Java Arraylist有java.lang.IndexOutOfBoundsException? [英] Java Arraylist got java.lang.IndexOutOfBoundsException?
问题描述
我有一个c106a讲义#5的问题。
代码工作,但我仍然有一些错误日志。
线程main中的异常java.lang.IndexOutOfBoundsException:Index:4,Size:4
at java.util.ArrayList。 RangeCheck(ArrayList.java:547)
在java.util.ArrayList.get(ArrayList.java:322)
在UniqueNames.showUnique(UniqueNames.java:23)
在UniqueNames.main (UniqueNames.java:39)
为什么 Arraylist
,它可以自己扩展它的容量,仍然得到一个 OutOfBoundsException
?
这是我的完整代码:
import acm.io. *;
import acm.program.ConsoleProgram;
import acm.util。*;
import java.io. *;
import java.util.ArrayList;
import java.lang。*;
public class UniqueNames extends ConsoleProgram {
static ArrayList< String> meString = new ArrayList< String>();
static String input;
public static void storeUnique(String input){
if(!meString.contains(input))
{
meString.add(input);
}
}
public static void showUnique(ArrayList< String> meString){
System.out.println(Unique name list contains:); (int i = 0; i< = meString.size(); i ++){
System.out.println(meString.get(i));
}
}
public static void main(String [] args){
try {
InputStreamReader stream = new InputStreamReader 。在);
BufferedReader br = new BufferedReader(stream);
while(true){
System.out.println(Enter name:);
String input = br.readLine();
if(input.equals())break;
storeUnique(input);
}
{showUnique(meString);}
}
catch(IOException e){
}
}
}
以下行:
$ b $对于(int i = 0; i <= meString.size(); i ++){System.out.println(meString.get)的
$ b
(一世));
}
应该是:
<对于(int i = 0; i< meString.size(); i ++){
System.out.println(meString.get(i)); pre>
}
这是因为列表的索引从零开始。
索引:4,大小:4
再说一遍。当您调用 get(4)
时,会发生异常,因为您的列表的大小为4. get(4)
将尝试访问列表中的第5个元素。
您可以访问的有效元素为 get(0)
, get(1)
, get(2)
, get(3) code>。
I'm a general 3D artist, switched from my career and started to learn programming. I've got a problem with c106a handout #5.
The code works, but I've still got some error log here.
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 4, Size: 4
at java.util.ArrayList.RangeCheck(ArrayList.java:547)
at java.util.ArrayList.get(ArrayList.java:322)
at UniqueNames.showUnique(UniqueNames.java:23)
at UniqueNames.main(UniqueNames.java:39)
Why does Arraylist
, which can stretch its capacity on its own, still get an OutOfBoundsException
?
Here's my full code:
import acm.io.*;
import acm.program.ConsoleProgram;
import acm.util.*;
import java.io.*;
import java.util.ArrayList;
import java.lang.*;
public class UniqueNames extends ConsoleProgram{
static ArrayList<String> meString = new ArrayList<String>();
static String input ;
public static void storeUnique(String input){
if (!meString.contains(input))
{
meString.add(input);
}
}
public static void showUnique(ArrayList<String> meString){
System.out.println("Unique name list contains:");
for(int i=0 ;i<= meString.size() ;i++){
System.out.println(meString.get(i));
}
}
public static void main(String[] args){
try{
InputStreamReader stream = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(stream);
while (true){
System.out.println("Enter name:");
String input = br.readLine();
if (input.equals("")) break;
storeUnique(input);
}
{showUnique(meString);}
}
catch(IOException e){
}
}
}
The following lines:
for (int i = 0; i <= meString.size(); i++) {
System.out.println(meString.get(i));
}
should be:
for (int i = 0; i < meString.size(); i++) {
System.out.println(meString.get(i));
}
This is because the index of the list starts from zero.
Index: 4, Size: 4
explains a little more. When you call get(4)
, an exception occurs because your list only has a size of 4. get(4)
would attempt to access the 5th element in the list.
Valid elements you can access would be get(0)
, get(1)
, get(2)
, get(3)
.
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