[置顶] Java编程笔试题之一 ----文件操作

package com.sgl.io;

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;

public class FileFindString {
public static void findStringInFile(String fileName, String subStr)
throws Exception {
BufferedReader br = new BufferedReader(new FileReader(fileName));
Map<Integer, String> res = new HashMap<>();
int lineNum = 0; //记录行号
String line;
while ((line = br.readLine()) != null) {
lineNum++;
//	第一种：contains
//	if (line.contains(subStr)) {
//		res.put(lineNum, line);
//``}
//	第二种：indexOf
if(line.indexOf(subStr)!=-1){
res.put(lineNum, line);
}
}
//遍历hashMap，key为行号，value为字符串
if (res.isEmpty()) {
System.out.println("文件【" + fileName + "】中没有【" + subStr + "】子串");
} else {
Iterator<Entry<Integer, String>> it = res.entrySet().iterator();
while (it.hasNext()) {
Entry<Integer, String> entry = it.next();
System.out.println("第" + entry.getKey() + "行:\t"
+ entry.getValue());
}
}
br.close();
}

public static void main(String[] args) throws Exception {
findStringInFile("test1.txt", "time");
}

}