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31 lines
1,014 B
Markdown
31 lines
1,014 B
Markdown
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# Lecture on October 4th
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## Pass by Copy vs Pass by Reference
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### Pass by Copy
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When you pass a primitive type into a method (int, char, double, float, etc), it makes a copy of the value of the variable and brings it into the method
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### Pass by Reference
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When you pass an array into a method (int[], char[], double[], etc[]), it passes in the reference of the variable into the method. In other words, you give the actual array into the method and allows the method to change it.
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### What's the Implication?
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If you change the primitive in a method, it doesn't actually change the value of the variable.
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If you pass in an array and change it in the method, it has been permanently changed outside the method as well.
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### How do I make it so I can't change my array by accident?
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Use the `final`keyword in the method header
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```java
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public static void printAll(final int[] array) {
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for (int i = 0; i < array.length; i++) {
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System.out.println("Number " + (i + 1) + " is " + array[i])
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}
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}
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```
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