How to load game data from file?

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I have tried to save the game data into the file using Serializable and now I want to load the saved data from the file into a new JFrame. Actually what I'm trying to do is if the player clicks on continue button, the game will start from the state where it was left off and have been saved when we play it again. Hope you can help me resolve this problem. Thank you in advance.

This is the errors I got:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at java.awt.Container.updateGraphicsData(Container.java:1158)
        at java.awt.Container.updateGraphicsData(Container.java:1160)
        at java.awt.Container.updateGraphicsData(Container.java:1160)
        at java.awt.Container.updateGraphicsData(Container.java:1160)
        at java.awt.Container.updateGraphicsData(Container.java:1160)
        at java.awt.Component.setGraphicsConfiguration(Component.java:1153)
        at java.awt.Window.setGraphicsConfiguration(Window.java:3177)
        at java.awt.Window.initGC(Window.java:478)
        at java.awt.Window.initDeserializedWindow(Window.java:2987)
        at java.awt.Window.readObject(Window.java:3075)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1158)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2176)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2067)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1571)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:431)
        at javax.swing.event.EventListenerList.readObject(EventListenerList.java:274)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1158)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2176)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2067)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1571)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2285)
        at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:561)
        at javax.swing.JComponent.readObject(JComponent.java:5467)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1158)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2176)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2067)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1571)
        at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1973)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1565)
        at java.io.ObjectInputStream.access$800(ObjectInputStream.java:214)
        at java.io.ObjectInputStream$GetFieldImpl.readFields(ObjectInputStream.java:2450)
        at java.io.ObjectInputStream.readFields(ObjectInputStream.java:601)
        at java.awt.Container.readObject(Container.java:3720)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1158)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2176)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2067)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1571)
        at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1973)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1565)
        at java.io.ObjectInputStream.access$800(ObjectInputStream.java:214)
        at java.io.ObjectInputStream$GetFieldImpl.readFields(ObjectInputStream.java:2450)
        at java.io.ObjectInputStream.readFields(ObjectInputStream.java:601)
        at java.awt.Container.readObject(Container.java:3720)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1158)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2176)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2067)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1571)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:431)
        at GameLogic$Main.actionPerformed(GameLogic.java:278)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
        at java.awt.Component.processMouseEvent(Component.java:6533)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
        at java.awt.Component.processEvent(Component.java:6298)
        at java.awt.Container.processEvent(Container.java:2238)
        at java.awt.Component.dispatchEventImpl(Component.java:4889)
        at java.awt.Container.dispatchEventImpl(Container.java:2296)
        at java.awt.Component.dispatchEvent(Component.java:4711)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4897)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4534)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4475)
        at java.awt.Container.dispatchEventImpl(Container.java:2282)
        at java.awt.Window.dispatchEventImpl(Window.java:2746)
        at java.awt.Component.dispatchEvent(Component.java:4711)
        at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
        at java.awt.EventQueue.access$500(EventQueue.java:97)
        at java.awt.EventQueue$3.run(EventQueue.java:709)
        at java.awt.EventQueue$3.run(EventQueue.java:703)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
        at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
        at java.awt.EventQueue$4.run(EventQueue.java:733)
        at java.awt.EventQueue$4.run(EventQueue.java:731)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

What I have tried:

class GameLogic extends ... {
/*...
.
.
.*/

static Board board;
/*...
.
.
.*/

else if(btnTxt.equals("Save")) {
				
				try {
				FileOutputStream file = new FileOutputStream("chess.txt");
				ObjectOutputStream object = new ObjectOutputStream(file);
				object.writeObject(board);
				object.close();
			 // create a dialog Box 
			 JFrame f = new JFrame();
            JDialog d = new JDialog(f, "Chess Game"); 
  
            // create a label 
            JLabel l = new JLabel("Game is successfully saved!"); 
  
            d.add(l); 
  
            // setsize of dialog 
            d.setSize(200,100); 
			d.setLocationRelativeTo(null);
  
            // set visibility of dialog 
            d.setVisible(true); 

			}
			catch(Exception ex)
			{
				ex.printStackTrace();
			}


		} // close save
		else if(btnTxt.equals("Continue"))
		{
			JFrame fr1 = new JFrame();
			try {
		FileInputStream fileInputStream = new FileInputStream("chess.txt");
		BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream);
		ObjectInputStream objectInputStream = new ObjectInputStream(bufferedInputStream);
		Board object = (Board)objectInputStream.readObject();
		objectInputStream.close();
		} catch(IOException fe)
		{
			fe.printStackTrace();
		} catch(ClassNotFoundException ce)
		{
			ce.printStackTrace();
		}
		} // close continue

Posted 22-Sep-18 8:42am

Member 13620781

Updated 22-Sep-18 21:24pm

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Richard MacCutchan · Answer 1 · 2018-09-22T21:24:00

This is the same problem as your previous question on the subject. In your Continue section you do this:

Java

Board object = (Board)objectInputStream.readObject();

So as soon as you exit this routine that object goes out of scope and gets thrown away. Go to the Java reference and learn about scope and lifetime of objects.

Also, do not use reserved names such as object for your variables.