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content/ta/spring2018/cpsc220/mar22.md

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+# Lecture on March 22nd
+
+## Method Documentation
+
+Java has a special way that you can document your methods such that it will create documentation for you if you follow the convention.
+
+The Java API actually uses this technique to produce its own documentation.
+
+To create this, indicate a method with special comments that begin with `/**` and ends with `*/`
+
+It contains *block tags* that describe input and output parameters
+
+`@param` and `@return`
+
+### Example
+
+```java
+/**
+ * @param y an integer to sum
+ * @param x an integer to sum
+ * @return the sum of x and y
+ */
+public int multiply(int x, int y) {
+    return x + y;
+}
+```
+
+## Passing a Scanner
+
+We only want to create one **user input scanner** per program, we also only want one **file input scanner** per program.
+
+If a method needs a scanner, you can pass the one you already created in as an input parameter.
+
+## Array as Input Parameter
+
+Primitive types (`int`, `char`, `double`, etc.) are passed by value. Modifications made inside a method cannot be seen outside the method.
+
+Arrays on the other hand, is pass by reference. Changes made to an array inside the method can be seen outside the method.
+
+```java
+public static void main(String[] args) {
+    int[] nums = {1, 3, 5, 7, 9};
+    
+    timesTwo(nums);
+}
+public static void timesTwo(int[] arr) {
+    for (int i = 0; i < arr.length; i++) {
+        arr[i] *= 2;
+    }
+}
+```
+
+At the end of the `timesTwo` method call, the variable `nums` would have `{2, 6, 10, 14, 18}`
+
+## Sizes of Arrays
+
+### Perfect Size Arrays
+
+When we declare an array, Java automatically fills every slot of the array with the type in memory. So if you know that you need exactly 8 slots, then you only ask for 8.
+
+### Oversize Arrays
+
+This is when we don't know how many slots we need. Therefore, we ask for more than we think we'll need. That way we don't go out of bounds.
+
+If we do this, then we don't know how many elements we have already inserted into the array. Since the length is the number of slots.
+
+So we can create another variable, which will keep track of the index in where we can add the next element.
+
+We use oversized arrays when the size of the array is unknown or may change.
+
+
+