java String Concatenation

The + operator joins two strings together. If either operand is String, the other is converted to String and concatenated with it. This is a common way to convert numbers to Strings.

If a non-String object is concatenated with a String, its toString() method is called. When you write a class that might have a sensible representation as a string, it's useful for debugging purposes to override Object's useless toString() method.

"abc" + "def"	"abcdef"
"abc" + 4	"abc4"
"1" + 2	"12"
"xyz" + (2+2 == 4)	"xyztrue"
1 + "2.5"	"12.5"