ソースコード 

VMRuntime vmRuntime = VMRuntime.getRuntime();
long externalBytesAllocated = vmRuntime.getExternalBytesAllocated();
long minimumHeapSize = vmRuntime.getMinimumHeapSize();
float heapUtilization = vmRuntime.getTargetHeapUtilization();
vmRuntime.setMinimumHeapSize(minimumHeapSize);
vmRuntime.setTargetHeapUtilization(heapUtilization);