><span class="pun">)){</span><span class="pln">
            sb</span><span class="pun">.</span><span class="pln">append</span><span class="pun">(</span><span class="pln">c</span><span class="pun">);</span><span class="pln">
         </span><span class="pun">}</span><span class="pln">
      </span><span class="pun">}</span><span class="pln">
      </span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="pln">sb</span><span class="pun">);</span><span class="pln">
   </span><span class="pun">}</span><span class="pln">
</span><span class="pun">}</span>

Output

64