如何使用AbstractTableModel方法向JTable添加行? [英] How to add rows to JTable with AbstractTableModel method?

问题描述

我想向已初始化的JTable添加行.除了其他元素，我还有以下(相关)代码:

I want to add rows to an already initialized JTable. Apart from other elements I have the following (relevant) code:

import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;

class sscce extends JFrame {

private static final long serialVersionUID = 1L;    // Serial ID...

// Interface-Elemente erzeugen
Container content = getContentPane();

DefaultTableModel myAbstractTableModel = new DefaultTableModel () {
    private static final long serialVersionUID = 1L;    // whatever
    public String[] columnNames = {"AuftragNr", "Datum & Uhrzeit", "Von", "Nach", "erledigt?"};
    public Object[][] data = {{"156", "31.12.2012 - 10:39:31", "5/5", "205/39", new Boolean(false)}};

    public int getColumnCount() {
        return columnNames.length;
    }

    public int getRowCount() {
        return data.length;
    }

    public String getColumnName(int col) {
        return columnNames[col];
    }

    public Object getValueAt(int row, int col) {
        return data[row][col];
    }

    public Class getColumnClass(int c) {
        return getValueAt(0, c).getClass();
    }

    public boolean isCellEditable(int row, int col) {
        if (col != 4) {
            return false;
        } else {
            return true;
        }
    }

    public void setValueAt(Object value, int row, int col) {
        data[row][col] = value;
        fireTableCellUpdated(row, col);
    }
};

JTable auftragTable = new JTable(myAbstractTableModel);
JScrollPane tableScrollPane = new JScrollPane(auftragTable);
JButton auftragAenderungSpeichern = new JButton("speichern");

public sscce() {
    setTitle("Auftragsverwaltung");
    setSize(700, 500);
    setLocation(500, 200);
    setLayout(null);
    setResizable(false);
    tableScrollPane.setBounds(50, 50, 500, 200);

    addWindowListener(new WindowAdapter() {
        public void windowClosing(WindowEvent e) {
            System.exit(0);
        }
    });
}

public void actionPerformed(ActionEvent e) {

}

@SuppressWarnings("deprecation")
public static void main(String[] args) {
    JFrame f = new sscce();
    f.show();
}
}

每当我尝试运行该程序时，都会得到一个 NullPointerException 和

Whenever I try to running the progam, I get a NullPointerException along with

at javax.swing.table.DefaultTableModel.setDataVector(Unknown Source)
at javax.swing.table.DefaultTableModel.<init>(Unknown Source)
at javax.swing.table.DefaultTableModel.<init>(Unknown Source)
at javax.swing.table.DefaultTableModel.<init>(Unknown Source)

用于以下代码行:

public int getRowCount() {
    return data.length;
}

那是为什么?我的代码有什么问题?程序是否应该能够查找" 数据?

Why is that? What's wrong with my code? Shouldn't the program be able to "find" data?

第二种方法

我试图使用ArrayList作为存储数据的地方...但是下面的注释中标记了"cols-rows-issue" ...找不到数组值(如我现在所述)使用ArrayList).我该怎么解决?

I tried to use an ArrayList as a place for the storage of data... but then there's the 'cols-rows-issue' as marked in the comments below... The array values cannot be found (as I now use an ArrayList). How can I solve that?

import java.awt.Container;
import java.awt.List;
import java.awt.event.ActionEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;

class sscce extends JFrame {

private static final long serialVersionUID = 1L;    // Serial ID...

Container content = getContentPane();

AbstractTableModel myAbstractTableModel = new AbstractTableModel () {
    private static final long serialVersionUID = 1L;    // whatever
    private String[] columnNames = {"AuftragNr", "Datum & Uhrzeit", "Von", "Nach", "erledigt?"};
    private ArrayList<Object> data = new ArrayList<Object>();


    public void addRow(List rowData) {
        data.add(rowData);
        fireTableRowsInserted(data.size() - 1, data.size() - 1);
    }
    public int getColumnCount() {
        return columnNames.length;
    }

    public int getRowCount() {
        return data.length;
        // can be solved via .size();
    }

    public String getColumnName(int col) {
        return columnNames[col];
    }

    public Object getValueAt(int row, int col) {
        return data[row][col];
        // no idea, how to solve that?!
    }

    public Class getColumnClass(int c) {
        return getValueAt(0, c).getClass();
    }

    public boolean isCellEditable(int row, int col) {
        if (col == 4) {
            return true;
        }
        return false;
    }

    public void setValueAt(Object value, int row, int col) {
        data[row][col] = value;
        // same issue here...
        fireTableCellUpdated(row, col);
    }
};

JTable auftragTable = new JTable(myAbstractTableModel);
JScrollPane tableScrollPane = new JScrollPane(auftragTable);
JButton auftragAenderungSpeichern = new JButton("speichern");

public sscce() {
    setTitle("Auftragsverwaltung");
    setSize(700, 500);
    setLocation(500, 200);
    setLayout(null);
    setResizable(false);
    tableScrollPane.setBounds(50, 50, 500, 200);

    addWindowListener(new WindowAdapter() {
        public void windowClosing(WindowEvent e) {
            System.exit(0);
        }
    });
}

@SuppressWarnings("deprecation")
public static void main(String[] args) {
    JFrame f = new sscce();
    f.show();
}
}

---

第三种方法

sscce类:

import java.awt.Container;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;

class sscce extends JFrame {

    private static final long serialVersionUID = 1L;    // Serial ID...

    Container content = getContentPane();

    AbstractTableModel myAbstractTableModel = new AbstractTableModel() {
        private static final long serialVersionUID = 1L;    // whatever
        private String[] columnNames = {"AuftragNr", "Datum & Uhrzeit", "Von", "Nach", "erledigt?"};
        private ArrayList<DataStore> data = new ArrayList<DataStore>();


        public void addRow(DataStore rowData) {
            data.add(rowData);
            fireTableRowsInserted(data.size() - 1, data.size() - 1);
        }
        public int getColumnCount() {
            return columnNames.length;
        }

        public int getRowCount() {
            return data.size(); // length
            // can be solved via .size();
        }

        public String getColumnName(int col) {
            return columnNames[col];
        }

        public Object getValueAt(int row, int col) {
//          change made here
            DataStore rowElement = data.get(row);
            Object value = rowElement.getItemOnPosition(col);
            return value;
        }

        public Class getColumnClass(int c) {
            return getValueAt(0, c).getClass();
        }

        public boolean isCellEditable(int row, int col) {
            if (col == 4) {
                return true;
            }
            return false;
        }

        public void setValueAt(Object value, int row, int col) {
            // change made here
            DataStore rowElement = data.get(row);
            rowElement.setItemOnPosition(col, value);
            fireTableCellUpdated(row, col);
        }
    };

    JTable auftragTable = new JTable(myAbstractTableModel);
    JScrollPane tableScrollPane = new JScrollPane(auftragTable);
    JButton auftragAenderungSpeichern = new JButton("speichern");

    public sscce() {
        setTitle("Auftragsverwaltung");
        setSize(700, 500);
        setLocation(500, 200);
        setLayout(null);
        setResizable(false);
        tableScrollPane.setBounds(50, 50, 500, 200);

        content.add(tableScrollPane);

        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }

    @SuppressWarnings("deprecation")
    public static void main(String[] args) {
        JFrame f = new sscce();
        f.show();
    }
}

DataStore类:

public class DataStore {

    Integer auftragNr;
    String datumUhrzeit;
    String von;
    String nach;
    Boolean status;

    public DataStore(Integer a, String b, String c, String d, Boolean e) {
        auftragNr = a;
        datumUhrzeit = b;
        von = c;
        nach = d;
        status = e;
    }

    public Object getItemOnPosition(int pos) {
        if(pos == 1) {
            return (Integer) auftragNr;
        }
        if(pos == 2) {
            return datumUhrzeit;
        }
        if(pos == 3) {
            return von;
        }
        if(pos == 4) {
            return nach;
        }
        if(pos == 5) {
            return (Boolean) status;
        }
        return null;
    }

    public Object setItemOnPosition(int pos, Object newValue) {
        if(pos == 1) {
            auftragNr = (Integer) newValue;
        }
        if(pos == 2) {
            datumUhrzeit = (String) newValue;
        }
        if(pos == 3) {
            von = (String) newValue;
        }
        if(pos == 4) {
            nach = (String) newValue;
        }
        if(pos == 5) {
            status = (Boolean) newValue;
        }
        return null;
    }
}

推荐答案

我试图使用ArrayList作为数据存储的地方...但是下面的注释中标记了"cols-rows-issue" ...找不到数组值(如我现在所述)使用ArrayList).我该怎么解决?

I tried to use an ArrayList as a place for the storage of data... but then there's the 'cols-rows-issue' as marked in the comments below... The array values cannot be found (as I now use an ArrayList). How can I solve that?

是的，找不到数组值，因为您没有使用数组.您将需要从ArrayList中提取数据.如果您不熟悉ArrayList方法，请查看 ArrayList API .

Yes, the array values can't be found because you're not using an array. You will need to extract the data from the ArrayList. If you are unfamiliar with ArrayList methods, then please check out the ArrayList API.

关于代码，您有编译错误，无论在哪里发现这些类型的错误，都必须调查可能在做什么的错误.主要是您试图将ArrayList当作一个数组来对待，当然不是，因此，使用array.length或使用数组索引(array [i] [j])的数组类型构造将惨遭失败.再次，请查看上面链接的ArrayList API或一个不错的ArrayList教程，以了解如何使用这些工具.例如，如果编译器告诉您ArrayList没有length属性或方法，则在ArrayList API中查找获取所需信息的适当方法.这就是API的目的.

Regarding your code, you have compilation errors, and wherever you find these types of errors, you must look into what you might be doing wrong. Mainly you're trying to treat an ArrayList as if it were an array, which of course it is not, and so array type constructs, using array.length or using array indices (array[i][j]) will fail miserably. Again, please look at the ArrayList API linked to above or a decent ArrayList tutorial to find out how to use these guys. For instance, if the compiler tells you that an ArrayList does not have a length property or method -- then look in the ArrayList API for an appropriate method that gets the information that you want. That's what the API is for.

此外，您的ArrayList不应包含Object，换句话说，它不应为ArrayList<Object>，而应更加具体.通常，表模型的行将包含一个对象，该对象的属性表示该行的每个项目.因此，如果我们调用包含每一行数据RowData的类，则将ArrayList声明为ArrayList<RowData>.因此，要在col的行中获取值，您需要从模型的ArrayList中提取行索引的RowData(假设这是行数据的类的名称)，然后调用对象的getter方法以提取col索引关联的项目.

Also, your ArrayList should not hold Object, in other words it shouldn't be ArrayList<Object> but should be much more specific. Usually a table model's row will hold an object whose properties represent each item of the row. So if we call the class that holds each row's data RowData, your ArrayList would be declared an ArrayList<RowData>. So to get your value at row, col, you'll need to extract the row index's RowData (assuming that this is the name of the row data's class) from your model's ArrayList, and then call the object's getter method to extract the col index-associated item.

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