java - 格式化包含许多字符串和整数的长 system.out.print

Question

假设您有以下内容:

String cake = "whatever";
int cakeNumber = 509;
String whyNot = "another string";
double number = 1;

system.out.println("I like "+ cake +" and I eat " + cakeNumber + " blah blah     prolonging this string because " + whyNot + " and so on " + number + ".");

所以，这没有多大意义，也没有必要，因为这只是一个例子。我的问题是，给定多个字符串和变量，它们之间有一个“加号”，它看起来像一团糟。没有办法格式化这个 println 或者通过减少加号的数量来稍微整理一下吗？

Answer 1

java.lang.StringBuilder

System.out.println(new StringBuilder("I like")
                   .append(cake)
                   .append(" and I eat ")
                   .append(cakeNumber)
                   .append(" blah blah     prolonging this string because ")
                   .append(whyNot)
                   .append(" and so on ")
                   .append(number)
                   .append(".")
                   .toString());

<小时/>

java.text.MessageFormat

System.out.println(MessageFormat.format("I like {0} and I eat {1} blah blah    prolonging this string because {2} and so on {3}.",
                   cake, cakeNumber, whyNot, number));

我有点喜欢静态导入，如下所示:

import static java.text.MessageFormat.format;

System.out.println(format("I like {0} and I eat {1} blah blah    prolonging this string because {2} and so on {3}.",
                   cake, cakeNumber, whyNot, number));

<小时/>

java.util.Formatter (也称为 String.format )

System.out.printf("I like %s and I eat %d blah blah    prolonging this string because %s and so on %f.%n",
                  cake, cakeNumber, whyNot, number);
                  

这里有很多语法可供选择(仅列出一些，可能还有更多):

System.out.format(...)
System.out.printf(...)
System.out.print(String.format(...)) // you will need to include the line break in the format
System.out.println(String.format(...)) // line break will be caused by println()
import static java.lang.String.format;
System.out.print(format(...))
System.out.println(format(...))
System.out.println(new Formatter().format(...))

%n 表示系统特定的换行符。这是必需的，因为 printf 不会在操作后自动插入换行符。

<小时/>

多行字符串连接

System.out.println("I like " + cake + " and I eat " +
                   cakeNumber + " blah blah    prolonging this string because" +
                   whyNot + " and so on " + number + ".");