What is the Data Type of 'a' 'b' in Java?

The Data Type of 'a' 'b' in Java

When performing character addition ('a' 'b'), Java automatically promotes the operands to integers, resulting in an integer output. This promotion is due to binary numeric promotion rules.

Binary Numeric Promotion in Java

According to the Java Language Specification, the following rules govern binary numeric promo
tion:

• If either operand is double, both are converted to double.
• If either operand is float, both are converted to float.
• If either operand is long, both are converted to long.
• Otherwise, both operands are converted to int.

Therefore, since 'a' and 'b' are char types, they will both be promoted to int during the addition operation, resulting in an int output.

Note on Compound Assignment Operators

However, when using compound assignment operators like =, these rules may not apply. In such cases, the result is converted to the type of the left-hand variable, potentially leading to data truncation or loss of precision.

Identifying the Output Data Type

To determine the output data type, you can cast the result to an Object and check its class:

System.out.println(((Object)('a' + 'b')).getClass());
// Output: class java.lang.Integer

Options for String Concatenation

If you wish to concatenate characters as a String rather than performing numeric addition, you can use the following options:

• Add an empty string to the expression: 'a' "" 'b'
• Use the StringBuilder class: new StringBuilder().append('a').append('b').toString()
• Use the String.format() method: String.format("%c%c", 'a', 'b')

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