What's the best way to build a string of delimited items in Java?

Question

While working in a Java app, I recently needed to assemble a comma-delimited list of values to pass to another web service without knowing how many elements there would be i

Answer 1

If you're using Eclipse Collections, you can use makeString() or appendString().

makeString() returns a String representation, similar to toString().

It has three forms

• makeString(start, separator, end)
• makeString(separator) defaults start and end to empty strings
• makeString() defaults the separator to ", " (comma and space)

Code example:

MutableList list = FastList.newListWith(1, 2, 3);
assertEquals("[1/2/3]", list.makeString("[", "/", "]"));
assertEquals("1/2/3", list.makeString("/"));
assertEquals("1, 2, 3", list.makeString());
assertEquals(list.toString(), list.makeString("[", ", ", "]"));

appendString() is similar to makeString(), but it appends to an Appendable (like StringBuilder) and is void. It has the same three forms, with an additional first argument, the Appendable.

MutableList list = FastList.newListWith(1, 2, 3);
Appendable appendable = new StringBuilder();
list.appendString(appendable, "[", "/", "]");
assertEquals("[1/2/3]", appendable.toString());

If you can't convert your collection to an Eclipse Collections type, just adapt it with the relevant adapter.

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