Question

这是我遇到的错误。如果您需要有关完整代码的更多信息，请告诉我。

Exception in thread "AWT-EventQueue-0" java.lang.IndexOutOfBoundsException: Index: 2, Size: 2
    at java.util.ArrayList.rangeCheck(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at main.Field.upCountFirst(Field.java:158)
    at main.Field$1.actionPerformed(Field.java:55)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$500(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

这是我的代码，我不明白它有什么问题，我不应该超出范围……（（不太擅长编程，所以我不太清楚这个问题。）

list.add(x);
String temp = x;
for(int i = 0; i<list.size(); i++) {
    System.out.println(list.get(i) + " X" + list.size());
    if(list.size() >= 2) {
        temp = temp + list.get(i+1);
    }
}
System.out.println(temp);

Answer 1

您会在错误的第一行看到：索引：2，大小：2

if(list.size() >= 2) {
    temp = temp + list.get(i+1);
}

所以这里满足条件，因为列表大小为2。

temp = temp + list.get(i+1);->这是问题所在。

您是说：get（i + 1）等于2，但索引实际上是1。第一次迭代= i+1 => 0+1 = 1 第二次迭代= i+1 => 1+1 = 2 --->这是您超越界限的地方。

Answer 2

在Java数组和列表中，索引起始于索引0，结束于索引size - 1。因此，如果您的循环中是i = 1，那么list.get(i + 1)将导致IndexOutOfBoundsException，因为您正在尝试访问不存在的索引2。

Java索引超出范围例外索引：2，大小：2

2 个答案: