To find the second largest number in an array in Java, you can follow these steps:

1. Initialize two variables, largest and secondLargest, to hold the largest and second largest numbers, respectively. Set both variables to a very small value, such as Integer.MIN_VALUE.
2. Iterate through the array, comparing each element with the largest and secondLargest variables.
3. If the current element is greater than the largest value, update both largest and secondLargest. Set the current largest value to secondLargest, and the current element as the new largest value.
4. If the current element is smaller than the largest value but greater than the secondLargest value, update only the secondLargest value to the current element.
5. After iterating through the entire array, the secondLargest variable will hold the second largest number.

Here’s the Java code implementation:

<span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> <span class="hljs-title class_">SecondLargestNumber</span> {
<span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title function_">main</span><span class="hljs-params">(String[] args)</span> {
<span class="hljs-type">int</span>[] numbers = {<span class="hljs-number">5</span>, <span class="hljs-number">2</span>, <span class="hljs-number">10</span>, <span class="hljs-number">8</span>, <span class="hljs-number">1</span>, <span class="hljs-number">9</span>};

System.out.println(<span class="hljs-string">"The second largest number is: "</span> + secondLargest);
}
}


In this example, the array numbers contains six elements. The code iterates through each element and updates the largest and secondLargest variables accordingly. Finally, it prints the second largest number, which is 9 in this case.