Java Program to add leading zeros to a number

To add leading zeros to a number, you need to format the output. Let’s say we need to add 4 leading zeros to the following number with 3 digits.

int val = 290;

For adding 4 leading zeros above, we will use %07d i.e. 4+3 = 7. Here, 3, as shown above, is the number with 3 digits.

String.format("%07d", val);

The following is the final example.

Example

<span class="kwd">import</span><span class="pln"> java</span><span class="pun">.</span><span class="pln">util</span><span class="pun">.</span><span class="typ">Formatter</span><span class="pun">;</span>
<span class="kwd">public</span><span class="pln"> </span><span class="kwd">class</span><span class="pln"> </span><span class="typ">Demo</span><span class="pln"> </span><span class="pun">{</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="pun">{</span>
<span class="kwd">       int</span><span class="pln"> val </span><span class="pun">=</span><span class="pln"> </span><span class="lit">290</span><span class="pun">;</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="str">"Integer: "</span><span class="pun">+</span><span class="pln">val</span><span class="pun">);</span>
<span class="typ">       String</span><span class="pln"> formattedStr </span><span class="pun">=</span><span class="pln"> </span><span class="typ">String</span><span class="pun">.</span><span class="pln">format</span><span class="pun">(</span><span class="str">"%07d"</span><span class="pun">,</span><span class="pln"> val</span><span class="pun">);</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="str">"With leading zeros = "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> formattedStr</span><span class="pun">);</span>
<span class="pun">    }</span>
<span class="pun">}</span>

Output

Integer: 290
With leading zeros = 0000290