帮帮忙！ 怎么给JPanel 加上 JScrollPane！！！！

[dds11one]

public class test extends JFrame{
	private static final long serialVersionUID = 5699328341463955028L;
	private JScrollPane jsp = null;
	private JPanel jp = null;
	private JPanel jpMainList2 = null;
	private JTextArea jta = null;
	
	
	private JScrollPane getJsp(){
		if(jsp == null){
			jsp = new JScrollPane();
			jsp.setLayout(null);
			jsp.setAutoscrolls(true);
			jsp.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
			jsp.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
			jsp.add(getjp());
			jsp.setSize(500,600);
			jsp.setBackground(Color.red);
		}
		return jsp;
	}
	
	private JPanel getjp(){
		if(jp == null){
			jp = new JPanel();
			jp.setLayout(null);
			jp.add(getjta());
			jp.setLocation(50, 50);
			jp.setSize(1000,1000);
			jp.setBackground(Color.white);
			
		}
		return jp;
	}
	
	private JTextArea getjta(){
		if(jta == null){
			jta = new JTextArea();
			jta.setSize(1500, 1500);
			jta.setBackground(Color.CYAN);
		}
		return jta;
	}
	
	public test(){
		this.setLayout(null);
		this.add(getJsp());
		this.setExtendedState(Frame.MAXIMIZED_BOTH);
		this.setVisible(true);
	}
	
	public static void main(String[] args){
		new test();
	}
}

Jpanel 的大小 已经超出 JScrollPane 的大小了 ，怎么滚动条没有用？
应该怎么做？帮帮忙！

[Inhibitory]

 private JScrollPane getJsp(){
        if(jsp == null){
            jsp = new JScrollPane(getjp());
            jsp.setLayout(null);
            jsp.setAutoscrolls(true);
            jsp.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
            jsp.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
            //jsp.add(getjp()); 或者是setViewport(getjp());
            jsp.setSize(500,600);
            jsp.setBackground(Color.red);
        }
        return jsp;
    }

[dds11one]

[Quote=引用 1 楼 inhibitory 的回复:]
Java code
private JScrollPane getJsp(){
if(jsp == null){
jsp = new JScrollPane(getjp());
jsp.setLayout(null);
jsp.setAutoscrolls(true);
j……
[/Quote]

没有用啊 请说清楚点

[Inhibitory]

出错是因为你使用了 setLayout(null);

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Frame;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.ScrollPaneConstants;

public class test extends JFrame {
    private static final long serialVersionUID = 5699328341463955028L;
    private JScrollPane jsp = null;
    private JPanel jp = null;
    private JPanel jpMainList2 = null;
    private JTextArea jta = null;

    private JScrollPane getJsp() {
        if (jsp == null) {
            jsp = new JScrollPane(getjp());
            //jsp.setLayout(null);
            jsp.setAutoscrolls(true);
            jsp.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
            jsp.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
            //jsp.add(getjp());
            jsp.setSize(500, 600);
            jsp.setBackground(Color.red);
        }
        return jsp;
    }

    private JPanel getjp() {
        if (jp == null) {
            jp = new JPanel();
            //jp.setLayout(null);
            jp.setLayout(new BorderLayout());
            jp.add(getjta());
            jp.setLocation(50, 50);
            jp.setSize(1000, 1000);
            jp.setBackground(Color.white);

        }
        return jp;
    }

    private JTextArea getjta() {
        if (jta == null) {
            jta = new JTextArea();
            jta.setSize(1500, 1500);
            jta.setBackground(Color.CYAN);
        }
        return jta;
    }

    public test() {
        this.setLayout(null);
        this.add(getJsp());
        this.setExtendedState(Frame.MAXIMIZED_BOTH);
        this.setVisible(true);
    }

    public static void main(String[] args) {
        new test();
    }
}

[dds11one]

[Quote=引用 3 楼 inhibitory 的回复:]
出错是因为你使用了 setLayout(null);

Java code
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Frame;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSc……
[/Quote]



还是你行啊 ，麻烦写个例子看看啊 ！ 谢谢

[dds11one]

还是不行啊 ，麻烦写个例子看看啊 ！ 谢谢

[huntor]

JTextArea textcomponent = new JTextArea();
textcomponent.set...;
JScrollPane scollpane = new JScrollPane(textcomponent,22,32);

[Inhibitory]

import java.awt.Dimension;
import java.awt.Toolkit;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

@SuppressWarnings("serial")
public class Test extends JPanel {
    @Override
    public Dimension getPreferredSize() {
        return new Dimension(600, 600); // 这个值只是推荐值，并不一定会使用到
    }

    private static void createGuiAndShow() {
        JFrame frame = new JFrame("");
        
        JPanel panel = new JPanel();
        panel.add(new JButton("....Button...."));
        panel.setPreferredSize(new Dimension(600, 600)); // 这里设置才有用
        JScrollPane scroller = new JScrollPane(panel);
        frame.getContentPane().add(scroller);

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        int sw = Toolkit.getDefaultToolkit().getScreenSize().width;
        int sh = Toolkit.getDefaultToolkit().getScreenSize().height;
        int w = 400;
        int h = 400;
        int x = (sw - w) / 2;
        int y = (sh - h) / 2 - 40;
        x = x > 0 ? x : 0;
        y = y > 0 ? y : 0;
        frame.setBounds(x, y, w, h);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        createGuiAndShow();
    }
}

[dds11one]

[Quote=引用 7 楼 inhibitory 的回复:]
Java code
import java.awt.Dimension;
import java.awt.Toolkit;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

@SuppressWarn……
[/Quote]

搞定了，谢谢 还是布局的问题！