How does Java concatenate 2 strings?

Question

Why does the following print 197, but not 'bc'?

System.out.println('b' + 'c');

Can someone explain how to do proper concatenation on Java?

PS I learnt some Python, and now transforming to learn Java.

Answer 1

'b' and 'c' are not String s, they are char s. You should use double quotes "..." instead:

System.out.println("b" + "c");

You are getting an int because you are adding the unicode values of those characters:

System.out.println((int) 'b'); // 98
System.out.println((int) 'c'); // 99
System.out.println('b' + 'c'); // 98 + 99 = 197

Answer 2

'b' is not a String in Java it is char . Then 'b'+'c' prints 197 .

But if you use "b"+"c" this will prints bc since "" used to represent String .

System.out.println("b" + "c"); // prints bc

Answer 3

Concatenating chars using + will change the value of the char into ascii and hence giving a numerical output. If you want bc as output, you need to have b and c as String. Currently, your b and c are char in Java.

In Java, String literals should be surrounded by "" and Character are surrounded by ''

Answer 4

Yes single quotation is Char while double quote represent string so:

System.out.println("b" + "c");

Some alternatives can be:

"" + char1 + char2 + char3;

or:

new StringBuilder().append('b').append('c').toString();

Answer 5

In Java, Strings literals are represented with double quotes - ""

What you have done is added two char values together. What you want is:

System.out.println("b" + "c"); // bc

What happened with your code is that it added the ASCII values of the chars to come up with 197 .

The ASCII value of 'b' is 98 and the ASCII value of 'c' is 99 .

So it went like this:

System.out.println('b' + 'c'); // 98 + 99 = 197

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As a note with my reference to the ASCII value of the chars :

The char data type is a single 16-bit Unicode character.

From the Docs . However, for one byte (0-255), as far as I'm aware, chars can also be represented by their ASCII value because the ASCII values directly correspond to the Unicode code point values - see here .

The reason I referenced ASCII values in my answer above is because the 256 ASCII values cover all letter (uppercase and lowercase) and punctuation - so it covers all of the main stuff.

Technically what I said is correct - it did add the ASCII values (because they are the same as the Unicode values). However, technically it adds the Unicode codepoint decimal values.

Answer 6

'b' and 'c' are not Strings they are characters. 197 is sum of unicode values of b and c

For Concatinating String you can use following 2 ways:

• System.out.println("b"+"c");
• System.out.println("b".concat("c"));