blocks|key|1294683|text|还有Scanner。您可以像使用BufferedReader一样使用它|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1294684|Scanner+scanner+=+new+Scanner(myString);
while+(scanner.hasNextLine())+{
++String+line+=+scanner.nextLine();
++//+process+the+line
}
scanner.close();|code-block|syntax|javascript|1294685|我认为这种方法比两种建议的方法都要干净一些。|1294686|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/javase/6/docs/api/java/util/Scanner.html^0|2|7|G|E|2|7|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

There is also <a href="http://java.sun.com/javase/6/docs/api/java/util/Scanner.html" rel="noreferrer"><code>Scanner</code></a>. You can use it just like the <code>BufferedReader</code>:

<pre><code>Scanner scanner = new Scanner(myString);
while (scanner.hasNextLine()) {
 String line = scanner.nextLine();
 // process the line
}
scanner.close();
</code></pre>

I think that this is a bit cleaner approach that both of the suggested ones.

blocks|key|1294782|text|也可以使用String的split方法：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1294783|String[]+lines+=+myString.split(System.getProperty("line.separator"));|code-block|syntax|javascript|1294784|这为您提供了一个方便的数组中的所有行。|1294785|我不知道split的表现如何。它使用正则表达式。|1294786|entityMap^0|C|5|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|V|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

You can also use the <code>split</code> method of String:

<pre><code>String[] lines = myString.split(System.getProperty("line.separator"));
</code></pre>

This gives you all lines in a handy array. 

I don't know about the performance of split. It uses regular expressions.

blocks|key|1294857|text|使用Apache+Commons+IOUtils，您可以很好地通过|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1294858|List<String>+lines+=+IOUtils.readLines(new+StringReader(string));|code-block|syntax|javascript|1294859|它没有做任何聪明的事情，但它很好和紧凑。它也可以处理流，如果你愿意，你也可以得到一个LineIterator。|style|CODE|1294860|entityMap|0|LINK|mutability|MUTABLE|url|http://commons.apache.org/proper/commons-io/javadocs/api-release/org/apache/commons/io/IOUtils.html^0|2|M|0|0|0|16|C|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@$A|10|B|11|K|L]]|9|@]|C|$]]|$1|M|3|-4|5|6|7|12|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

Using <a href="http://commons.apache.org/proper/commons-io/javadocs/api-release/org/apache/commons/io/IOUtils.html" rel="noreferrer">Apache Commons IOUtils</a> you can do this nicely via

<pre><code>List&lt;String&gt; lines = IOUtils.readLines(new StringReader(string));
</code></pre>

It's not doing anything clever, but it's nice and compact. It'll handle streams as well, and you can get a <code>LineIterator</code> too if you prefer.

blocks|key|1509529|text|您还可以使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1509530|String[]+lines+=+someString.split("\n");|code-block|syntax|javascript|1509531|如果这不起作用，请尝试用\r\n替换\n。|offset|length|style|CODE|1509532|entityMap^0|0|0|C|4|I|2|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

You can also use:

<pre><code>String[] lines = someString.split("\n");
</code></pre>

If that doesn't work try replacing <code>\n</code> with <code>\r\n</code>.

blocks|key|1294999|text|因为我对效率的角度特别感兴趣，所以我创建了一个小测试类(如下所示)。5,000,000行结果：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1295000|Comparing+line+breaking+performance+of+different+solutions
Testing+5000000+lines
Split+(all):+14665+ms
Split+(CR+only):+3752+ms
Scanner:+10005
Reader:+2060|code-block|syntax|javascript|1295001|像往常一样，确切的时间可能会有所不同，但无论我运行它的频率如何，这个比率都是正确的。|1295002|结论:+OP的“更简单”和“更高效”的需求不可能同时得到满足，split解决方案(无论是哪一种实现)都更简单，但是Reader实现无疑要比其他实现更好。|offset|length|style|CODE|1295003|import+java.io.BufferedReader;
import+java.io.IOException;
import+java.io.StringReader;
import+java.util.ArrayList;
import+java.util.List;
import+java.util.Scanner;

/**
+*+Test+class+for+splitting+a+string+into+lines+at+linebreaks
+*/
public+class+LineBreakTest+{
++++/**+Main+method:+pass+in+desired+line+count+as+first+parameter+(default+=+10000).+*/
++++public+static+void+main(String[]+args)+{
++++++++int+lineCount+=+args.length+==+0+?+10000+:+Integer.parseInt(args[0]);
++++++++System.out.println("Comparing+line+breaking+performance+of+different+solutions");
++++++++System.out.printf("Testing+%25d+lines%25n",+lineCount);
++++++++String+text+=+createText(lineCount);
++++++++testSplitAllPlatforms(text);
++++++++testSplitWindowsOnly(text);
++++++++testScanner(text);
++++++++testReader(text);
++++}

++++private+static+void+testSplitAllPlatforms(String+text)+{
++++++++long+start+=+System.currentTimeMillis();
++++++++text.split("\n\r%7C\r");
++++++++System.out.printf("Split+(regexp):+%25d%25n",+System.currentTimeMillis()+-+start);
++++}

++++private+static+void+testSplitWindowsOnly(String+text)+{
++++++++long+start+=+System.currentTimeMillis();
++++++++text.split("\n");
++++++++System.out.printf("Split+(CR+only):+%25d%25n",+System.currentTimeMillis()+-+start);
++++}

++++private+static+void+testScanner(String+text)+{
++++++++long+start+=+System.currentTimeMillis();
++++++++List<String>+result+=+new+ArrayList<>();
++++++++try+(Scanner+scanner+=+new+Scanner(text))+{
++++++++++++while+(scanner.hasNextLine())+{
++++++++++++++++result.add(scanner.nextLine());
++++++++++++}
++++++++}
++++++++System.out.printf("Scanner:+%25d%25n",+System.currentTimeMillis()+-+start);
++++}

++++private+static+void+testReader(String+text)+{
++++++++long+start+=+System.currentTimeMillis();
++++++++List<String>+result+=+new+ArrayList<>();
++++++++try+(BufferedReader+reader+=+new+BufferedReader(new+StringReader(text)))+{
++++++++++++String+line+=+reader.readLine();
++++++++++++while+(line+!=+null)+{
++++++++++++++++result.add(line);
++++++++++++++++line+=+reader.readLine();
++++++++++++}
++++++++}+catch+(IOException+exc)+{
++++++++++++//+quit
++++++++}
++++++++System.out.printf("Reader:+%25d%25n",+System.currentTimeMillis()+-+start);
++++}

++++private+static+String+createText(int+lineCount)+{
++++++++StringBuilder+result+=+new+StringBuilder();
++++++++StringBuilder+lineBuilder+=+new+StringBuilder();
++++++++for+(int+i+=+0;+i+<+20;+i%2B%2B)+{
++++++++++++lineBuilder.append("word+");
++++++++}
++++++++String+line+=+lineBuilder.toString();
++++++++for+(int+i+=+0;+i+<+lineCount;+i%2B%2B)+{
++++++++++++result.append(line);
++++++++++++result.append("\n");
++++++++}
++++++++return+result.toString();
++++}
}|1295004|entityMap^0|0|0|0|V|5|1L|6|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|V|8|@$K|W|L|X|M|N]|$K|Y|L|Z|M|N]]|9|@]|A|$]]|$1|O|3|P|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|R|$]]

Since I was especially interested in the efficiency angle, I created a little test class (below). Outcome for 5,000,000 lines:

<pre><code>Comparing line breaking performance of different solutions
Testing 5000000 lines
Split (all): 14665 ms
Split (CR only): 3752 ms
Scanner: 10005
Reader: 2060
</code></pre>

As usual, exact times may vary, but the ratio holds true however often I've run it.

Conclusion: the "simpler" and "more efficient" requirements of the OP can't be satisfied simultaneously, the <code>split</code> solution (in either incarnation) is simpler, but the <code>Reader</code> implementation beats the others hands down.

<pre><code>import java.io.BufferedReader;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

/**
 * Test class for splitting a string into lines at linebreaks
 */
public class LineBreakTest {
 /** Main method: pass in desired line count as first parameter (default = 10000). */
 public static void main(String[] args) {
 int lineCount = args.length == 0 ? 10000 : Integer.parseInt(args[0]);
 System.out.println("Comparing line breaking performance of different solutions");
 System.out.printf("Testing %d lines%n", lineCount);
 String text = createText(lineCount);
 testSplitAllPlatforms(text);
 testSplitWindowsOnly(text);
 testScanner(text);
 testReader(text);
 }

 private static void testSplitAllPlatforms(String text) {
 long start = System.currentTimeMillis();
 text.split("\n\r|\r");
 System.out.printf("Split (regexp): %d%n", System.currentTimeMillis() - start);
 }

 private static void testSplitWindowsOnly(String text) {
 long start = System.currentTimeMillis();
 text.split("\n");
 System.out.printf("Split (CR only): %d%n", System.currentTimeMillis() - start);
 }

 private static void testScanner(String text) {
 long start = System.currentTimeMillis();
 List&lt;String&gt; result = new ArrayList&lt;&gt;();
 try (Scanner scanner = new Scanner(text)) {
 while (scanner.hasNextLine()) {
 result.add(scanner.nextLine());
 }
 }
 System.out.printf("Scanner: %d%n", System.currentTimeMillis() - start);
 }

 private static void testReader(String text) {
 long start = System.currentTimeMillis();
 List&lt;String&gt; result = new ArrayList&lt;&gt;();
 try (BufferedReader reader = new BufferedReader(new StringReader(text))) {
 String line = reader.readLine();
 while (line != null) {
 result.add(line);
 line = reader.readLine();
 }
 } catch (IOException exc) {
 // quit
 }
 System.out.printf("Reader: %d%n", System.currentTimeMillis() - start);
 }

 private static String createText(int lineCount) {
 StringBuilder result = new StringBuilder();
 StringBuilder lineBuilder = new StringBuilder();
 for (int i = 0; i &lt; 20; i++) {
 lineBuilder.append("word ");
 }
 String line = lineBuilder.toString();
 for (int i = 0; i &lt; lineCount; i++) {
 result.append(line);
 result.append("\n");
 }
 return result.toString();
 }
}
</code></pre>

blocks|key|1295035|text|从Java11开始，出现了一种新的方法String.lines|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1295036|/**
+*+Returns+a+stream+of+lines+extracted+from+this+string,
+*+separated+by+line+terminators.
+*+...
+*/
public+Stream<String>+lines()+{+...+}|code-block|syntax|javascript|1295037|用法：|1295038|"line1\nline2\nlines3"
++++.lines()
++++.forEach(System.out::println);|1295039|entityMap^0|J|C|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

Since Java 11, there is a new method <code>String.lines</code>:

<pre><code>/**
 * Returns a stream of lines extracted from this string,
 * separated by line terminators.
 * ...
 */
public Stream&lt;String&gt; lines() { ... }
</code></pre>

Usage:

<pre><code>"line1\nline2\nlines3"
 .lines()
 .forEach(System.out::println);
</code></pre>

blocks|key|1295093|text|或者结合使用新的try+with+resources子句和Scanner：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1295094|+++try+(Scanner+scanner+=+new+Scanner(value))+{
++++++++while+(scanner.hasNextLine())+{
++++++++++++String+line+=+scanner.nextLine();
++++++++++++//+process+the+line
++++++++}
++++}|code-block|syntax|javascript|1295095|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Or use new try with resources clause combined with Scanner:

<pre><code> try (Scanner scanner = new Scanner(value)) {
 while (scanner.hasNextLine()) {
 String line = scanner.nextLine();
 // process the line
 }
 }
</code></pre>

blocks|key|1509790|text|您可以使用stream+api和包装在BufferedReader中的StringReader，它在java8中获得了lines()流输出：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1509791|import+java.util.stream.*;
import+java.io.*;
class+test+{
++++public+static+void+main(String...+a)+{
++++++++String+s+=+"this+is+a+\nmultiline\rstring\r\nusing+different+newline+styles";

++++++++new+BufferedReader(new+StringReader(s)).lines().forEach(
++++++++++++(line)+->+System.out.println("one+line+of+the+string:+"+%2B+line)
++++++++);
++++}
}|code-block|syntax|javascript|1509792|给出|1509793|one+line+of+the+string:+this+is+a
one+line+of+the+string:+multiline
one+line+of+the+string:+string
one+line+of+the+string:+using+different+newline+styles|1509794|就像BufferedReader的readLine一样，换行符本身不包括在内。支持所有类型的换行分隔符(甚至在同一字符串中)。|1509795|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You can use the stream api and a StringReader wrapped in a BufferedReader which got a lines() stream output in java 8:

<pre><code>import java.util.stream.*;
import java.io.*;
class test {
 public static void main(String... a) {
 String s = "this is a \nmultiline\rstring\r\nusing different newline styles";

 new BufferedReader(new StringReader(s)).lines().forEach(
 (line) -&gt; System.out.println("one line of the string: " + line)
 );
 }
}
</code></pre>

Gives

<pre><code>one line of the string: this is a
one line of the string: multiline
one line of the string: string
one line of the string: using different newline styles
</code></pre>

Just like in BufferedReader's readLine, the newline character(s) themselves are not included. All kinds of newline separators are supported (in the same string even).

blocks|key|1295195|text|使用Stream+API和Method+references等Java+8功能的解决方案|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1295196|new+BufferedReader(new+StringReader(myString))
++++++++.lines().forEach(System.out::println);|code-block|syntax|javascript|1295197|或|1295198|public+void+someMethod(String+myLongString)+{

++++new+BufferedReader(new+StringReader(myLongString))
++++++++++++.lines().forEach(this::parseString);
}

private+void+parseString(String+data)+{
++++//do+something
}|1295199|entityMap^0|2|A|D|H|V|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

Solution using <code>Java 8</code> features such as <code>Stream API</code> and <code>Method references</code>

<pre><code>new BufferedReader(new StringReader(myString))
 .lines().forEach(System.out::println);
</code></pre>

or

<pre><code>public void someMethod(String myLongString) {

 new BufferedReader(new StringReader(myLongString))
 .lines().forEach(this::parseString);
}

private void parseString(String data) {
 //do something
}
</code></pre>

blocks|key|1295247|text|最简单、最通用的方法是使用匹配Any+Unicode+linebreak+sequence的正则表达式Linebreak+matcher+\R|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1295248|Pattern+NEWLINE+=+Pattern.compile("\\R")
String+lines[]+=+NEWLINE.split(input)|code-block|syntax|javascript|1295249|@查看https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/regex/Pattern.html|1295250|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/regex/Pattern.html^0|F|U|1F|H|1X|2|0|0|3|2H|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|D|@$9|13|A|14|1|15]]|E|$]]|$1|M|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

The easiest and most universal approach would be to just use the regex <code>Linebreak matcher</code> <code>\R</code> which matches <code>Any Unicode linebreak sequence</code>:

<pre><code>Pattern NEWLINE = Pattern.compile("\\R")
String lines[] = NEWLINE.split(input)
</code></pre>

@see <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/regex/Pattern.html" rel="nofollow noreferrer">https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/regex/Pattern.html</a>

Given a string that isn't too long, what is the best way to read it line by line?

I know you can do:

<pre><code>BufferedReader reader = new BufferedReader(new StringReader(&lt;string&gt;));
reader.readLine();
</code></pre>

Another way would be to take the substring on the eol:

<pre><code>final String eol = System.getProperty("line.separator");
output = output.substring(output.indexOf(eol + 1));
</code></pre>

Any other maybe simpler ways of doing it? I have no problems with the above approaches, just interested to know if any of you know something that may look simpler and more efficient?

Read String line by line

Java

给定一个不太长的字符串，逐行阅读它的最佳方法是什么？我知道你能做到：BufferedReader reader = new BufferedReader(new StringReader(<string>));reader.readLine();另一种方法是获取eol上的子字符串：final String eol = ...

问逐行读取字符串
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