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Java: Concatenation

We already know about the mathematical operation of addition. Such a program:

System.out.print(5 + 3);

will display 8 - the result of the binary operator + with the operands 5 and 3.

Above the strings defined their operations. You can "fold" two lines. Such a program:

System.out.print("Dragon" + "stone");

will display Dragonstone - the result of the binary operator + with the 'Dragon' and 'stone' operands.

This operation is called concatenation. Roughly speaking, this is the "gluing" of the lines. Gluing always happens in the same order in which the operands are written, in other words, the left operand becomes the left part of the string, and the right operand becomes the left.

Here are some more examples:

System.out.print("Kings" + "wood");     // => Kingswood

System.out.print("Kings" + "road");     // => Kingsroad

System.out.print("King's" + "Landing"); // => King'sLanding

In the last example, the name of the city turned out to be with an error: King's Landing must be written with a space! But there were no spaces in our initial lines, and the spaces in the code to the left and right of the + character do not matter, because they are not part of the lines.

Let's try to solve this problem in different ways:

System.out.print("King's " + "Landing");      //  => King's Landing

System.out.print("King's" + " Landing");      //  => King's Landing

System.out.print("King's" + " " + "Landing"); //  => King's Landing

A space is the same character as the others, therefore, how many spaces to put in a line will be as much:

System.out.print("King's " + " Landing");   // => King's  Landing

System.out.print("King's  " + "  Landing"); // => King's    Landing



Winter came for the House of Frey.

using concatenation of words. Each word must be represented in a separate line. Do not forget about the spaces.

The exercise doesn't pass checking. What to do? 😶

If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:

  • Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨

Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.

My code is different from the teacher's one 🤔

It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.

In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.

I've read the lessons but nothing is clear 🙄

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