我对这些数据结构感到困惑，我只想构建一种2D类型的结构以使用数据。
这是txt文件：
COSTS A B C D E F G H I J SUPPLY
Source1 6 7 10 16 5 8 15 15 6 8 175
Source2 10 14 8 17 13 9 18 20 9 7 200
Source3 9 4 8 12 10 10 8 5 9 10 225
Source4 12 8 9 10 6 15 4 9 7 0 300
Source5 6 9 17 7 6 13 6 7 6 0 250
Source6 9 10 9 13 9 8 9 3 4 9 100
Source7 16 18 7 14 5 6 10 5 4 5 150
Source8 7 5 8 3 8 5 10 8 8 14 300
Source9 8 10 9 6 4 9 17 7 5 8 100
Source10 5 8 4 5 7 14 6 3 13 9 200
DEMAND 150 250 110 275 175 350 300 180 90 120
这是我现在的代码：
public static void main(String[] args) {
Object[][] table = new Object[13][];
Scanner sc = new Scanner(System.in);
//sc.useDelimiter("\\Z");
while(sc.hasNextLine()) {
String sc1 = sc.nextLine();
ArrayList<String> arrayList =
new ArrayList<String>(Arrays.asList(sc1.split(" ")));
System.out.println(arrayList);
}
sc.close();
}
答案 0 :(得分：0)
I am guessing you want to load the data into table = new Object[13][]; if so this is the code you need to use;
public static void main(String[] args) {
Object[][] table = new Object[13][];
Scanner sc = new Scanner(System.in);
int i = 0;
while (sc.hasNextLine()) {
String sc1 = sc.nextLine();
table[i] = sc1.split(" ");
i++;
}
sc.close();
System.out.println(Arrays.deepToString(table));
}
Basically I am just setting each index of the table to a String array that contains strings split by space.
答案 1 :(得分：0)
显然可以使用数组来完成这种事情，但是除非知道要读取的特定数据文件，否则无法轻松知道要读取的文件中包含多少数据行。始终包含相同数量的数据线。许多程序员将使用ArrayList或List接口对象来保存数据，如果仍然需要类型数组，则将集合转换为该类型数组。
填充2D阵列：
首先，您需要知道数据文件中实际包含多少个有效文件数据行。最简单的方法是进行两次通过读取。第一遍计算文件中有多少有效数据行，以便可以适当地确定数组大小，然后第二遍填充2D数组。确定文件可能包含的行数的方法很简单，但是没有确定文件是否为有效数据行（实际上包含数据的行）的简便方法。
您的特定数据文件似乎包含三个特定部分：
将每个部分检索到单独的数组中可能是有益的，因此我在下面提供的代码演示了如何实现此目的。首先，您需要建立3个类成员变量，它们将在整个类中具有全局作用域：
String[] headerData; // First data Line in file is the Header Information
Object[][] data; // The 2D Object Array to hold raw File Data
int[] demandData; // Last data line in file is the Demand Information
现在将以下方法复制/粘贴到您的班级中：
private void readDataFile(String filePath) {
Scanner sc;
int maxColumns = 0;
int validLines = 0;
int endLine;
try {
sc = new Scanner(new File(filePath));
String dataLine = "";
// First Pass:
while (sc.hasNextLine()) {
String fileLine = sc.nextLine().trim();
/* Skip Blank Lines or lines that start with
a comment character (if any)... */
if (fileLine.equals("") || fileLine.startsWith(";") || fileLine.startsWith("#")) {
continue;
}
validLines++; //This line must be a valid data line, so increment counter.
dataLine = fileLine;
if (validLines == 1) {
// Get Header Information.
headerData = dataLine.split("\\s+"); // Grab the Columns Header Names
maxColumns = headerData.length; // Get the number of data columns
}
}
endLine = validLines;
demandData = new int[endLine - 2]; // Initialize the demandData array
data = new Object[endLine - 2][maxColumns]; // Initialize the data array
// Make sure the last line actually contains data
if (dataLine.equals("")) {
// No it doesn't so there is no DEMAND line.
System.out.println("No DEMAND Data Available In File!");
sc.close();
return;
}
/* Fill the demandData int array with Integer data...
The dataLine variable at this point will hold
the last valid file data line which happend to
be the Demand Line */
String[] dl = dataLine.split("\\s+"); // split the data line on 1 or more whitespaces.
// Don't want the word "DEMAND" so we start from 1.
for (int i = 1; i < dl.length; i++) {
demandData[i-1] = Integer.parseInt(dl[i]);
}
// Second Pass (fill the data aray):
sc = new Scanner(new File("MyDataFile.txt"));
validLines = 0;
while (sc.hasNextLine()) {
String fileLine = sc.nextLine().trim();
/* Skip Blank Lines or lines that start with
a comment character (if any)... */
if (fileLine.equals("") || fileLine.startsWith(";") || fileLine.startsWith("#")) {
continue;
}
validLines++; //This line must be a valid data line, so increment counter.
if (validLines == endLine) {
break;
}
if (validLines == 1) { continue; } // Skip the header line
dl = fileLine.split("\\s+"); // split the data line on 1 or more whitespaces.
for (int i = 0; i < dl.length; i++) {
if (i == 0) {
data[validLines-2][i] = dl[i]; //String Object - Sources Name
}
else {
data[validLines-2][i] = Integer.parseInt(dl[i]); // Integer Object
}
}
}
sc.close(); /* Close the reader.
Make sure the number of data rows equals the number
of Demand values otherwise inform of mismatch. */
if (data.length != demandData.length) {
System.out.println("Warning: There is missing DEMAND information (data mismatch)!\n"
+ "There is no available Demand data for one of the Sources.");
}
}
catch (FileNotFoundException ex) {
System.err.println(ex.getMessage());
}
}
这是您可能使用此方法的方式：
readDataFile("10by10.txt");
if (data != null) {
// Header Information:
System.out.println("Header Column Names:\n" +
Arrays.toString(headerData) + "\n");
// The Actual Data:
System.out.println("File Data:");
for (int i = 0; i < data.length; i++) {
System.out.println(Arrays.toString(data[i]));
}
// The Demand Information:
System.out.println("\nDemand Values For Each Row:\n" +
Arrays.toString(demandData) + "\n");
}
如果您提供示例文件数据，则将在控制台窗口中显示以下内容：
Header Column Names:
[COSTS, A, B, C, D, E, F, G, H, I, J, SUPPLY]
File Data:
[Source1, 6, 7, 10, 16, 5, 8, 15, 15, 6, 8, 175]
[Source2, 10, 14, 8, 17, 13, 9, 18, 20, 9, 7, 200]
[Source3, 9, 4, 8, 12, 10, 10, 8, 5, 9, 10, 225]
[Source4, 12, 8, 9, 10, 6, 15, 4, 9, 7, 0, 300]
[Source5, 6, 9, 17, 7, 6, 13, 6, 7, 6, 0, 250]
[Source6, 9, 10, 9, 13, 9, 8, 9, 3, 4, 9, 100]
[Source7, 16, 18, 7, 14, 5, 6, 10, 5, 4, 5, 150]
[Source8, 7, 5, 8, 3, 8, 5, 10, 8, 8, 14, 300]
[Source9, 8, 10, 9, 6, 4, 9, 17, 7, 5, 8, 100]
[Source10, 5, 8, 4, 5, 7, 14, 6, 3, 13, 9, 200]
Demand Values For Each Data Row:
[150, 250, 110, 275, 175, 350, 300, 180, 90, 120]
填充2D列表界面：
在这里，我们的操作有所不同，您会发现它可以轻松得多。这次，我们的 readDataFile（）方法返回了String类型的2D List Interface对象，我们可以轻松地操作该对象以获取Header Coloumn Names，Raw Data和Demand Data值。
这是方法：
private List<List<String>> readDataFile(String filePath) {
Scanner sc;
List<List<String>> list = new ArrayList<>();
try {
sc = new Scanner(new File(filePath));
while (sc.hasNextLine()) {
String fileLine = sc.nextLine().trim();
/* Skip Blank Lines or lines that start with
a comment character (if any)... */
if (fileLine.equals("") || fileLine.startsWith(";") || fileLine.startsWith("#")) {
continue;
}
/* Valid data line we want...add it to the list.
Here we split the data line into a String array
then we use the Arrays.asList() method to convert
it to a List then we add that List to our 2D List.
All done in one line of code. */
list.add(Arrays.asList(fileLine.split("\\s+")));
}
sc.close(); // Close the reader.
}
catch (FileNotFoundException ex) {
System.err.println(ex.getMessage());
}
return list;
}
并针对示例数据文件使用此方法：
// Read the file data and place it all into a 2D List
List<List<String>> list = readDataFile("10by10.txt");
// Get the Header Column Names from first ArrayList
String[] headerData = list.get(0).toArray(new String[0]);
// The 2D Object Array to hold raw File Data
Object[][] data = new Object[list.size() - 2][headerData.length];
for(int i = 1; i < list.size() - 1; i++) {
for (int j = 0; j < list.get(i).size(); j++) {
if (j == 0) {
data[i - 1][j] = list.get(i).get(j);
}
else {
data[i - 1][j] = Integer.parseInt(list.get(i).get(j));
}
}
}
// Last data line in file is the DEMAND Values
String[] tmp = list.get(list.size() - 1).toArray(new String[0]);
int[] demandData = new int[tmp.length - 1];
for (int i = 1; i < tmp.length; i++) {
demandData[i - 1] = Integer.parseInt(tmp[i]);
}
if (data != null) {
// Header Information:
System.out.println("Header Column Names:\n"
+ Arrays.toString(headerData) + "\n");
// The Actual Data:
System.out.println("File Data:");
for (int i = 0; i < data.length; i++) {
System.out.println(Arrays.toString(data[i]));
}
// The Demand Information:
System.out.println("\nDemand Values For Each Row:\n"
+ Arrays.toString(demandData) + "\n");
}
控制台窗口的输出将与上面显示的相同。