How Many Objects Does Java Create for Different String Initializations?

We analyze how many objects are created for String s = "long", new String("long"), and String s = "lo" + "ng" using diagrams.

1. Objects created by String s = new String("long")

String s = new String("long")

creates a String object and the variable s on the stack points to this instance, as shown:

The literal "long" is a string; the JVM first checks the string constant pool for this literal. If it does not exist, a constant object is created, as illustrated:

Finally, the string object references the "long" in the constant pool:

Therefore, if "long" is not already in the constant pool, String s = new String("long") creates two objects; otherwise, it creates only one.

2. Objects created by String s = "long"

The JVM checks the constant pool for the literal "long". If absent, it creates a constant object; if present, it reuses the existing one. Hence, String s = "long" may create an object or may not.

3. Objects created by String s = "lo" + "ng"

The compiler optimizes this concatenation, storing the resulting literal "long" in the constant pool. Consequently, String s = "lo" + "ng" behaves the same as String s = "long" regarding object creation.