Counting String objects created by Java code

Question

How many String objects are created by the following code?

String x = new String(\"xyz\");
String y = \"abc\";
x = x + y;

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Answer 1

I would say 4 because:

• x + y will be replaced by the compiler with a StringBuilder implementation. +1
• new always creates a new object. +1
• Different constants are different objects. +2

Here's how:

String x = new String("xyz"); // 2 objects created: the variable and the constant
String y = "abc"; // 1 object created: the variable
x = x + y; // 1 object created: the one by the StringBuilder class