this is my code.... when I try to run it... the error message
plz help me fix the problem...
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java.io.InvalidClassException: Sphere; local class incompatible: stream classdesc serialVersionUID = 1, local class serialVersionUID = 7497003029646850194 at java.io.ObjectStreamClass.initNonProxy(Unknown Source) at java.io.ObjectInputStream.readNonProxyDesc(Unknown Source) at java.io.ObjectInputStream.readClassDesc(Unknown Source) at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) at java.io.ObjectInputStream.readObject0(Unknown Source) at java.io.ObjectInputStream.readObject(Unknown Source) at ObjectSaver.readAllObjects(ObjectSaver.java:46) at Main.main(Main.java:77) Exception in thread "main" java.lang.NullPointerException at Main.main(Main.java:78)
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Main.java
public class Main {
public static void main(String arg[]){ Shape cone = new Cone(20,10); Shape ellipsoid = new Ellipsoid(5,10,15); Shape sphere = new Sphere(30); ObjectSaver coneFile = new ObjectSaver<>( new File("cones.dat")); // should accpet any data file? .txt ObjectSaver ellipsoidFile = new ObjectSaver<>( new File("ellipsoids.dat")); ObjectSaver sphereFile = new ObjectSaver<>( new File("spheres.dat")); System.out.println( " write file test.............. "); try{ // cone System.out.println("Cone ->" + cone); if(coneFile.writeOneObject(cone, false)) { System.out.println("written to file."); } // ellipsoid System.out.println("Ellipsoid ->" + ellipsoid); if(ellipsoidFile.writeOneObject(ellipsoid, false)){ System.out.println("written to file."); } // sphere System.out.println("Sphere ->" + sphere); if(ellipsoidFile.writeOneObject(sphere, false)){ System.out.println("written to file."); } }catch(NotSerializableException e){ e.printStackTrace(); } // some bug... not solved yet System.out.println( " read file test.............. "); //cone ArrayList listFromFile = coneFile.readAllObjects(); Iterator iterator = listFromFile.iterator(); System.out.println(" cone file: "); while (iterator.hasNext()){ System.out.println(iterator.next()); } //ellipsoid // problem listFromFile = ellipsoidFile.readAllObjects(); iterator = listFromFile.iterator(); System.out.println(" elliposid file: "); while (iterator.hasNext()){ System.out.println(iterator.next()); } //sphere // problem listFromFile = sphereFile.readAllObjects(); iterator = listFromFile.iterator(); System.out.println(" sphere file: "); while (iterator.hasNext()){ System.out.println(iterator.next()); } ArrayList listOfShapes = new ArrayList<>(); // add listOfShapes.add(cone); listOfShapes.add(ellipsoid); listOfShapes.add(sphere); System.out.println(" Min V is: " + ShapeUtilities.min(listOfShapes)); System.out.println(" Max V is: " + ShapeUtilities.max(listOfShapes)); iterator = listOfShapes.iterator(); System.out.println("Sorted list is: "); while(iterator.hasNext()){ System.out.println(iterator.next()); } } }
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ObjectSaver.java
public class ObjectSaver {
private File file; public ObjectSaver(File file){ this.file = file; } // readOneObject // this method should also throw an IOException if the parameter is outside the range of possible object positions in the file. public T readOneObject(int index) throws IOException{ ArrayList result = readAllObjects(); // find object index and return back to function if((result == null) || (result.size() >= index)){ // if cannot read one, then return outside range throw new IOException("parameter is outside the range"); } else return result.get(index); } // readAllObjects // returns an ArrayList of Generic Type which holds all the objects read from the file. @SuppressWarnings("unchecked") public ArrayList readAllObjects(){ ArrayList result; FileInputStream fileInputStream = null; // declare to null ObjectInputStream objectInputStream = null; try{ fileInputStream = new FileInputStream(file); objectInputStream = new ObjectInputStream(fileInputStream); result = (ArrayList) objectInputStream.readObject(); return result; // // catch (FileNotFoundException e){e.printStackTrace();} // catch (IOException e){} // catch (Exception e){} }catch(FileNotFoundException e){ e.printStackTrace(); }catch(IOException e){ e.printStackTrace(); }catch(ClassNotFoundException e){ e.printStackTrace(); }finally{ // finally block use to exit try block
if(fileInputStream != null){ // inputsteam -> close try{ fileInputStream.close(); }catch(IOException e){ e.printStackTrace(); } } else if(objectInputStream != null){ try{ objectInputStream.close(); }catch(IOException e){ e.printStackTrace(); } } } return null; } // writeOneObject // takes a generic class type as a parameter. // takes a boolean value as a parameter. // if the value is true append to the end of the file, if false, overwrite the old contents of the file. // writes the object to the File. // this method should also throw a NotSerializableException. public boolean writeOneObject(T object, boolean append) throws NotSerializableException{ ArrayList fileContentWritten; if(append){ fileContentWritten = readAllObjects(); } else{ fileContentWritten = new ArrayList(); } fileContentWritten.add(object); writeAllObjects(fileContentWritten, append); return true; } // writeAllObjects // takes an ArrayList of any type as a parameter. // takes a boolean value as a parameter. // if the value is true append to the end of the file, if false, overwrite the old contents of the file. // writes all the objects in the ArrayList to the File specified in the constructor. // this method should also throw a NotSerializableException. public boolean writeAllObjects(ArrayList objectWritten, boolean append) throws NotSerializableException{ FileOutputStream fileOutputStream = null; //// declare to null ObjectOutputStream objectOutputStream = null; try{ fileOutputStream = new FileOutputStream(file); objectOutputStream = new ObjectOutputStream(fileOutputStream); objectOutputStream.writeObject(objectWritten); }catch (FileNotFoundException e){ e.printStackTrace(); }catch (IOException e){ e.printStackTrace(); }finally{ // finally block use to exit try block // https://docs.oracle.com/javase/ial/essential/exceptions/finally.html if(fileOutputStream != null){ // inputsteam -> close try{ fileOutputStream.close(); }catch(IOException e){ e.printStackTrace(); } } else if(objectOutputStream != null){ try{ objectOutputStream.close(); }catch(IOException e){ e.printStackTrace(); } } } // readallObjects & writeAllObjects // input & output return true; } }
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ShapeUtilities.java
public class ShapeUtilities { // recursiveSort() // This method takes an ArrayList of Bounded Generic type and // sorts it based on the volumes of the objects using the following algorithm. // The bound should only allow any Shape object and subclasses. public static ArrayList recursiveSort(ArrayList list){ if(list != null && list.size() <= 1){ return list; // if the list size <= 1 //return list } else{ // else select a middle element from the list and remove it int mid = list.size()/2; double midVolume = list.get(mid).getVolume(); // creat 2 lists leftlist and rightlist ArrayList leftList = new ArrayList<>(); ArrayList rightList = new ArrayList<>(); Iterator iterator = list.iterator(); int i = 0; // if element is less than the middle element then add element to the right // else add to left while(iterator.hasNext()){ // object next() return next element T current = iterator.next(); if (i != mid) { if (current.getVolume() < midVolume){ rightList.add(current); } else{ leftList.add(current); } } i++; // till string end; } leftList = recursiveSort(leftList); rightList = recursiveSort(rightList); ArrayList result = new ArrayList<>(); result.add(list.get(mid)); if(leftList.size()>0){ // add result to leftlist leftList.addAll(result); result = leftList; } else if(rightList.size()>0){ // else do add on rightlist result.addAll(rightList); } return result; // return the combination of recursiveSort } } // min(); // This method takes an ArrayList of Bounded Generic Type which only allows Shape objects and its subclasses. // The method should return the object with the maximum volume from the list of objects. public static T min(ArrayList list){ if(list != null && list.size() != 0){ Iterator iterator = list.iterator(); T minVolumeShape = list.get(0); while(iterator.hasNext()){ T currentShape = iterator.next(); if(currentShape.getVolume() < minVolumeShape.getVolume()){ minVolumeShape = currentShape; } } // return the minimum volume from the list of obj return minVolumeShape; } else return null; }// // max(); // This method takes an ArrayList of Bounded Generic Type which only allows Shape objects and its subclasses. // The method should return the object with the minimum volume from the list of objects. public static T max(ArrayList list){ if (list != null && list.size() != 0) { Iterator iterator = list.iterator(); T maxVolumeShape = list.get(0); while (iterator.hasNext()) { T currentShape = iterator.next(); if (currentShape.getVolume() > maxVolumeShape.getVolume()) { maxVolumeShape = currentShape; } } // return the maximum volume from the list of obj return maxVolumeShape; } else return null; }// same as min }
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Shape.java
public interface Shape {
public double getVolume(); }
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Sphere.java
public class Sphere implements Shape, Serializable{ private double radius; public Sphere(double radius){ this.radius =radius; } @Override //getVolume public double getVolume(){ return 3.14 * radius * radius * radius * 4 / 3 ; } public String toString(){ return "Type of shape: Sphere, Radius is: " + radius + ", Volume is: " + getVolume(); } // returns a string which includes the type of shape, the radius, and the volume.
}
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Ellipsoid.java
public class Ellipsoid implements Shape, Serializable{ private double radius1; private double radius2; private double radius3; public Ellipsoid(double radius1, double radius2, double radius3){ this.radius1 = radius1; this.radius2 = radius2; this.radius3 = radius3; }
@Override //getVolume public double getVolume(){ return 3.14 * radius1 * radius2 * radius3 * 4 / 3; } public String toString(){ return "Type of shape: Ellipsoid, Radius 1 is: " + radius1 + " Radius 2 is: " + radius2 + " Radius 3 is: " + radius3 + ", Volume is: " + getVolume(); } // returns a string which includes the type of shape, the radius, and the volume. }
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Cone.java
public class Cone implements Shape, Serializable{ private double height; private double radius; public Cone(double height, double radius){ this.height = height; this.radius = radius; } @Override //getVolume public double getVolume(){ return 3.14 * radius * radius * height / 3 ; // this one works // 1/3 * 3.14 * r * r *h doesnt work ??? } public String toString(){ return "Type of shape: Cone, Radius is: " + radius + ", Volume is: " + getVolume(); } // returns a string which includes the type of shape, the radius, and the volume.
}
