Java: enough free heap to create an object?

try {
    // try to perform an operation using a huge in-memory array
    byte[] massiveArray = new byte[BIG_NUMBER];
}
catch (OutOfMemoryError oome) {
    // perform the operation in some slower but less
    // memory intensive way...
}

if (Runtime.getRuntime().freeMemory() > SOME_MEMORY) {
    // quick memory-intensive approach
}
else {
    // slower, less demanding approach
}

-Xmx

java -Xmx8g some.name.YourMemConsumingApp

if( isEnoughMemory( SOME_MEMORY ) ){
    strategy = new InMemoryStrategy();
 }else{
    strategy = new DiskStrategy();
}

 strategy.performTheAction();

...
strategy = new ImaginaryCloudComputingStrategy();
...

while( !isDone() ) {
      if( isMemoryLow() ){ //Runtime.getRuntime().freeMemory() < SOME_MEMORY + some other validations
           swapToDisk(); // and make sure resources are GC'able
       }
       byte [] array new byte[PREDEFINED_BUFFER_SIZE];
       process( array );

       process( array );
 }
 cleanUp();