How to program the Boolean statement, getting error

Now as far as code goes: line 21 has an error in that you are trying to set the value to true, but the double equal sign (==) is a comparison operator and not an assignment operator. On line 23 you can just write the variable if(triangle) instead of if(triangle == true). This is because if() is checking for boolean values true or false. You declare the variable triangle to be a boolean of (disregarding the error) true. if-else statements only need code blocks if they are to execute more than 1 statement. If you have 1 and only 1 statement, then the block is unnecessary. Now it is not against any rule to add blocks if you don't need them, but keeping your code small (within reason) is desirable. It really would be your preference, but you can write your code like this:

if(/*boolean check*/)
      System.out.println("Some text");
else
      System.out.println("some other text");