JAVA EE: Java Tutorial : Java String vs StringBuffer vs StringBuilder(Performance)

Wednesday 11 May 2016

Java Tutorial : Java String vs StringBuffer vs StringBuilder(Performance)

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PerformanceTest.java

public class PerformanceTest
{

    /*
     * String is slow and consumes more memory when you
     * concat too many strings because every time it creates
     * new instance.
     */
    public static String concatenatingWithString()
    {
        String str = "Welcome";
        for (int i = 0; i < 70000; i++)
        {
            str = str + "Peter";
        }
        return str;
    }

    /*
     * StringBuffer is fast and consumes less memory when
     * you cancat strings.
     * 
     * StringBuffer is faster than String.
     */
    public static String concatenatingWithStringBuffer()
    {
        StringBuffer sb = new StringBuffer("Welcome");
        for (int i = 0; i < 70000; i++)
        {
            sb.append("Peter");
        }
        return sb.toString();
    }

    /*
     * StringBuilder is fast and consumes less memory when
     * you cancat strings.
     * 
     * StringBuilder is faster than StringBuffer.
     */
    public static String concatenatingWithStringBuilder()
    {
        StringBuilder sb = new StringBuilder("Welcome");
        for (int i = 0; i < 70000; i++)
        {
            sb.append("Peter");
        }
        return sb.toString();
    }

    public static void main(String[] args)
    {
        long startTime = System.currentTimeMillis();

        concatenatingWithString();

        System.out
                .println("Time taken by Concatenating with String       : "
                        + (System.currentTimeMillis() - startTime)
                        + "ms");

        startTime = System.currentTimeMillis();

        concatenatingWithStringBuffer();

        System.out
                .println("Time taken by Concatenating with StringBuffer :  "
                        + (System.currentTimeMillis() - startTime)
                        + "ms");

        startTime = System.currentTimeMillis();

        concatenatingWithStringBuilder();

        System.out
                .println("Time taken by Concatenating with StringBuilder: "
                        + (System.currentTimeMillis() - startTime)
                        + "ms");
    }
}

Output

Time taken by Concatenating with String       : 17394ms
Time taken by Concatenating with StringBuffer :  20ms
Time taken by Concatenating with StringBuilder: 10ms