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How many string objects will be created in constant pool

 2 years ago
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How many string objects will be created in constant pool

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Consider following statement and log level is set to ERROR. Logging API being used is log4j. How many strings will be created given above information?

if (logger.isDebugEnabled()) {
    logger.debug("Executing SQL query [" + sql + "]");
}

Other question is

if (logger.isDebugEnabled()) {
     StringBuilder sBuilder = new StringBuilder("Executing SQL query [");
     sBuilder.append(sql);
     sBuilder.append("]");
     logger.debug(sBuilder.toString());
}

How many string will be created in above case ?

My question is will compiler create strings even if logger is not enabled for debug ?

logger.debug("Executing SQL query [" + sql + "]");

Two strings

"Executing SQL query [" 

"]"

created at compile time.

And then, in Runtime,

"Executing SQL query [" + sql + "]"

(+) operator JVM returns new StringBuilder(string...).toString() which creates a new String instance in heap memory.

Append operation will happen with StringBuilder.toString ,If debug enable.


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