2.11. Mixed Up Code Practice

The coding problems below are mostly about Strings, but more problems on other topics in this unit will be added in the future.

Try to solve each of the following. Click the Check Me button to check each solution. You will be told if your solution is too short, has a block in the wrong order, or you are using the wrong block. Some of the problems have an extra block that isn’t needed in the correct solution.

The main method in the following class should print a random number from 1 to 50. But, the blocks have been mixed up and may include an extra block that isn’t needed in the solution. Drag the needed blocks from the left and put them in the correct order on the right. Click the Check Me button to check your solution.

        public class Test1
{
---
    public static void main(String[] args)
    {
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        int num = (int)(Math.random() * 50) + 1;
---
        System.out.println(num);
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    } // end main method

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} // end of class
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        int num = Math.random() * 50; #distractor
        

The main method in the following class should print the first 2 characters of the message followed by the last 2 characters of the message. But, the blocks have been mixed up and include an extra block that isn’t needed in the solution. Drag the needed blocks from the left and put them in the correct order on the right. Click the Check Me button to check your solution.

        public class Test1
{
---
    public static void main(String[] args)
    {
---
        String message = "I hope this works";
---
        String part1 = message.substring(0,2);
        String part2 = message.substring(message.length() - 2);
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        System.out.println(part1 + part2);
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    } // end main method
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} // end class
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        System.out.println(part1 * part2); #distractor
        

The main method in the following class should print the initials in lowercase letters. But, the blocks have been mixed up and include an extra block that isn’t needed in the solution. Drag the needed blocks from the left and put them in the correct order on the right. Click the Check Me button to check your solution.

        public class Test1
{
---
    public static void main(String[] args)
---
    {
---
        String first = "Gerald";
        String middle = "Foster";
        String last= "Jones";

---
        String initials = first.substring(0,1) +
                          middle.substring(0,1) +
                          last.substring(0,1);
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        String lowerInitials = initials.toLowerCase();
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        System.out.println(lowerInitials);
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    }
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}
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        System.out.println(initials); #distractor
        

The main method in the following class should print the message in all uppercase letters. But, the blocks have been mixed up and include an extra block that isn’t needed in the solution. Drag the needed blocks from the left and put them in the correct order on the right. Click the Check Me button to check your solution.

        public class Test1
{
---
    public static void main(String[] args)
---
    {
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        String message = "Don't Pokemon and drive!";
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        String upperMessage = message.toUpperCase();
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        System.out.println(upperMessage);
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    }
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}
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       System.print(upperMessage); #distractor
        

The main method in the following class should print the first 3 letters of message in uppercase letters. But, the blocks have been mixed up and include an extra block that isn’t needed in the solution. Drag the needed blocks from the left and put them in the correct order on the right. Click the Check Me button to check your solution.

        public class Test1
{
---
    public static void main(String[] args)
---
    {
---
        String message = "Have a nice day!";
---
        String part = message.substring(0,3);
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        String upper = part.toUpperCase();
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        System.out.println(upper);
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    }
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}
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        String part = message.substring(0,4); #distractor
        

The main method in the following class should print the part of the message starting with the word “nice”. But, the blocks have been mixed up and include an extra block that isn’t needed in the solution. Drag the needed blocks from the left and put them in the correct order on the right. Click the Check Me button to check your solution.

        public class Test1
{
---
    public static void main(String[] args)
---
    {
---
        String message = "Have a nice day!";
---
        int pos = message.indexOf("nice");
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        System.out.println(message.substring(pos));
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    }
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}
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        int pos = message.indexof("nice"); #distractor
        

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