e following has the correct code to ‘swap’ the values in x and y (so that x ends up with y’s initial value and y ends up with x’s initial value), but the code is mixed up and contains one extra block which is not needed in a correct solution. Drag the needed blocks from the left into the correct order on the right. Check your solution by clicking on the Check button. You will be told if any of the blocks are in the wrong order or if you need to remove one or more blocks. After three incorrect attempts you will be able to use the Help Me button to make the problem easier.

Pass by value¶ Java uses pass by Value when it passes arguments into a method. This means that a copy of the actual parameter value is stored in the formal parameter variable. The original value outside the method is not changed if a new value is assigned to the formal parameter within the method body. It is generally not a good idea to change the value of a formal parameter inside a method, however it is possible as the example below shows.

5-2-9: Which method has a scope error (i.e. uses a variable that is not visible in that method)?

You may recall from the constructor lesson that this is called “overloading”.

To draw something on the screen you would first set the pen color: StdDraw.setPenColor(Color.GREEN); //or use a custom color here! You can then use one of the API methods to draw something on the canvas: StdDraw.filledSquare(0.5, 0.5, 0.2);

One powerful feature in the array data abstraction is that we can use variables for the index! As long as the variable holds an integer, we can use it as an index.

4-4-2: What does the following code print?

Watch the following video for a tracing demo. When you are tracing through code, pretend to be the computer running the code line by line, repeating the code in the loop, and keeping track of the variable values and output.

Storing User Input in Variables

String is an object type and is the name of a class in Java. A string object has a sequence of characters enclosed in a pair of double quotes - like “Hello”.

5: Fill in the blank with code to access the cars array.

4-5-2

What are the values of var1 and var2 when the code finishes executing?

4-4-2: What does the following code print?

4-2-3

4-1-3

1-11-3: What does the following code print?

!= Does not equal

1-6-3: Which of the following returns the correct average for a total that is the sum of 3 int values?

✔️ Java throws away any values after the decimal point if you do integer division. It does not round up automatically.

Code Tracing Challenge and Operators Maze¶

y /= 2;