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自动刷新jtable提取集合数据

发布于 2024-11-08 20:35:07 字数 6409 浏览 0 评论 0原文

我是java编程的初学者。

我正在尝试制作一个读取集合集 hashSet 的 JTable，并在每次更改集合时刷新，还想在表所在的 JPanel 上每 3 秒重新绘制一次自动刷新（这在原始程序中有效）。 另外，类 Mats 会随着时间的推移更改布尔值，我想根据集合中该垫子中的 Mats.take 值来更改其在 JTable 中扭动的 Mats.name 的颜色，这就是自动刷新的原因。

这是表的示例，它从头开始重新制作表，每次添加新行都会抛出 java.lang.NullPointerException。 我根本不明白为什么？ 感谢您提前提供帮助

public class Table extends JFrame {
    private static JTable table;
    private static JButton addbuttin;
    private static TableModel model;
    private static Set<Mats> set = null;

    public static String colorString(String str, Mats a) {
        if (a.getTake().equals(new Boolean(true))) {
            return "<html><body><font color=red>" + str
                    + "</font></body></html>";
        } else {
            return "<html><body><font color=blue>" + str
                    + "</font></body></html>";
        }
    }

    public static void main(String[] argv) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        addbuttin = new JButton("Dodaj");
        Mats a = new Mats(10, 10, 5, "WOOD", true);
        Mats b = new Mats(10, 12, 5, "WOOD", false);

        set = new HashSet<Mats>();
        set.add(a);
        set.add(b);

        addbuttin.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent arg0) {
                Mats c = new Mats(10, 12, 6, "WOOD", true);
                set.add(c);
            }
        });

        JPanel p = new JPanel();

        model = new DefaultTableModel() {
            public boolean isCellEditable(int rowIndex, int vColIndex) {
                return false;
            }
        };
/**here is java.lang.NullPointerException*/
        table.getModel().addTableModelListener(new TableModelListener() {

            @Override
            public void tableChanged(TableModelEvent e) {
                if (e.equals(TableModelEvent.INSERT)) {
                    model = new DefaultTableModel();
                    addColumns();
                    adddata(set);
                }

            }
        });
        addColumns();
        adddata(set);
        table = new JTable(model);

        JScrollPane scrollPane = new JScrollPane(table,
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);

        p.add(scrollPane, BorderLayout.CENTER);
        p.add(addbuttin, BorderLayout.EAST);
        p.setSize(500, 400);

        frame.add(p);
        frame.setSize(600, 600);
        frame.setVisible(true);

    }

    private static void addColumns() {
        ((DefaultTableModel) model).addColumn("NAME");
    }

    private static void adddata(Set<Mats> set) {
        for (Iterator iterator = set.iterator(); iterator.hasNext();) {
            Mats mats = (Mats) iterator.next();

            String n = colorString(mats.getName(), mats);
            ((DefaultTableModel) model).insertRow(model.getRowCount(), new Object[] { n });
        }
    }

}

这是 Mats 类简化的

public class Mats implements Comparable<Mats> {


    private String name;
    private Boolean take;

    /**
     *
     */
    public Mats() {
    }

    /**
     * 
     * @param name
     * @param uzet
     */
    public Mats(String name, boolean take) {

        this.name = name.toUpperCase();
        this.take = take;
        taken();
    }

    /**
     * 
     * @param Material
     */
    public Mats(Mats Material) {
                this.name = Material.getName().toUpperCase();
        this.take = Material.getTake();
        Material.taken();
    }

        /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @param name
     *            the name to set
     */
    public void setName(String name) {
        this.name = name.toUpperCase();
    }

    /**
     * @param take
     *            the take to set
     */
    public void setTake(Boolean take) {
        this.take = take;
    }

    /**
     * @return the take
     */
    public Boolean getTake() {
        return take;
    }



    /**
     * 
     * @return
     */
    @Override
    public String toString() {
        return "Material: ".toUpperCase() + getName() + "\n";
    }

    /**
     * 
     * @param obj
     * @return
     */
    @Override
    public boolean equals(Object obj) {
        Mats a = (Mats) obj;
        if (obj == null) {
            return false;
        }
        if (a.getName() == this.getName()) {
            return true;
        }
        return false;
    }

    /**
     * 
     * @return
     */
    @Override
    public int hashCode() {
        int hash = 3;
        hash = 83 * hash + this.getX();
        hash = 83 * hash + this.getY();
        hash = 83 * hash
                + (this.getName() != null ? this.getName().hashCode() : 0);
        return hash;
    }

    /**
     *
     */
    public void taken() {
        MatRespawn s = new MatRespawn(1000, take);
        s.start();
    }

    @Override
    public int compareTo(Mats o) {
        Integer a = this.getName();
        if (a.compareTo(o.getName()) != 0)
            return a.compareTo(o.getName());
        return 0;
    }
}

MatRespawn 类，它更改了 Mats.take

public class MatRespawn extends Thread {
    private int time;
    private Boolean taken;

    public MatRespawn(int time, Boolean take) {
        this.time = time;
        this.taken = take;
    }

    public int getTime() {
        return time;
    }

    public void setTime(int time) {
        this.time = time;
    }

    public Boolean getTaken() {
        return taken;
    }

    public void setTaken(Boolean taken) {
        this.taken = taken;
    }

    @Override
    public void run() {
        try {
            while (true) {
                if (taken.equals(new Boolean(true))) {
                    sleep(time * 10);
                    //JOptionPane.showMessageDialog(null, "dostupnost: " + taken);
                    taken = false;
                }

                sleep(time);
                //JOptionPane.showMessageDialog(null, "dostupnost: " + taken);
                taken = true;

            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
原文

I am a begginer with java programming.

I am trying to make a JTable that reads collection set hashSet, and refreshes eachtime set is changed, also want to make autorefresh every 3 sec repaint on JPanel where table will be on (which works in original program).
Also Class Mats changes Boolean take over time, i want to change color its writhing Mats.name in JTable depending on the value Mats.take in that mat in set which is the reason for autorefresh.

This is a sample for table its remakeing table from scrach with each time new line is added throws java.lang.NullPointerException.
I simply do not see why?
Thx for the help in advance

public class Table extends JFrame {
    private static JTable table;
    private static JButton addbuttin;
    private static TableModel model;
    private static Set<Mats> set = null;

    public static String colorString(String str, Mats a) {
        if (a.getTake().equals(new Boolean(true))) {
            return "<html><body><font color=red>" + str
                    + "</font></body></html>";
        } else {
            return "<html><body><font color=blue>" + str
                    + "</font></body></html>";
        }
    }

    public static void main(String[] argv) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        addbuttin = new JButton("Dodaj");
        Mats a = new Mats(10, 10, 5, "WOOD", true);
        Mats b = new Mats(10, 12, 5, "WOOD", false);

        set = new HashSet<Mats>();
        set.add(a);
        set.add(b);

        addbuttin.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent arg0) {
                Mats c = new Mats(10, 12, 6, "WOOD", true);
                set.add(c);
            }
        });

        JPanel p = new JPanel();

        model = new DefaultTableModel() {
            public boolean isCellEditable(int rowIndex, int vColIndex) {
                return false;
            }
        };
/**here is java.lang.NullPointerException*/
        table.getModel().addTableModelListener(new TableModelListener() {

            @Override
            public void tableChanged(TableModelEvent e) {
                if (e.equals(TableModelEvent.INSERT)) {
                    model = new DefaultTableModel();
                    addColumns();
                    adddata(set);
                }

            }
        });
        addColumns();
        adddata(set);
        table = new JTable(model);

        JScrollPane scrollPane = new JScrollPane(table,
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);

        p.add(scrollPane, BorderLayout.CENTER);
        p.add(addbuttin, BorderLayout.EAST);
        p.setSize(500, 400);

        frame.add(p);
        frame.setSize(600, 600);
        frame.setVisible(true);

    }

    private static void addColumns() {
        ((DefaultTableModel) model).addColumn("NAME");
    }

    private static void adddata(Set<Mats> set) {
        for (Iterator iterator = set.iterator(); iterator.hasNext();) {
            Mats mats = (Mats) iterator.next();

            String n = colorString(mats.getName(), mats);
            ((DefaultTableModel) model).insertRow(model.getRowCount(), new Object[] { n });
        }
    }

}

This is Class Mats simplified

public class Mats implements Comparable<Mats> {


    private String name;
    private Boolean take;

    /**
     *
     */
    public Mats() {
    }

    /**
     * 
     * @param name
     * @param uzet
     */
    public Mats(String name, boolean take) {

        this.name = name.toUpperCase();
        this.take = take;
        taken();
    }

    /**
     * 
     * @param Material
     */
    public Mats(Mats Material) {
                this.name = Material.getName().toUpperCase();
        this.take = Material.getTake();
        Material.taken();
    }

        /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @param name
     *            the name to set
     */
    public void setName(String name) {
        this.name = name.toUpperCase();
    }

    /**
     * @param take
     *            the take to set
     */
    public void setTake(Boolean take) {
        this.take = take;
    }

    /**
     * @return the take
     */
    public Boolean getTake() {
        return take;
    }



    /**
     * 
     * @return
     */
    @Override
    public String toString() {
        return "Material: ".toUpperCase() + getName() + "\n";
    }

    /**
     * 
     * @param obj
     * @return
     */
    @Override
    public boolean equals(Object obj) {
        Mats a = (Mats) obj;
        if (obj == null) {
            return false;
        }
        if (a.getName() == this.getName()) {
            return true;
        }
        return false;
    }

    /**
     * 
     * @return
     */
    @Override
    public int hashCode() {
        int hash = 3;
        hash = 83 * hash + this.getX();
        hash = 83 * hash + this.getY();
        hash = 83 * hash
                + (this.getName() != null ? this.getName().hashCode() : 0);
        return hash;
    }

    /**
     *
     */
    public void taken() {
        MatRespawn s = new MatRespawn(1000, take);
        s.start();
    }

    @Override
    public int compareTo(Mats o) {
        Integer a = this.getName();
        if (a.compareTo(o.getName()) != 0)
            return a.compareTo(o.getName());
        return 0;
    }
}

Class MatRespawn which changes Mats.take

public class MatRespawn extends Thread {
    private int time;
    private Boolean taken;

    public MatRespawn(int time, Boolean take) {
        this.time = time;
        this.taken = take;
    }

    public int getTime() {
        return time;
    }

    public void setTime(int time) {
        this.time = time;
    }

    public Boolean getTaken() {
        return taken;
    }

    public void setTaken(Boolean taken) {
        this.taken = taken;
    }

    @Override
    public void run() {
        try {
            while (true) {
                if (taken.equals(new Boolean(true))) {
                    sleep(time * 10);
                    //JOptionPane.showMessageDialog(null, "dostupnost: " + taken);
                    taken = false;
                }

                sleep(time);
                //JOptionPane.showMessageDialog(null, "dostupnost: " + taken);
                taken = true;

            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

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评论（2）

枕梦 2024-11-15 20:35:07

当您调用 table.getModel() 时，您尚未调用 table = new JTable(model);
这意味着 table 仍然是 null，因此您会收到异常。尝试将构造 table 的行移动到访问它的行之前。

At the time you call table.getModel(), you haven't yet called table = new JTable(model);
That means that table is still null, and so you get an exception. Try moving the line that constructs table to before the line that accesses it.

回复 原文
歌枕肩 2024-11-15 20:35:07

发现还有什么问题

private static TableModel model;

后来我做了

model = new DefaultTableModel() {
            public boolean isCellEditable(int rowIndex, int vColIndex) {
                return false;
            }
        };

应该是
私有静态DefaultTableModel模型；

Found what else was wrong

private static TableModel model;

later i made

model = new DefaultTableModel() {
            public boolean isCellEditable(int rowIndex, int vColIndex) {
                return false;
            }
        };

Should have been
private static DefaultTableModel model;

回复 原文
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