private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8
时间: 2024-04-25 19:23:53 浏览: 143
引用[1]中的代码段给出了一个私有静态常量MAX_ARRAY_SIZE的定义,它的值是Integer.MAX_VALUE - 8。这个常量在代码中被用来限制数组的最大容量。引用[1]中的代码还展示了一个grow()方法,它用于动态扩容数组。在这个方法中,通过计算新容量newCapacity来确定是否需要扩容,并使用Arrays.copyOf()方法来创建一个新的数组。如果新容量超过了MAX_ARRAY_SIZE的限制,就会调用hugeCapacity()方法来确定最终的容量大小。引用[2]中的测试代码展示了Arrays.copyOf()方法的使用,它可以将一个数组复制到一个新的数组中,并指定新数组的长度。引用[3]中的测试代码展示了ArrayList类的ensureCapacity()方法的使用,它可以确保ArrayList的容量至少达到指定的值。
相关问题
10个8g的二进制文件,其中每8个字节为一个64bits整数,对这10个文件进行快速排序处理,找出10个文件中重复的数据,使用java语言实现上述操作,要求输出重复数据的整数值,该值所在的文件,以及所在文件的位置,并将输出结果存储到Task3.out文件中
好的,以下是使用Java语言实现上述操作的一种可能的解决方案:
```java
import java.io.*;
import java.nio.ByteBuffer;
import java.nio.LongBuffer;
import java.nio.channels.FileChannel;
import java.util.Arrays;
public class SortAndFindDuplicates {
private static final int LONG_SIZE = 8; // 8 bytes per long
private static final int BUFFER_SIZE = 1024 * 1024; // 1MB buffer
private static void sortFile(String filename) throws IOException {
RandomAccessFile file = new RandomAccessFile(filename, "rw");
FileChannel channel = file.getChannel();
ByteBuffer buffer = ByteBuffer.allocate(BUFFER_SIZE);
LongBuffer longBuffer = buffer.asLongBuffer();
long[] array = new long[BUFFER_SIZE / LONG_SIZE];
int bytesRead;
do {
buffer.clear();
bytesRead = channel.read(buffer);
if (bytesRead > 0) {
longBuffer.flip();
longBuffer.get(array, 0, bytesRead / LONG_SIZE);
Arrays.sort(array, 0, bytesRead / LONG_SIZE);
longBuffer.clear();
longBuffer.put(array, 0, bytesRead / LONG_SIZE);
channel.position(channel.position() - bytesRead);
buffer.limit(bytesRead);
channel.write(buffer);
}
} while (bytesRead > 0);
channel.close();
file.close();
}
private static void findDuplicates(String[] filenames, String outputFilename) throws IOException {
int numFiles = filenames.length;
RandomAccessFile[] files = new RandomAccessFile[numFiles];
FileChannel[] channels = new FileChannel[numFiles];
ByteBuffer[] buffers = new ByteBuffer[numFiles];
LongBuffer[] longBuffers = new LongBuffer[numFiles];
long[][] arrays = new long[numFiles][BUFFER_SIZE / LONG_SIZE];
int[] positions = new int[numFiles];
for (int i = 0; i < numFiles; i++) {
files[i] = new RandomAccessFile(filenames[i], "r");
channels[i] = files[i].getChannel();
buffers[i] = ByteBuffer.allocate(BUFFER_SIZE);
longBuffers[i] = buffers[i].asLongBuffer();
positions[i] = -1;
}
int bytesRead;
boolean finished = false;
while (!finished) {
for (int i = 0; i < numFiles; i++) {
if (positions[i] == -1) {
bytesRead = channels[i].read(buffers[i]);
if (bytesRead == -1) {
finished = true;
break;
}
buffers[i].flip();
longBuffers[i].limit(bytesRead / LONG_SIZE);
longBuffers[i].get(arrays[i], 0, bytesRead / LONG_SIZE);
buffers[i].clear();
positions[i] = 0;
}
}
if (!finished) {
long minValue = Long.MAX_VALUE;
int minIndex = -1;
for (int i = 0; i < numFiles; i++) {
if (positions[i] != -1 && arrays[i][positions[i]] < minValue) {
minValue = arrays[i][positions[i]];
minIndex = i;
}
}
int count = 0;
for (int i = 0; i < numFiles; i++) {
if (positions[i] != -1 && arrays[i][positions[i]] == minValue) {
count++;
}
}
if (count > 1) {
try (BufferedWriter writer = new BufferedWriter(new FileWriter(outputFilename, true))) {
writer.write(String.format("%d found in %s, positions: ", minValue, filenames[minIndex]));
for (int i = 0; i < numFiles; i++) {
if (positions[i] != -1 && arrays[i][positions[i]] == minValue) {
writer.write(String.format("%d ", positions[i]));
}
}
writer.newLine();
}
}
for (int i = 0; i < numFiles; i++) {
if (positions[i] != -1 && arrays[i][positions[i]] == minValue) {
positions[i]++;
if (positions[i] == BUFFER_SIZE / LONG_SIZE || positions[i] == longBuffers[i].limit()) {
positions[i] = -1;
}
}
}
}
}
for (int i = 0; i < numFiles; i++) {
channels[i].close();
files[i].close();
}
}
public static void main(String[] args) throws IOException {
String[] filenames = {"file1.bin", "file2.bin", "file3.bin", "file4.bin", "file5.bin",
"file6.bin", "file7.bin", "file8.bin", "file9.bin", "file10.bin"};
for (String filename : filenames) {
sortFile(filename);
}
findDuplicates(filenames, "Task3.out");
}
}
```
该程序将首先对每个文件进行快速排序,然后使用归并排序的思想在所有文件中查找重复项。对于每个重复项,程序将其整数值、文件名和位置写入Task3.out文件中。
请注意,该程序假定每个文件的大小不超过2GB,因为Java中的数组大小限制为Integer.MAX_VALUE。如果您的文件更大,请考虑使用外部排序或其他技术来处理文件。
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