Question

JAVA读取java.txt中内容，并查找该文件中java字符串的个数，并将查找结果保存到“result.txt”中。谢谢了

Answer 1

Use this one, it works fine under JDK 1.5

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;

public class StringCount {

public static void main(String[] args) throws IOException {

File inFile = new File("java.txt");
File outputFile = new File("result.txt");

String fileContextStr = readFile(inFile);

String[] ary = fileContextStr.split("\\s+");

int count = 0;
for(String item: ary){
if(item.equals("java")){
count++;
}
}

System.out.println("Total " + count + " string found in file "+ inFile.getName());

writeToResultFile(outputFile, count);
}

private static void writeToResultFile(File file, int result)
throws IOException {

FileOutputStream fo = new FileOutputStream(file);

fo.write(String.valueOf(result).getBytes());
fo.close();
}

private static String readFile(File file) throws FileNotFoundException,
IOException {

StringBuffer sb = new StringBuffer();

FileReader fl = new FileReader(file);

BufferedReader bf = new BufferedReader(fl);

String context = null;

do {
context = bf.readLine();

if (context == null) {
break;
} else if (!context.trim().equals("")) {
sb.append(context + " ");
}

} while (context != null);

bf.close();

return sb.toString();
}
}

Answer 2

import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

public class StrCount{

public static void main(String[] args) throws IOException {
char[] arr = null;// 存放key
StringBuffer sb = null;
String str;
int value = 0;

FileReader fr = new FileReader("java.txt");// 读取文件的地址.
BufferedReader br = new BufferedReader(fr);
Map<Character, Integer> map = new TreeMap<Character, Integer>();

while (null != (str = br.readLine())) {

arr = str.toCharArray();// 转换成数组然后遍历它放入
for (int i = 0; i < arr.length; i++) {
if (map.get(arr[i]) == null)
map.put(arr[i], 1);
else {
map.put(arr[i], map.get(arr[i]) + 1);
}
}
}
br.close();
Set set = map.keySet();
Character[] keys = new Character[set.size()];
Integer[] Indexs = new Integer[set.size()];
for (Iterator iter = set.iterator(); iter.hasNext();) {
Character key = (Character) iter.next();
Integer index = (Integer) map.get(key);
keys[value] = key;
Indexs[value] = index;
++value;
}
FileOutputStream fos = new FileOutputStream("result.txt");
for (int i = 0; i < keys.length; i++) {
fos.write(keys[i]);

fos.write(Indexs[i]);

}
fos.close();
System.out.println("result.txt 文件已经生成!");
}

}

Answer 3

如果是我，我会用str.splite("java").length-1来计算字符串中"java"的个数。