[JAVA]: Creare JTextArea con scroll

[bako]

Salve gente,
siccome sono stufo di fare tutte le volte la textarea e poi aggiungerci lo scroll, volveo fare una classe ad hoc.

import java.awt.Rectangle;

import javax.swing.JScrollPane;
import javax.swing.JTextArea;


public class jTextAreaScroll extends JTextArea {
	
	public JScrollPane jsp=null;
	
	public jTextAreaScroll(int x, int y, int w, int h) {
		super();
		this.setBounds(new Rectangle(x,y,w,h));
		this.setWrapStyleWord(true);
		jsp = new JScrollPane(this);
		jsp.setBounds(this.getX(),this.getY(),this.getWidth(),this.getHeight());
		
		}
}

	jtp = new jTextAreaScroll(10,25,300,300);
	jPanel.add(jtp, null);

ma la text area viene creata, mentre la scroll nulla di nulla...
dove sta l'errore?

[floyd]

l'errore sta nel fatto che lo scroll pane lo tieni nascosto nella classe
devi estendere JScrollPane

[bako]

Originariamente inviato da floyd
l'errore sta nel fatto che lo scroll pane lo tieni nascosto nella classe
devi estendere JScrollPane

:master:
invece che estendere la textarea estendo la scroll pane?

[floyd]

sì

[bako]

Originariamente inviato da floyd
sì

c'ho provato ma come??

import java.awt.Rectangle;
import java.awt.ScrollPane;

import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class jTextScroll extends ScrollPane {

	public JTextArea jta=null;
	
	public jTextScroll(int x, int y, int w, int h) {
		this.setBounds(new Rectangle(x,y,w,h));
	        jta = new JTextArea();
		jta.setBounds(new Rectangle(x,y,w,h));

		}
}

e poi l'aggiungo come l'altra..
ma nn va, disegna robe strane..

[floyd]

private JTextArea jta = new JTextArea();
public jTextScroll(int x, int y, int w, int h) {
  super(jta);
  ...
}

[bako]

Originariamente inviato da floyd

private JTextArea jta = new JTextArea();
public jTextScroll(int x, int y, int w, int h) {
  super(jta);
  ...
}

nn va

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
	The field jTextScroll.jta is not visible

[floyd]

giusto, non si può usare una proprietà prima dell'esecuzione del costruttore della super classe

  class jTextScroll extends JScrollPane {
    private JTextArea jta = new JTextArea();
    public jTextScroll(int x, int y, int w, int h) {
      setViewportView(jta);
      jta.setBounds(new java.awt.Rectangle(x,y,w,h));
    }
  }

[bako]

allora:

jTextScroll.java

package provaGui;

import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public   class jTextScroll extends JScrollPane {
    private JTextArea jta = new JTextArea();
    public jTextScroll(int x, int y, int w, int h) {
      setViewportView(jta);
      jta.setBounds(new java.awt.Rectangle(x,y,w,h));
    }
  }

Gui.java

package provaGui;

import javax.swing.JPanel;
import javax.swing.JFrame;

public class Gui extends JFrame {

	private static final long serialVersionUID = 1L;

	private JPanel jContentPane = null;

	/**
	 * This is the default constructor
	 */
	public Gui() {
		super();
		initialize();
	}

	/**
	 * This method initializes this
	 * 
	 * @return void
	 */
	private void initialize() {
		this.setSize(300, 200);
		this.setContentPane(getJContentPane());
		this.setTitle("JFrame");
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.show();
	}

	/**
	 * This method initializes jContentPane
	 * 
	 * @return javax.swing.JPanel
	 */
	private JPanel getJContentPane() {
		if (jContentPane == null) {
			jContentPane = new JPanel();
			jContentPane.setLayout(null);
			jContentPane.add(new jTextScroll(0,0,100,100),null);
		}
		return jContentPane;
	}

}

GuiMain.java

package provaGui;

public class GuiMain {

	public static void main (String argv[]){
		new Gui();
	}
}

risulatao:

Exception in thread "main" java.lang.NullPointerException
	at javax.swing.text.PlainView.getLineWidth(Unknown Source)
	at javax.swing.text.PlainView.getPreferredSpan(Unknown Source)
	at javax.swing.plaf.basic.BasicTextUI$RootView.getPreferredSpan(Unknown Source)
	at javax.swing.plaf.basic.BasicTextUI.getPreferredSize(Unknown Source)
	at javax.swing.plaf.basic.BasicTextAreaUI.getPreferredSize(Unknown Source)
	at javax.swing.JComponent.getPreferredSize(Unknown Source)
	at javax.swing.JTextArea.getPreferredSize(Unknown Source)
	at javax.swing.ScrollPaneLayout.layoutContainer(Unknown Source)
	at java.awt.Container.layout(Unknown Source)
	at java.awt.Container.doLayout(Unknown Source)
	at java.awt.Container.validateTree(Unknown Source)
	at java.awt.Container.validateTree(Unknown Source)
	at java.awt.Container.validateTree(Unknown Source)
	at java.awt.Container.validateTree(Unknown Source)
	at java.awt.Container.validateTree(Unknown Source)
	at java.awt.Container.validate(Unknown Source)
	at java.awt.Window.show(Unknown Source)
	at provaGui.Gui.initialize(Gui.java:31)
	at provaGui.Gui.<init>(Gui.java:18)
	at provaGui.GuiMain.main(GuiMain.java:6)

[floyd]

at provaGui.Gui.initialize(Gui.java:31)
che riga è la 31?