i have file txt in desktop :
1 5 23
2 5 25
3 30 36
i want sum column by column 1 + 2 + 3 =... and 5 + 5...n and 23,...n
Scanner sc = new Scanner (file("patch");
while (sc.hasNextLine)
{
//每个列的总和
}
帮帮我,谢谢
我会try-with-resources
用来清理我Scanner
的File
。另外,您可以Scanner
在line
输入的周围构造一个来获取您的int
列(这不需要关闭,因为String
无论如何都无法关闭它们)。就像是,
try (Scanner sc = new Scanner(new File("patch"))) {
while (sc.hasNextLine()) {
String line = sc.nextLine();
Scanner row = new Scanner(line);
long sum = 0;
int count = 0;
while (row.hasNextInt()) {
int val = row.nextInt();
if (count == 0) {
System.out.print(val);
} else {
System.out.printf(" + %d", val);
}
sum += val;
count++;
}
System.out.println(" = " + sum);
}
} catch (IOException e) {
e.printStackTrace();
}
作为Scanner(String)
构造器Javadoc文档
构造一个新的
Scanner
,生成从指定的字符串扫描的值。
编辑总结列是有点麻烦,但你可以阅读一切成多维List<List<Integer>>
像
try (Scanner sc = new Scanner(new File("patch"))) {
List<List<Integer>> rows = new ArrayList<>();
int colCount = 0;
while (sc.hasNextLine()) {
List<Integer> al = new ArrayList<>();
String line = sc.nextLine();
Scanner row = new Scanner(line);
colCount = 0;
while (row.hasNextInt()) {
colCount++;
int val = row.nextInt();
al.add(val);
}
rows.add(al);
}
for (int i = 0; i < colCount; i++) {
long sum = 0;
for (List<Integer> row : rows) {
sum += row.get(i);
}
if (i != 0) {
System.out.print("\t");
}
System.out.print(sum);
}
System.out.println();
} catch (IOException e) {
e.printStackTrace();
}
编辑2为了提高效率,您可能更喜欢使用Map
like
try (Scanner sc = new Scanner(new File("patch"))) {
Map<Integer, Integer> cols = new HashMap<>();
while (sc.hasNextLine()) {
String line = sc.nextLine();
Scanner row = new Scanner(line);
int colCount = 0;
while (row.hasNextInt()) {
int val = row.nextInt();
if (cols.containsKey(colCount)) {
val += cols.get(colCount);
}
cols.put(colCount, val);
colCount++;
}
}
for (int i : cols.values()) {
System.out.printf("%d\t", i);
}
System.out.println();
} catch (IOException e) {
e.printStackTrace();
}
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我来说两句