String Concatenation (VB.Net and Java Cross Reference Guide)

To concatenate two strings, use either the + or & operators. The & operator implicitly converts numbers. If you use the + operator to concatenate a string and a number, you have to cast the number as a string with CStr.

Alternatively, you can use the System.Text.StringBuilder class which frequently but not always provides faster code.

Dim FullName

Dim Age

//You can use + for strings.

FullName = "Prestwood"
Console.WriteLine("Hello " + FullName)

//For implicit casting, use &

Age = 35

Console.WriteLine(FullName & " is " & Age & " years old.")

'Implicit casting of numbers.

'

'This works:
MessageBox.Show(3.3)

'This fails:

'MessageBox.Show("" + 3.3)

'This works:
MessageBox.Show("" + CStr(3.3))

'Implicit casting &. This also works:

MessageBox.Show("" & 3.3)

In Java, you use either the String concatenation + operator or StringBulder class methods such as append. Since Java compilers frequently create intermediate objects when the + operator is used and don't when StringBuilder.append is used, the append method is faster than the + operator.

In general, use the convenience of a + operator when speed is not an issue. For example, when concatenating a small number of items and when code isn't executed very frequently. A decent rule of thumb is to use the + operator for general purpose programming and then optimize the + operator with StringBuilder.append as needed.

System.out.println("Hello" + " " + "Mike.");

StringBuilder myMsg = new StringBuilder();
 

myMsg.append("Hello ");

myMsg.append("Mike.");

 
System.out.println(myMsg);