Problema di compilazione (Java)

[mariade]

Ciao ragazzi, volevo un vostro aiuto a capire dov'e' l'errore. Qui c'e' il codice, quando do' il comando javac da dos mi appare questo errore:
"C:\java>javac ShapeDrawJPanel.java
ShapeDrawJPanel.java:56: cannot find symbol
symbol : method getContentPane()
location: class ShapeDrawJPanel
getContentPane().setBackground(new Color(255,255,255));
^"

Volevo capire appunto cosa e' che sbaglio. Grazie mille!

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ShapeDrawJPanel extends JPanel {

private final int SHAPETYPES=3;
private int shapeType=0;
private String shapeTypes[]= {"Line","Oval", "Rectangle"};
private int numShapes=0; private int XYValues[] = new int[4];
private Shape[] shapes = new Shape[100];
private JLabel label;
private JComboBox shapesComboBox;
private JCheckBox filled;
private Container container;
private JPanel lowerRow;

public ShapeDrawJPanel() {


addMouseListener( new MouseClickHandler());


lowerRow = new JPanel();
label = new JLabel("You have to select the type of shape to draw");
lowerRow.add(label);

shapesComboBox = new JComboBox(shapeTypes);
shapesComboBox.setSelectedIndex(0);
lowerRow.add(shapesComboBox);
container.add(lowerRow, BorderLayout.SOUTH); setSize(600,600); setVisible( true );
}

public void paint( Graphics g) {
super.paint(g);
for (int sp=0;sp< shapes.length ; sp++) {
if(shapes[sp]!=null) {
shapes[sp].draw(g);
}}}

public void createShape(int index) {

numShapes++;
switch (index) {
case 0: shapes[numShapes] = new Line(XYValues); break;
case 1: shapes[numShapes] = new Oval(XYValues); break;
case 2: shapes[numShapes] = new Rectangle(XYValues); break;
}}

private class MouseClickHandler extends MouseAdapter {
public void mousePressed (MouseEvent event) {
XYValues[0] = event.getX();
XYValues[1] = event.getY(); }
}
public void mouseReleased (MouseEvent event) {
getContentPane().setBackground(new Color(255,255,255));
XYValues[2] = event.getX();
XYValues[3] = event.getY();
createShape(shapesComboBox.getSelectedIndex());
repaint();
}}

[spv42]

Mi sembra che getContentPane() non sia un metodo visibile da JPanel!!!

Ecco perchè ti dà errore.

[mariade]

Originariamente inviato da spv42

Mi sembra che getContentPane() non sia un metodo visibile da JPanel!!!

Ecco perchè ti dà errore.

Grazie, ora si compila. ma c'e' un altro errore quando eseguo il comando java:

java ShapeDraw per l'esattezza, che sarebbe il test class per ShapeDrawJFrame( l'ho cambiato). L'errore e':
"
C:\java>java ShapeDraw
Exception in thread "main" java.lang.NullPointerException
at ShapeDrawJFrame.<init>(ShapeDrawJFrame.java:37)
at ShapeDraw.main(ShapeDraw.java:10)"

Non capisco cosa devo fare.

Vi riporto i due codici corretti:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ShapeDrawJFrame extends JFrame {

private final int SHAPETYPES=3;
private int shapeType=0;
private String shapeTypes[]= {"Line","Oval", "Rectangle"};
private int numShapes=0;
private int XYValues[] = new int[4];
private Shape[] shapes = new Shape[100];
private JLabel label;
private JComboBox shapesComboBox;
private JCheckBox filled;
private Container container;
private JPanel lowerRow;
private JButton button;

public ShapeDrawJFrame() {


addMouseListener( new MouseClickHandler());
getContentPane().setBackground(new Color(255,255,255));

lowerRow = new JPanel();
label = new JLabel("You have to select the type of shape to draw");
lowerRow.add(label);
button = new JButton("UNDO");
lowerRow.add(button);



shapesComboBox = new JComboBox(shapeTypes);
shapesComboBox.setSelectedIndex(0);
lowerRow.add(shapesComboBox);
container.add(lowerRow, BorderLayout.SOUTH); setSize(600,600); setVisible( true );
}

public void paint( Graphics g) {
super.paint(g);
for (int sp=0;sp< shapes.length ; sp++) {
if(shapes[sp]!=null) {
shapes[sp].draw(g);
}}}

public void createShape(int index) {

numShapes++;
switch (index) {
case 0: shapes[numShapes] = new Line(XYValues); break;
case 1: shapes[numShapes] = new Oval(XYValues); break;
case 2: shapes[numShapes] = new Rectangle(XYValues); break;
}}

private class MouseClickHandler extends MouseAdapter {
public void mousePressed (MouseEvent event) {
XYValues[0] = event.getX();
XYValues[1] = event.getY(); }
}
public void mouseReleased (MouseEvent event) {
XYValues[2] = event.getX();
XYValues[3] = event.getY();
createShape(shapesComboBox.getSelectedIndex());
repaint();
}


}

**********

import javax.swing.JFrame;

public class ShapeDraw

{

//execute application
public static void main(String args[]) {

ShapeDrawJFrame shapeDrawJFrame = new ShapeDrawJFrame();
shapeDrawJFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

shapeDrawJFrame.setVisible( true );
}}


Grazie tante in anticipo!

[spv42]

L'errore è su questa linea:

container.add(lowerRow, BorderLayout.SOUTH);

ma il container non è stato inizializzato è null.

Prova a fare :

container = getContentPane() prima di quell'istruzione

P.S Quando posti il codice, includilo nei tag "[code]" e "chiudi [code]"

esempio:

 
public ShapeDrawJFrame() {


addMouseListener( new MouseClickHandler());
getContentPane().setBackground(new Color(255,255,255));

[mariade]

Originariamente inviato da spv42

L'errore è su questa linea:

container.add(lowerRow, BorderLayout.SOUTH);

ma il container non è stato inizializzato è null.

Prova a fare :

container = getContentPane() prima di quell'istruzione

P.S Quando posti il codice, includilo nei tag "[code]" e "chiudi [code]"

esempio:

 
public ShapeDrawJFrame() {


addMouseListener( new MouseClickHandler());
getContentPane().setBackground(new Color(255,255,255));

Ho corretto cosi':

addMouseListener( new MouseClickHandler());
container = getContentPane()
container.setBackground(new Color(255,255,255));

ma l'errore non va via...

[spv42]

Originariamente inviato da mariade

Ho corretto cosi':

addMouseListener( new MouseClickHandler());
container = getContentPane()
container.setBackground(new Color(255,255,255));

ma l'errore non va via...

lo stesso errore?

prova a mettere un punto e virgola container = getContentPane();

[mariade]

Originariamente inviato da spv42

lo stesso errore?

prova a mettere un punto e virgola container = getContentPane();

nulla...uguale.
Grazie tante cmq!

[spv42]

A me quelle due classi non le compila neanche.

Ma ci mancano altri pezzi?

[mariade]

si, ci mancano:
1.


import java.awt.*; import javax.swing.*;

public abstract class Shape {

private int x1, x2, y1, y2; private boolean isFilled = false;
public Shape () {setX1(0); setY1(0); setX2(0); setY2(0);}
public Shape (int val1, int val2, int val3, int val4) { setX1(val1); setY1(val2); setX2(val3); setY2(val4);}
public Shape (int val1,int val2,int val3,int val4,boolean fill) {setX1(val1); setY1(val2);setX2(val3);setY2(val4); isFilled = fill;}
public Shape (int vals[]) {setX1(vals[0]); setY1(vals[1]); setX2(vals[2]); setY2(vals[3]); }
public Shape (int vals[], boolean fill) {setX1(vals[0]); setY1(vals[1]); setX2(vals[2]); setY2(vals[3]); isFilled = fill; }
public void setX1(int val) {x1 = ( val >= 0 ? val : 0 );} public void setX2(int val) {x2 = ( val >= 0 ? val : 0 );}
public void setY1(int val) {y1 = ( val >= 0 ? val : 0 );} public void setY2(int val) {y2 = ( val >= 0 ? val : 0 );}
public void setFilled(boolean fill) {isFilled=fill;}
public int getX1() {return x1;} public int getX2() {return x2;}
public int getY1() {return y1;} public int getY2() {return y2;}
public boolean getFilled() {return isFilled;}
public abstract void draw (Graphics g);

}

2.

import java.awt.*; import javax.swing.*;

public abstract class BoundedShape extends Shape {
public BoundedShape () {super();}
public BoundedShape (int val1, int val2, int val3, int val4) {super(val1,val2,val3,val4);}
public BoundedShape (int val1, int val2, int val3, int val4, boolean fill) {super(val1,val2,val3,val4, fill);}
public BoundedShape (int val[]) {super(val); }
public BoundedShape (int val[], boolean fill) {super(val, fill); }
public int getUpperLeftX() { return Math.min(getX1(), getX2()); }
public int getUpperLeftY() { return Math.min(getY1(), getY2()); }
public int getWidth() {return Math.abs(getX1() - getX2());}
public int getHeight() {return Math.abs(getY1() - getY2());}
}

3.

import java.awt.*; import javax.swing.*;
public class Line extends Shape {
public Line () {super();}
public Line (int val1, int val2, int val3, int val4) {super(val1,val2,val3,val4); }
public Line (int val[]) {super(val);}
public void draw (Graphics g) {g.drawLine(getX1(),getY1(),getX2(), getY2()); }
}

4.

import java.awt.*; import javax.swing.*;
public class Oval extends BoundedShape {
public Oval () {super();}
public Oval (int val1, int val2, int val3, int val4) {super(val1,val2,val3,val4);}
public Oval (int val1, int val2, int val3, int val4, boolean fill) {super(val1,val2,val3,val4, fill);}
public Oval (int val[]) {super(val);}
public Oval (int val[], boolean fill) {super(val, fill);}
public void draw (Graphics g) {
if(getFilled())
g.drawOval(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight());
else
g.fillOval(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight());
}
}

5.

import java.awt.*; import javax.swing.*;
public class Rectangle extends BoundedShape {
public Rectangle () {super();}
public Rectangle (int val1, int val2, int val3, int val4) {super(val1,val2,val3,val4);}
public Rectangle (int val1, int val2, int val3, int val4, boolean fill) {super(val1,val2,val3,val4, fill);}
public Rectangle (int val[]) {super(val);}
public Rectangle (int val[], boolean fill) {super(val, fill);}
public void draw (Graphics g) {
if(getFilled())
g.drawRect(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight());
else
g.fillRect(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight());
}
}

[spv42]

Originariamente inviato da mariade

si, ci mancano:
1.


import java.awt.*; import javax.swing.*;

public abstract class Shape {

private int x1, x2, y1, y2; private boolean isFilled = false;
public Shape () {setX1(0); setY1(0); setX2(0); setY2(0);}
public Shape (int val1, int val2, int val3, int val4) { setX1(val1); setY1(val2); setX2(val3); setY2(val4);}
public Shape (int val1,int val2,int val3,int val4,boolean fill) {setX1(val1); setY1(val2);setX2(val3);setY2(val4); isFilled = fill;}
public Shape (int vals[]) {setX1(vals[0]); setY1(vals[1]); setX2(vals[2]); setY2(vals[3]); }
public Shape (int vals[], boolean fill) {setX1(vals[0]); setY1(vals[1]); setX2(vals[2]); setY2(vals[3]); isFilled = fill; }
public void setX1(int val) {x1 = ( val >= 0 ? val : 0 );} public void setX2(int val) {x2 = ( val >= 0 ? val : 0 );}
public void setY1(int val) {y1 = ( val >= 0 ? val : 0 );} public void setY2(int val) {y2 = ( val >= 0 ? val : 0 );}
public void setFilled(boolean fill) {isFilled=fill;}
public int getX1() {return x1;} public int getX2() {return x2;}
public int getY1() {return y1;} public int getY2() {return y2;}
public boolean getFilled() {return isFilled;}
public abstract void draw (Graphics g);

}

2.

import java.awt.*; import javax.swing.*;

public abstract class BoundedShape extends Shape {
public BoundedShape () {super();}
public BoundedShape (int val1, int val2, int val3, int val4) {super(val1,val2,val3,val4);}
public BoundedShape (int val1, int val2, int val3, int val4, boolean fill) {super(val1,val2,val3,val4, fill);}
public BoundedShape (int val[]) {super(val); }
public BoundedShape (int val[], boolean fill) {super(val, fill); }
public int getUpperLeftX() { return Math.min(getX1(), getX2()); }
public int getUpperLeftY() { return Math.min(getY1(), getY2()); }
public int getWidth() {return Math.abs(getX1() - getX2());}
public int getHeight() {return Math.abs(getY1() - getY2());}
}

3.

import java.awt.*; import javax.swing.*;
public class Line extends Shape {
public Line () {super();}
public Line (int val1, int val2, int val3, int val4) {super(val1,val2,val3,val4); }
public Line (int val[]) {super(val);}
public void draw (Graphics g) {g.drawLine(getX1(),getY1(),getX2(), getY2()); }
}

4.

import java.awt.*; import javax.swing.*;
public class Oval extends BoundedShape {
public Oval () {super();}
public Oval (int val1, int val2, int val3, int val4) {super(val1,val2,val3,val4);}
public Oval (int val1, int val2, int val3, int val4, boolean fill) {super(val1,val2,val3,val4, fill);}
public Oval (int val[]) {super(val);}
public Oval (int val[], boolean fill) {super(val, fill);}
public void draw (Graphics g) {
if(getFilled())
g.drawOval(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight());
else
g.fillOval(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight());
}
}

5.

import java.awt.*; import javax.swing.*;
public class Rectangle extends BoundedShape {
public Rectangle () {super();}
public Rectangle (int val1, int val2, int val3, int val4) {super(val1,val2,val3,val4);}
public Rectangle (int val1, int val2, int val3, int val4, boolean fill) {super(val1,val2,val3,val4, fill);}
public Rectangle (int val[]) {super(val);}
public Rectangle (int val[], boolean fill) {super(val, fill);}
public void draw (Graphics g) {
if(getFilled())
g.drawRect(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight());
else
g.fillRect(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight());
}
}

azz

[spv42]

Cosi a me Funziona

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ShapeDrawJFrame extends JFrame {

	private final int SHAPETYPES=3;
	private int shapeType=0;
	private String shapeTypes[]= {"Line","Oval", "Rectangle"};
	private int numShapes=0;
	private int XYValues[] = new int[4];
	private Shape[] shapes = new Shape[100];
	private JLabel label;
	private JComboBox shapesComboBox;
	private JCheckBox filled;
	private Container container;
	private JPanel lowerRow;
	private JButton button;
	
	public ShapeDrawJFrame() {
	
	
		addMouseListener( new MouseClickHandler());
		container = getContentPane();
		container.setBackground(new Color(255,255,255));
		
		lowerRow = new JPanel();
		label = new JLabel("You have to select the type of shape to draw");
		lowerRow.add(label);
		button = new JButton("UNDO");
		lowerRow.add(button);
		shapesComboBox = new JComboBox(shapeTypes);
		shapesComboBox.setSelectedIndex(0);
		lowerRow.add(shapesComboBox);
		container.add(lowerRow, BorderLayout.SOUTH); 
		setSize(600,600); 
		setVisible( true );
	}
	
	public void paint( Graphics g) {
		super.paint(g);
		for (int sp=0;sp< shapes.length ; sp++) {
			if(shapes[sp]!=null) {
				shapes[sp].draw(g);
			}
		}
	}
	
	public void createShape(int index) {
	
		numShapes++;
		switch (index) {
			case 0: shapes[numShapes] = new Line(XYValues); break;
			case 1: shapes[numShapes] = new Oval(XYValues); break;
			case 2: shapes[numShapes] = new Rectangle(XYValues); break;
		}
	}
	
	private class MouseClickHandler extends MouseAdapter {
		public void mousePressed (MouseEvent event) {
				XYValues[0] = event.getX();
				XYValues[1] = event.getY(); 
			}
		public void mouseReleased (MouseEvent event) {
			XYValues[2] = event.getX();
			XYValues[3] = event.getY();
			createShape(shapesComboBox.getSelectedIndex());
			repaint();
		}
	}
		


}

prova con questa, al posto della tua.

[mariade]

GRAZIE MILLE!!! ANCHE A ME FUNZIONA ORA CON LE TUE CORREZIONI.

ORA PERO' , DATO CHE SI TRATTA DI UN PROGETTO SCOLASTICO, DEVO FINIRE DI COMPLETARLO, NEL CASO AVESSI PROBLEMI...TI FACCIO SAPERE

cIAO

[spv42]

Di Nulla.

Siamo qui apposta

Ok, Fammi sapere.

[mariade]

Ciao,

come detto prima, sto cercando di completare l'applicazione:

1. devo aggiungere piu' forme (Arcs, polygons and polylines).
2. devo aggiungere un ComboBox per scegliere i colori.
3. devo aggiungere un CheckBox per selezionare se la figura la voglio piena o no.
ti ggiungo quello che ho fatto fino ad adesso, volevo piu' o meno un aiuto, una guida per aggiungere queste ultime cose.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ShapeDrawJFrame extends JFrame {

private final int SHAPETYPES=3;
private int shapeType=0;
private String shapeTypes[]= {"Line","Oval", "Rectangle", "Arcs", "Polygons",};
private int numShapes=0;
private int XYValues[] = new int[4];
private MyShape[] shapes = new Shape[100];
private JCheckBox filled;
private boolean isFilled;
private JComboBox shapesComboBox;
private JComboBox ColorChoice;
private Container container;
private JPanel lowerRow;
private JButton button;

public ShapeDrawJFrame() {


addMouseListener( new MouseClickHandler());
container = getContentPane();
container.setBackground(new Color(255,255,255));


lowerRow = new JPanel();
shapesComboBox = new JComboBox(shapeTypes);
shapesComboBox.setSelectedIndex(0);
lowerRow.add(shapesComboBox);
colorChoice = new JComboBox();
colorChoice.setSelectedIndex(0);
colorChoice.addItem("Black");
colorChoice.addItem("Red");
colorChoice.addItem("Green");
colorChoice.addItem("Blue");
colorChoice.addItem("Cyan");
colorChoice.addItem("Magenta");
colorChoice.addItem("Yellow");
colorChoice.addItem("White");
colorChoice.setBackground(Color.white);
lowerRow.add(colorChoice);

filled = new JCheckBox(boolean.isFilled);
lowerRow.add(filled);

button = new JButton("UNDO");
lowerRow.add(button);

container.add(lowerRow, BorderLayout.SOUTH);
setSize(600,600);
setVisible( true );
}

public void paint( Graphics g) {
super.paint(g);
for (int sp=0;sp< shapes.length ; sp++) {
if(shapes[sp]!=null) {
shapes[sp].draw(g);
}
}
}

public void createShape(int index) {

numShapes++;
switch (index) {
case 0: shapes[numShapes] = new Line(XYValues); break;
case 1: shapes[numShapes] = new Oval(XYValues); break;
case 2: shapes[numShapes] = new Rectangle(XYValues); break;
case 3: shapes[numShapes] = new Arcs(XYValues); break;
case 4: shapes[numShapes] = new Polygons(XYValues); break;
}
}

private class MouseClickHandler extends MouseAdapter {
public void mousePressed (MouseEvent event) {
XYValues[0] = event.getX();
XYValues[1] = event.getY();
}
public void mouseReleased (MouseEvent event) {
XYValues[2] = event.getX();
XYValues[3] = event.getY();
createShape(shapesComboBox.getSelectedIndex());
repaint();
}
}



}

[spv42]

Ok, stai andando avanti bene.

Però l'applicazione devi farla tu, così avrai più soddisfazione quando avrai finito.

P.P.S Quando posti il codice, includilo nei tag "[code]" e "chiudi [code]"

[mariade]

Originariamente inviato da spv42

Ok, stai andando avanti bene.

Però l'applicazione devi farla tu, così avrai più soddisfazione quando avrai finito.

P.P.S Quando posti il codice, includilo nei tag "[code]" e "chiudi [code]"

Ciao,

sto andando avanti nel progetto. Ho creato cosi' il codice per disegnare l'arco. Non so se e' giusto, soprattutto nella parte del startAngle e del arcAngle, ma nel momento in cui lo compilo mi vien fuori questo errore:

C:\java\project>javac Arc.java
Error occurred during initialization of VM
java.lang.OutOfMemoryError: unable to create new native thread

Non capisco che significa. Aggiungo che ho cambiato la superclass da Shape in MyShape come il professore mi chiedeva.

import java.awt.*; import javax.swing.*;

public abstract class Arc extends MyShape {
public Arc () {super();}
public Arc (int val1, int val2, int val3, int val4, int val5, int val6) {super(val1,val2,val3,val4,val5,val6);}
public Arc (int val1, int val2, int val3, int val4, int val5, int val6, boolean fill) {

super(val1,val2,val3,val4,val5,val6,fill);}


public Arc (int val[]) {super(val); }
public Arc (int val[], boolean fill) {super(val, fill); }
public int getUpperLeftX() { return Math.min(getX1(), getX2()); }
public int getUpperLeftY() { return Math.min(getY1(), getY2()); }
public int getWidth() {return Math.abs(getX1() - getX2());}
public int getHeight() {return Math.abs(getY1() - getY2());}
public int getStartAngle() {return Math.min(getX3, getY3);
public int getArcAngle() {return Math.min(getX4, getY4);

public void draw (Graphics g) {
if(getFilled())
g.drawArc(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight(),getStartAngle(),getArcAngle());
else
g.fillRect(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight(),getStartAngle(),getArcAngle());
}
}

[spv42]

Ti sei dimenticato qualche parentesi graffa.

prova con questa:

import java.awt.*; 
import javax.swing.*;

public abstract class Arc extends MyShape {
	public Arc () {super();}
	public Arc (int val1, int val2, int val3, int val4, int val5, int val6) {super(val1,val2,val3,val4,val5,val6);}
	public Arc (int val1, int val2, int val3, int val4, int val5, int val6, boolean fill) {
	
	super(val1,val2,val3,val4,val5,val6,fill);}
	
	
	public Arc (int val[]) {super(val); }
	public Arc (int val[], boolean fill) {super(val, fill); }
	public int getUpperLeftX() { return Math.min(getX1(), getX2()); }
	public int getUpperLeftY() { return Math.min(getY1(), getY2()); }
	public int getWidth() {return Math.abs(getX1() - getX2());}
	public int getHeight() {return Math.abs(getY1() - getY2());}
	public int getStartAngle() {return Math.min(getX3, getY3);}
	public int getArcAngle() {return Math.min(getX4, getY4);}
	
	public void draw (Graphics g) {
		if(getFilled())
			g.drawArc(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight(),getStartAngle(),getArcAngle());
		else
			g.fillRect(getUpperLeftX(),getUpperLeftY(),getWidth(),getHeight(),getStartAngle(),getArcAngle());
		}
}

[mariade]

ora esce un altro errore:

C:\java\project>javac Arc.java
Error occurred during initialization of VM
Could not reserve enough space for object heap

sai cosa significa?

[spv42]

Che la JVM non riesce ad allocare la quantità richiesta di Memoria Heap.

Ma è strano che te lo dia in fase di compilazione.

[mariade]

Originariamente inviato da spv42

Che la JVM non riesce ad allocare la quantità richiesta di Memoria Heap.

Ma è strano che te lo dia in fase di compilazione.

Ora sono a lavoro, dopo provo a casa e vediamo un po' se mi da lo stesso errore.
Grazie tante. Una curiosita', la parte di codice di Arc per acquisire lo startAngle e arcAngle e' corretta, secondo te?