Java 将最后一个元素的信息添加到ArrayList的末尾
我的问题很简单。我试图将arrayList的最后一个元素添加到该数组列表的末尾,其行如下:Java 将最后一个元素的信息添加到ArrayList的末尾,java,arraylist,indexoutofboundsexception,Java,Arraylist,Indexoutofboundsexception,我的问题很简单。我试图将arrayList的最后一个元素添加到该数组列表的末尾,其行如下: ArrayList.add(ArrayList.get(ArrayList.size())); 但我得到的是一种非同寻常的感觉 那么,有没有一种方法可以做到这一点而不出现异常呢?快速回答。该行不包含在任何循环中。arrayList具有大小。我已经用ArrayList.size()-1尝试过了,但是没有用。下面是它包含的完整代码块 public class SaveButtonListener im
ArrayList.add(ArrayList.get(ArrayList.size()));
但我得到的是一种非同寻常的感觉
那么,有没有一种方法可以做到这一点而不出现异常呢?快速回答。该行不包含在任何循环中。arrayList具有大小。我已经用ArrayList.size()-1尝试过了,但是没有用。下面是它包含的完整代码块
public class SaveButtonListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
JFileChooser fileChooser = new JFileChooser(".");
int status = fileChooser.showSaveDialog(null);
if (status == JFileChooser.APPROVE_OPTION) {
File selectedFile = fileChooser.getSelectedFile();
String fileName = selectedFile.getPath();
File imageFolder = new File(fileName);
imageFolder.mkdir();
//tokenizes the path into an arraylist
String delims = "/";
ArrayList<String> fileTokensList = new ArrayList<>();
String[] fileTokens = fileName.split(delims);
fileTokensList.addAll(Arrays.asList(fileTokens));
//adds the name of the current image
fileTokensList.add(fileTokensList.get(fileTokensList.size()));
//rebuilds all the tokens into one string path
StringBuilder builder = new StringBuilder();
for (int s = 0; s < fileTokensList.size(); s++) {
if (s == 0) {
builder.append(fileTokensList.get(s));
} else {
builder.append("/");
builder.append(fileTokensList.get(s));
}
}
String textFileName = builder.toString();
System.out.println(textFileName);
try {
File saveFile = new File(textFileName);
FileWriter fileWriter = new FileWriter(saveFile);
try (BufferedWriter bufferedWriter = new BufferedWriter(fileWriter)) {
for (int i = 0; i < Driver.vehicleList.size()+1; i++) {
//writes the text file (one entry per line
bufferedWriter.write(Driver.vehicleList.get(i).getPrice());
bufferedWriter.write("\t");
bufferedWriter.write(Driver.vehicleList.get(i).getYear());
bufferedWriter.write("\t");
bufferedWriter.write(Driver.vehicleList.get(i).getMake());
bufferedWriter.write("\t");
bufferedWriter.write(Driver.vehicleList.get(i).getModel());
bufferedWriter.write("\t");
bufferedWriter.write(Driver.vehicleList.get(i).getComments());
bufferedWriter.newLine();
//adds the name of the current image
fileTokensList.add(Integer.toString(i));
//rebuilds all the tokens into one string path
StringBuilder imagePathBuilder = new StringBuilder();
for (int s = 0; s < fileTokensList.size(); s++) {
if (s == 0) {
imagePathBuilder.append(fileTokensList.get(s));
} else {
imagePathBuilder.append("/");
imagePathBuilder.append(fileTokensList.get(s));
}
}
String imageFileName = builder.toString();
//resaves the picture to the same place
Path FROM = Paths.get(Driver.vehicleList.get(i).getCarPicture());
Path TO = Paths.get(imageFileName);
//overwrite existing file, if exists
CopyOption[] options = new CopyOption[]{
StandardCopyOption.REPLACE_EXISTING,
StandardCopyOption.COPY_ATTRIBUTES
};
Files.copy(FROM, TO, options);
}
}
} catch (IOException IO) {
System.out.println("Error writing to file");
}
JOptionPane.showMessageDialog(null, "All your information has been saved");
}
}
}
公共类SaveButtonListener实现ActionListener{
@凌驾
已执行的公共无效操作(操作事件e){
JFileChooser fileChooser=新的JFileChooser(“.”);
int status=fileChooser.showsavedilog(null);
if(status==JFileChooser.APPROVE\u选项){
File selectedFile=fileChooser.getSelectedFile();
字符串文件名=selectedFile.getPath();
File imageFolder=新文件(文件名);
mkdir();
//将路径标记为arraylist
字符串delims=“/”;
ArrayList fileTokensList=新的ArrayList();
String[]fileTokens=fileName.split(delims);
fileTokensList.addAll(Arrays.asList(fileTokens));
//添加当前图像的名称
添加(fileTokensList.get(fileTokensList.size());
//将所有令牌重建为一个字符串路径
StringBuilder=新的StringBuilder();
对于(int s=0;s
这段代码是用来将文件保存到某个位置的,我对令牌进行了大量的处理并重建了该路径。我是要走很长的路才能找到一个简单的解决方案,还是做得对?ArrayList.get(int index)
如果index
值介于0和Array.size()之间,则可以使用-1
。由于您发送的是Array.size()
,因此您将前往数组的无效位置,从而获得异常
如何解决这个问题?好吧,你应该把你想添加的内容发布出来,你会得到答案的
ArrayList<String> fileTokensList = new ArrayList<>();
一种方法是使用“+”串联运算符,编译器将自动为您创建字符串。尝试更改:
ArrayList.add(ArrayList.get(ArrayList.size()));
到
我做了,它继续,但没有出现在屏幕上end@BlaineShelton我认为一点调试可能会对您有所帮助,首先检查
fileTokensList.get(fileTokensList.size()-1)返回的内容
然后,如果成功地实现了您想要的功能,请执行下一步,将其存储在某个变量中,然后添加。我正在尝试将最后一个元素中的信息添加到数组的末尾,而不是数组的大小(标题上我的错误)
ArrayList.add(ArrayList.get(ArrayList.size()));
ArrayList.add(ArrayList.get(ArrayList.size()-1));