JVM Memory The following code shows how to access available, total and maximum memory of JVM using Runtime.
package com.bethecoder.tutorials.runtime; import java.text.DecimalFormat; import java.text.NumberFormat; public class RuntimeInfoTest { public static void main ( String [] args ) { System.out.println ( "Number of processors available to the JVM : " + Runtime.getRuntime () .availableProcessors ()) ; System.out.println ( "Free memory in the JVM : " + bytes2String ( Runtime.getRuntime () .freeMemory ())) ; System.out.println ( "Total memory in the JVM : " + bytes2String ( Runtime.getRuntime () .totalMemory ())) ; System.out.println ( "Maximum amount of memory that the JVM will attempt to use : " + bytes2String ( Runtime.getRuntime () .maxMemory ())) ; } public static final long SPACE_KB = 1024 ; public static final long SPACE_MB = 1024 * SPACE_KB; public static final long SPACE_GB = 1024 * SPACE_MB; public static String bytes2String ( double dataSize ) { NumberFormat nf = new DecimalFormat () ; nf.setMaximumFractionDigits ( 2 ) ; try { if ( dataSize < SPACE_KB ) { return nf.format ( dataSize ) + " Bytes" ; } else if ( dataSize < SPACE_MB ) { return nf.format ( dataSize/SPACE_KB ) + " KB" ; } else if ( dataSize < SPACE_GB ) { return nf.format ( dataSize/SPACE_MB ) + " MB" ; } else { return nf.format ( dataSize/SPACE_GB ) + " GB" ; } } catch ( Exception e ) { return dataSize + " Bytes" ; } } /* end of bytes2String method */ }
Number of processors available to the JVM : 1
Free memory in the JVM : 4.74 MB
Total memory in the JVM : 4.94 MB
Maximum amount of memory that the JVM will attempt to use : 63.56 MB
