在此示例中，如何从目标列表中获取所有值

问题描述

我发现了这个示例，其中有两个 s.如何从目标JList获取所有值?我是Java的新手，我想从第二个列表中获取所有值以进行一些测试研究.

I found this example that has two JLists. How can I get all values from the destination JList? I'm new at Java, and I want to get all the values from the second list to do some tests to study.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.SortedSet;
import java.util.TreeSet;

import javax.swing.AbstractListModel;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.ListCellRenderer;
import javax.swing.ListModel;

public class DualListBox extends JPanel {

  private static final Insets EMPTY_INSETS = new Insets(0, 0, 0, 0);

  private static final String ADD_BUTTON_LABEL = "Add >>";

  private static final String REMOVE_BUTTON_LABEL = "<< Remove";

  private static final String DEFAULT_SOURCE_CHOICE_LABEL = "Available Choices";

  private static final String DEFAULT_DEST_CHOICE_LABEL = "Your Choices";

  private JLabel sourceLabel;

  private JList sourceList;

  private SortedListModel sourceListModel;

  private JList destList;

  private SortedListModel destListModel;

  private JLabel destLabel;

  private JButton addButton;

  private JButton removeButton;

  public DualListBox() {
    initScreen();
  }

  public String getSourceChoicesTitle() {
    return sourceLabel.getText();
  }

  public void setSourceChoicesTitle(String newValue) {
    sourceLabel.setText(newValue);
  }

  public String getDestinationChoicesTitle() {
    return destLabel.getText();
  }

  public void setDestinationChoicesTitle(String newValue) {
    destLabel.setText(newValue);
  }

  public void clearSourceListModel() {
    sourceListModel.clear();
  }

  public void clearDestinationListModel() {
    destListModel.clear();
  }

  public void addSourceElements(ListModel newValue) {
    fillListModel(sourceListModel, newValue);
  }

  public void setSourceElements(ListModel newValue) {
    clearSourceListModel();
    addSourceElements(newValue);
  }

  public void addDestinationElements(ListModel newValue) {
    fillListModel(destListModel, newValue);
  }

  private void fillListModel(SortedListModel model, ListModel newValues) {
    int size = newValues.getSize();
    for (int i = 0; i < size; i++) {
      model.add(newValues.getElementAt(i));
    }
  }

  public void addSourceElements(Object newValue[]) {
    fillListModel(sourceListModel, newValue);
  }

  public void setSourceElements(Object newValue[]) {
    clearSourceListModel();
    addSourceElements(newValue);
  }

  public void addDestinationElements(Object newValue[]) {
    fillListModel(destListModel, newValue);
  }

  private void fillListModel(SortedListModel model, Object newValues[]) {
    model.addAll(newValues);
  }

  public Iterator sourceIterator() {
    return sourceListModel.iterator();
  }

  public Iterator destinationIterator() {
    return destListModel.iterator();
  }

  public void setSourceCellRenderer(ListCellRenderer newValue) {
    sourceList.setCellRenderer(newValue);
  }

  public ListCellRenderer getSourceCellRenderer() {
    return sourceList.getCellRenderer();
  }

  public void setDestinationCellRenderer(ListCellRenderer newValue) {
    destList.setCellRenderer(newValue);
  }

  public ListCellRenderer getDestinationCellRenderer() {
    return destList.getCellRenderer();
  }

  public void setVisibleRowCount(int newValue) {
    sourceList.setVisibleRowCount(newValue);
    destList.setVisibleRowCount(newValue);
  }

  public int getVisibleRowCount() {
    return sourceList.getVisibleRowCount();
  }

  public void setSelectionBackground(Color newValue) {
    sourceList.setSelectionBackground(newValue);
    destList.setSelectionBackground(newValue);
  }

  public Color getSelectionBackground() {
    return sourceList.getSelectionBackground();
  }

  public void setSelectionForeground(Color newValue) {
    sourceList.setSelectionForeground(newValue);
    destList.setSelectionForeground(newValue);
  }

  public Color getSelectionForeground() {
    return sourceList.getSelectionForeground();
  }

  private void clearSourceSelected() {
    Object selected[] = sourceList.getSelectedValues();
    for (int i = selected.length - 1; i >= 0; --i) {
      sourceListModel.removeElement(selected[i]);
    }
    sourceList.getSelectionModel().clearSelection();
  }

  private void clearDestinationSelected() {
    Object selected[] = destList.getSelectedValues();
    for (int i = selected.length - 1; i >= 0; --i) {
      destListModel.removeElement(selected[i]);
    }
    destList.getSelectionModel().clearSelection();
  }

  private void initScreen() {
    setBorder(BorderFactory.createEtchedBorder());
    setLayout(new GridBagLayout());
    sourceLabel = new JLabel(DEFAULT_SOURCE_CHOICE_LABEL);
    sourceListModel = new SortedListModel();
    sourceList = new JList(sourceListModel);
    add(sourceLabel, new GridBagConstraints(0, 0, 1, 1, 0, 0,
        GridBagConstraints.CENTER, GridBagConstraints.NONE,
        EMPTY_INSETS, 0, 0));
    add(new JScrollPane(sourceList), new GridBagConstraints(0, 1, 1, 5, .5,
        1, GridBagConstraints.CENTER, GridBagConstraints.BOTH,
        EMPTY_INSETS, 0, 0));

    addButton = new JButton(ADD_BUTTON_LABEL);
    add(addButton, new GridBagConstraints(1, 2, 1, 2, 0, .25,
        GridBagConstraints.CENTER, GridBagConstraints.NONE,
        EMPTY_INSETS, 0, 0));
    addButton.addActionListener(new AddListener());
    removeButton = new JButton(REMOVE_BUTTON_LABEL);
    add(removeButton, new GridBagConstraints(1, 4, 1, 2, 0, .25,
        GridBagConstraints.CENTER, GridBagConstraints.NONE, new Insets(
            0, 5, 0, 5), 0, 0));
    removeButton.addActionListener(new RemoveListener());

    destLabel = new JLabel(DEFAULT_DEST_CHOICE_LABEL);
    destListModel = new SortedListModel();
    destList = new JList(destListModel);
    add(destLabel, new GridBagConstraints(2, 0, 1, 1, 0, 0,
        GridBagConstraints.CENTER, GridBagConstraints.NONE,
        EMPTY_INSETS, 0, 0));
    add(new JScrollPane(destList), new GridBagConstraints(2, 1, 1, 5, .5,
        1.0, GridBagConstraints.CENTER, GridBagConstraints.BOTH,
        EMPTY_INSETS, 0, 0));
  }

  public static void main(String args[]) {
    JFrame f = new JFrame("Dual List Box Tester");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    DualListBox dual = new DualListBox();
    dual.addSourceElements(new String[] { "One", "Two", "Three" });
    dual.addSourceElements(new String[] { "Four", "Five", "Six" });
    dual.addSourceElements(new String[] { "Seven", "Eight", "Nine" });
    dual.addSourceElements(new String[] { "Ten", "Eleven", "Twelve" });
    dual
        .addSourceElements(new String[] { "Thirteen", "Fourteen",
            "Fifteen" });
    dual.addSourceElements(new String[] { "Sixteen", "Seventeen",
        "Eighteen" });
    dual.addSourceElements(new String[] { "Nineteen", "Twenty", "Thirty" });
    f.getContentPane().add(dual, BorderLayout.CENTER);
    f.setSize(400, 300);
    f.setVisible(true);
  }

  private class AddListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      Object selected[] = sourceList.getSelectedValues();
      addDestinationElements(selected);
      clearSourceSelected();
    }
  }

  private class RemoveListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      Object selected[] = destList.getSelectedValues();
      addSourceElements(selected);
      clearDestinationSelected();
    }
  }
}

class SortedListModel extends AbstractListModel {

  SortedSet model;

  public SortedListModel() {
    model = new TreeSet();
  }

  public int getSize() {
    return model.size();
  }

  public Object getElementAt(int index) {
    return model.toArray()[index];
  }

  public void add(Object element) {
    if (model.add(element)) {
      fireContentsChanged(this, 0, getSize());
    }
  }

  public void addAll(Object elements[]) {
    Collection c = Arrays.asList(elements);
    model.addAll(c);
    fireContentsChanged(this, 0, getSize());
  }

  public void clear() {
    model.clear();
    fireContentsChanged(this, 0, getSize());
  }

  public boolean contains(Object element) {
    return model.contains(element);
  }

  public Object firstElement() {
    return model.first();
  }

  public Iterator iterator() {
    return model.iterator();
  }

  public Object lastElement() {
    return model.last();
  }

  public boolean removeElement(Object element) {
    boolean removed = model.remove(element);
    if (removed) {
      fireContentsChanged(this, 0, getSize());
    }
    return removed;
  }
}

推荐答案

您至少可以为SortedListModel添加合适的方法，并根据需要检查其结果.

At a minimum, you can add a suitable method to SortedListModel and examine its result as needed.

public Object[] toArray() {
    return model.toArray(new String[0]);
}
…
System.out.println(Arrays.toString(destListModel.toArray()));

因为引用的示例早于 Java 1.5 ，更好的解决方案是指定

Because the example cited predates generics, introduced in Java 1.5, a better solution is to specify a generic type parameter for the SortedListModel.

private SortedListModel<String> destListModel = new SortedListModel<>();
…
class SortedListModel<E> extends AbstractListModel<E> {

    private final SortedSet<E> model;

    public SortedListModel() {
        model = new TreeSet<>();
    }

    public List<E> toList() {
        return new ArrayList<>(model);
    }

    @Override
    public E getElementAt(int index) {
        return (E) model.toArray()[index];
    }

    public void add(E element) {
        if (model.add(element)) {
            fireContentsChanged(this, 0, getSize());
        }
    }
    …
}
…
System.out.println(destListModel.toList());

这篇关于在此示例中，如何从目标列表中获取所有值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！