你可以使用scala-code，它与java兼容，并且允许用""" "括起来的多行字符串:

package foobar
object SWrap {
  def bar = """John said: "This is
  a test
  a bloody test,
  my dear." and closed the door.""" 
}

(注意字符串内的引号)和来自java:

String s2 = foobar.SWrap.bar ();

这样是否更舒服?

另一种方法，如果你经常处理长文本，应该放在你的源代码中，可能是一个脚本，它从外部文件中获取文本，并将其包装为一个多行java- string，像这样:

sed '1s/^/String s = \"/;2,$s/^/\t+ "/;2,$s/$/"/' file > file.java

这样你就可以很容易地复制粘贴到你的源代码中。

遗憾的是，Java没有多行字符串字面量。您要么必须连接字符串字面量(使用+或StringBuilder是最常见的两种方法)，要么从单独的文件中读取字符串。

对于大的多行字符串文字，我倾向于使用一个单独的文件，并使用getResourceAsStream() (Class类的一个方法)读取它。这使得查找文件变得很容易，因为您不必担心当前目录与代码安装的位置。它还使打包更容易，因为您实际上可以将文件存储在jar文件中。

假设你在一个名为Foo的类中。就像这样做:

Reader r = new InputStreamReader(Foo.class.getResourceAsStream("filename"), "UTF-8");
String s = Utils.readAll(r);

另一个烦恼是Java没有标准的“将这个Reader中的所有文本读入字符串”方法。写起来很简单:

public static String readAll(Reader input) {
    StringBuilder sb = new StringBuilder();
    char[] buffer = new char[4096];
    int charsRead;
    while ((charsRead = input.read(buffer)) >= 0) {
        sb.append(buffer, 0, charsRead);
    }
    input.close();
    return sb.toString();
}

注意:这个答案适用于Java 14及以上版本。

Java 15引入了文本块(多行文字)。详情请看这个答案。

听起来像是要做一个多行文字，这在Java中是不存在的。

你最好的选择是用+ d组合的字符串。人们提到的一些其他选项(StringBuilder, String。format, String.join)只有当你从一个字符串数组开始时才更可取。

考虑一下:

String s = "It was the best of times, it was the worst of times,\n"
         + "it was the age of wisdom, it was the age of foolishness,\n"
         + "it was the epoch of belief, it was the epoch of incredulity,\n"
         + "it was the season of Light, it was the season of Darkness,\n"
         + "it was the spring of hope, it was the winter of despair,\n"
         + "we had everything before us, we had nothing before us";

与StringBuilder:

String s = new StringBuilder()
           .append("It was the best of times, it was the worst of times,\n")
           .append("it was the age of wisdom, it was the age of foolishness,\n")
           .append("it was the epoch of belief, it was the epoch of incredulity,\n")
           .append("it was the season of Light, it was the season of Darkness,\n")
           .append("it was the spring of hope, it was the winter of despair,\n")
           .append("we had everything before us, we had nothing before us")
           .toString();

与String.format ():

String s = String.format("%s\n%s\n%s\n%s\n%s\n%s"
         , "It was the best of times, it was the worst of times,"
         , "it was the age of wisdom, it was the age of foolishness,"
         , "it was the epoch of belief, it was the epoch of incredulity,"
         , "it was the season of Light, it was the season of Darkness,"
         , "it was the spring of hope, it was the winter of despair,"
         , "we had everything before us, we had nothing before us"
);

相对于Java8 String.join():

String s = String.join("\n"
         , "It was the best of times, it was the worst of times,"
         , "it was the age of wisdom, it was the age of foolishness,"
         , "it was the epoch of belief, it was the epoch of incredulity,"
         , "it was the season of Light, it was the season of Darkness,"
         , "it was the spring of hope, it was the winter of despair,"
         , "we had everything before us, we had nothing before us"
);

如果您想在特定的系统中使用换行符，您要么需要使用system . lineseparator()，要么可以在String.format中使用%n。

另一种选择是将资源放在文本文件中，只读取该文件的内容。对于非常大的字符串，这将是可取的，以避免不必要地膨胀您的类文件。

使用JDK/12早期访问构建# 12，现在可以在Java中使用多行字符串，如下所示:

String multiLine = `First line
    Second line with indentation
Third line
and so on...`; // the formatting as desired
System.out.println(multiLine);

这将导致以下输出:

第一行 第二行有缩进 第三行 等等……

编辑: 推迟至java 13

在Eclipse中，如果你打开选项“在粘贴到字符串文字时转义文本”(在Preferences > Java > Editor > Typing中)并在引号中粘贴一个多行字符串，它将自动为你的所有行添加“和\n”+。

String str = "paste your text here";

看到所有的答案，我认为没有人提到比在java的新版本，你可以这样做:

String s = """
    This
    is 
    a
    multiline
    string
    """;
System.out.println(s);

这是它打印的内容:

This
is
a
multiline
string