New to Java and having issues writing and example

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Regarding the “uninitialized variables”:
The simplest fix is to initialize the variables to some value of your choice, e.g.:

double price1 = 0.0;
double price2 = 0.0;

Though your code compiles just fine on my machine (java 1.8.0_91).

But be careful how the values are initialized/changed during program flow. E.g. and invalid input in one of the two switch-statements would cause your program to spit out an incorrect value.

Instead use an approach that removes redundant variables. E.g.: why use multiple variables for summing up the total price? Simply reuse a single variable for all additions:

double price = baseunit; //we know for sure the user selected the base-unit

...

switch(total1){
    case 1:
        price += screen1;
        break;
    ...
}

...

Don’t create variables for single-use values. Eliminate the usage of total1 and total2:

double baseunit = 375.99;
double screen1 = 75.99;
double screen2 = 99.99;
double dvd = 65.99;
double printer = 125.0;
double price1;
double price2;

...

switch(keyboard.nextInt()){
     ...
}

...

Simply continuing a program, after the user entered an invalid input won’t produce any useful/correct value. Notify him about the fact that the value he entered was useless and afterwards either terminate or ask again:

switch(keyboard.nextInt()){
     ...

     default:
         System.out.println("Invalid input");
         return;     //invalid input was entered, program is terminated
}

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