StringConcatBench.java

import java.util.Formatter;

public class Bench {
    private String fileName = "foo.java";
    private String className = "class.dayo";
    private String methodName = "methodDayo";
    private int lineNumber = 42;

    public void benchStringBuilder() {
        for (int i=0; i<1_000_000; ++i) {
            new StringBuilder()
                .append("File Name: ")
                .append(fileName)
                .append(", Class Name: ")
                .append(className)
                .append(", Method Name: ")
                .append(methodName)
                .append(", Line Number: ")
                .append(lineNumber)
                .toString();
        }
    }

    public void benchStringFormat() {
        for (int i=0; i<1_000_000; ++i) {
            String.format("File name: %s, Class Name: %s, Method Name: %s, Line Number: %d", fileName, className, methodName, lineNumber);
        }
    }

    public void benchFormatterFormat() {
        for (int i=0; i<1_000_000; ++i) {
            StringBuilder sb = new StringBuilder();
            Formatter formatter = new Formatter(sb);
            formatter.format("File name: %s, Class Name: %s, Method Name: %s, Line Number: %d", fileName, className, methodName, lineNumber);
        }
    }
}

/*
Score:

benchStringBuilder:  1 wallclock secs ( 0.99 usr +  0.05 sys =  1.03 CPU) @ 16.45/s (n=17)
benchStringFormat:  1 wallclock secs ( 1.89 usr +  0.00 sys =  1.90 CPU) @  0.53/s (n=1)
benchFormatterFormat:  1 wallclock secs ( 1.83 usr +  0.00 sys =  1.84 CPU) @  0.55/s (n=1)

Comparison chart:

                           Rate  benchStringBuilder  benchStringFormat  benchFormatterFormat
    benchStringBuilder   16.4/s                  --              3009%                 2916%
     benchStringFormat  0.529/s                -97%                 --                   -3%
  benchFormatterFormat  0.545/s                -97%                 3%                    --
*/