【Java】JSliderの値が取得できません…。

Question

###前提・実現したいこと
初めまして。JavaでGUIの勉強をしている者です。
JSliderを使ってColorChooserに似た機能を自作しようと思い、JSliderの動作確認をしているところで詰まっています。
どこか簡単なところで躓いていると思うのですが、ご教授いただければ嬉しいです。

###発生している問題・エラーメッセージ
Jsliderの値が取得できず、困っています。
JsliderにaddChangeListenerは付けていて、StateChanged自体も動いているようなのですが…。

エラーメッセージ

長いです…。すみません。

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at ColorFrame.stateChanged(ColorFrame.java:60)
at javax.swing.JSlider.fireStateChanged(Unknown Source)
at javax.swing.JSlider$ModelListener.stateChanged(Unknown Source)
at javax.swing.DefaultBoundedRangeModel.fireStateChanged(Unknown Source)
at javax.swing.DefaultBoundedRangeModel.setRangeProperties(Unknown Source)
at javax.swing.DefaultBoundedRangeModel.setValueIsAdjusting(Unknown Source)
at javax.swing.JSlider.setValueIsAdjusting(Unknown Source)
at javax.swing.plaf.basic.BasicSliderUI$TrackListener.mouseDragged(Unknown Source)
at java.awt.Component.processMouseMotionEvent(Unknown Source)
at javax.swing.JComponent.processMouseMotionEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

###該当のソースコード

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

class ColorFrame extends JFrame implements ChangeListener{
    public JSlider rs;
    public Color initColor;
    public JTextField rn,bn,gn;
    
    public ColorFrame(){
	JSlider rs = new JSlider(JSlider.HORIZONTAL,0,255,0);
	rs.setPaintTicks(true);
	rs.setMajorTickSpacing(50);
	rs.setMinorTickSpacing(5);
	rs.setLabelTable(rs.createStandardLabels(50));
	rs.setPaintLabels(true);
	rs.addChangeListener(this);

	Color initColor =Color.pink;
	ColorPanel c = new ColorPanel(initColor);
	
	JPanel p = new JPanel();
	rn =new JTextField(1);
	bn =new JTextField(1);
	gn =new JTextField(1);
	p.setLayout(new GridLayout(3,2));
	p.add(rs); p.add(rn);
	this.add(p,BorderLayout.SOUTH);

        this.setTitle("TestFrame");
        
        this.add(c,BorderLayout.CENTER);
        this.pack();
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
	
    }
    
    public void stateChanged(ChangeEvent e){
	System.out.println(""+rs.getValue());
    }
    
    public static void main(String argv[]){
        new ColorFrame();
    }
}
class ColorPanel extends JPanel{
    public ColorPanel(){
        this(Color.white);
    }
    public ColorPanel(Color c){
        setColor(c);
        setPreferredSize(new Dimension(200,150));
    }
    public void setColor(Color c){
        setBackground(c);
    }
    public Color getColor(){
        return getBackground();
    }
}

###試したこと
System.out.println(""+rs.getValue())をSystem.out.print("ok")にしたところ、これは表示できました…。
よろしくお願いします…！

Answer 1

public ColorFrame(){
JSlider rs = new JSlider(JSlider.HORIZONTAL,0,255,0);
の部分を
public ColorFrame(){
rs = new JSlider(JSlider.HORIZONTAL,0,255,0);
にすれば動きます

Comments

[to_be.]

大変助かりました。ありがとうございます。