将arraylist变成数组

Question

这是我目前所拥有的

try{
          // Open the file that is the first 
          // command line parameter
          FileInputStream fstream = new FileInputStream("Patient.txt");
          // Get the object of DataInputStream
          DataInputStream in = new DataInputStream(fstream);
          BufferedReader br = new BufferedReader(new InputStreamReader(in));
          String strLine;
          //Read File Line By Line
          List<String> lines = new ArrayList<String>();
          while ((strLine = br.readLine()) != null) {

          }
          //Close the input stream
          in.close();
            }catch (Exception e){//Catch exception if any
          System.err.println("Error: " + e.getMessage());
          }
    ArrayList<Patient1> patients=new ArrayList<Patient1>();
    Patient1 p = new Patient1();
    //set value to the patient object
    patients.add(p);
    System.out.println(p);
    // File i/o

这是我的txt文件

001, "John", 17, 100, 65, 110, 110, 110, 109, 111, 114, 113, "Swaying, Nausea"
002, "Sun Min", 18, 101, 70, 113, 113, 110, 119, 111, 114, 113, "None"
003, "Ray Allen", 25, 103, 74, 110, 110, 110, 109, 111, 108, 109, "Difficulty driving"
004, "Michael Jordan", 26, 104, 84, 114, 115, 118, 117, 119, 120, 123, "Loss of        bladder control"
005, "Kobe Bryant", 28, 110, 80, 118, 119, 120, 119, 120, 120, 120, "None"

我有我所有的方法和资源，我需要做的就是把数组列表变成一个数组，这样我就可以做类似的事情

    Patient1 average[] = {p[0], p[1], p[2], p[3], p[4]};
    int totalage = 0;
    double totalweight = 0;
    for (int i=0; i<average.length; i++) {
    totalage = (average[i].getAge() + totalage);
    totalweight = (average[i].getWeight() + totalweight);

Answer 1

toArray 是你想要的。

例如

ArrayList<String> l = something();
String[] foo = l.toArray(new String[foo.size()]);

ArrayList toArray

编辑

在多看你的例子之后。您无需将其转换为数组，只需在循环中调用 arraylist 上的 get 函数并进行计算。您可能想花一点时间查看 javadoc。

Answer 2

如果您想逐行读取文件，则可以使用 FileUtils 类 common-io。

使用FileUtils.readLines()我们可以逐行读取文件内容并将结果作为字符串列表返回

例子：

File file = new File("sample.txt"); 

try { 
List<String> contents = FileUtils.readLines(file); 
for (String line : contents) { 
System.out.println(line);             
} 
} catch (IOException e) { 
e.printStackTrace();     
} 

Answer 3

这样使用

ArrayList<Patient1> patients = new ArrayList<Patient1>();
Patient1 p = new Patient1();
patients.add(p);
String[] pArray = new String[patients.size()];
pArray = patients.toArray(pArray);
for(String s : pArray)
System.out.println(s);

希望对你有所帮助..