Test.java

import java.lang.reflect.*;
import java.util.Random;

class Test{
	static {
	    try {
	      Field field = Math.class.getDeclaredField("randomNumberGenerator");
	      field.setAccessible(true);
	      
	      field.set(null, new Random(){
	          @Override
	          public double nextDouble(){
	              return 1;
	          }
	      });
	    }
	    catch (Exception e) {
	      throw new RuntimeException(e);
	    }
	}

	public static void main(String[] args){
		System.out.println( java.lang.Math.random() );
	}
}