大家好，我是Java新手，我正在尝试将一个ArrayList克隆到驻留在另一个类中的另一个ArrayList中，下面是我的www.example.com中的原始ArrayList的代码TaskPage.java:

public ArrayList<String> tName = new ArrayList<>();
    public ArrayList<String> tDesc = new ArrayList<>();
    public ArrayList<String> fLName = new ArrayList<>();
    public ArrayList<String> tStatus = new ArrayList<>();
    public ArrayList<Integer> tDuration = new ArrayList<>();
    public ArrayList<String> tID = new ArrayList<>();    

String TName = taskName.getText();
        tName.add(TName);
        String TDescription = taskDescription.getText();
        tDesc.add(TDescription);
        String FName = FirstName.getText();
        String LName = LastName.getText();
        fLName.add(FName + " " + LName);
        int Duration = Integer.parseInt(taskDuration.getText());
        tDuration.add(Duration);
        String taskID;

        String taskNumber = "";
        Random rand = new Random();

        int rNum = rand.nextInt(21);

        taskNumber = "0" + Integer.toString(rNum);

        TaskClass tClass = new TaskClass();
        taskID = tClass.createTaskID(TName, taskNumber, FName);
        tID.add(taskID);

下面是www.example.com的代码Report.java:

public class Report {
    TaskPage tPage = new TaskPage();
    public ArrayList<String> taskName;
    public ArrayList<String>  taskDesc;
    public ArrayList<String>  fLName;
    public ArrayList<String>  taskStatus;
    public ArrayList<String>  taskDuration;
    public ArrayList<String>  taskID;

    public String res = "";

    public void init() {
        taskName = (ArrayList)tPage.tName.clone();
    taskDesc = (ArrayList)tPage.tDesc.clone();
     fLName = (ArrayList)tPage.fLName.clone();
     taskStatus = (ArrayList)tPage.tStatus.clone();
     taskDuration = (ArrayList)tPage.tDuration.clone();
        taskID = (ArrayList)tPage.tID.clone();
    }

    public void statusDone() {
        init();
        for (int k=0; k <= tPage.tName.size(); k++) {
            if (tPage.tStatus.get(k) == "Done") {
                res = tPage.fLName.get(k) + ", " + tPage.tName.get(k) + ", " + tPage.tDuration.get(k) + "\n";
            } else {
                res = "There is nothing to display here!";
            }
        }
    }
}

最后是我的www.example.com的代码ComingSoon.java:

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        Report rpt = new Report();
        rpt.statusDone();
        String Status = rpt.res;
        JOptionPane.showMessageDialog(null, Status);
    }

当我运行代码时，它给出了错误：

Exception in thread "AWT-EventQueue-0" java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0
    at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
    at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
    at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
    at java.base/java.util.Objects.checkIndex(Objects.java:359)
    at java.base/java.util.ArrayList.get(ArrayList.java:427)
    at userlogin.Report.statusDone(Report.java:36)
    at userlogin.ComingSoon.jButton1ActionPerformed(ComingSoon.java:188)
    at userlogin.ComingSoon$1.actionPerformed(ComingSoon.java:54)
    at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1972)
    at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2313)
    at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
    at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
    at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:279)
    at java.desktop/java.awt.Component.processMouseEvent(Component.java:6626)
    at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3389)
    at java.desktop/java.awt.Component.processEvent(Component.java:6391)
    at java.desktop/java.awt.Container.processEvent(Container.java:2266)
    at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5001)
    at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324)
    at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
    at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4948)
    at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4575)
    at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4516)
    at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2310)
    at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2780)
    at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
    at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773)
    at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722)
    at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:716)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:97)
    at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:746)
    at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:744)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:743)
    at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
    at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
    at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
    at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
    at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

1条答案

按热度按时间

zbdgwd5y1#

您的代码中存在许多问题，但您得到ArrayIndexOutOfBoundsException的原因是statusDone()函数中的for循环错误。

for (int k=0; k <= tPage.tName.size(); k++) {
    ...

k = tPage.tName.size()时出现问题。
由于数组（和ArrayLists）是0索引的，k-1处的元素是最后一个元素，因此tPage.tStatus.get(k)引发ArrayIndexOutOfBoundsException。您应该使用<而不是<=。
另一个可能的问题是，你似乎没有在任何地方调用init()，我假设init()应该在statusDone()之前调用。
有关提高可读性和可维护性的其他建议：

创建一个包含6个字段的Task类，并将6个列表替换为ArrayList<Task>（感谢Dave Newton），而不是包含6个字符串的ArrayList
使用new ArrayList<>(tPage.tName)而不是(ArrayList)tPage.tName.clone()。通常不鼓励在集合上使用clone()，并且强制转换它也不是很干净。
考虑将init()中的所有内容都移到构造函数中。当您调用new Report()时，代码就开始运行

赞(0）回复(0）举报 2022-11-10

netbeans 正在尝试从另一个类访问ArrayList

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