Java相当于.NET的String.Format

Question

Java中有.NET的String.Format吗？

Answer 1

对此的10美分答案是：

C＃的

String.Format("{0} -- {1} -- {2}", ob1, ob2, ob3)

相当于Java的

String.format("%1$s -- %2$s -- %3$s", ob1, ob2, ob3)

注意基于1的索引，“s”表示使用.toString（）转换为字符串。 还有许多其他转换和格式选项：

http://download.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html#syntax

Answer 2

看看String.format和PrintStream.format方法。

两者都基于java.util.Formatter类 。

String.format示例：

Calendar c = new GregorianCalendar(1995, MAY, 23);
String s = String.format("Duke's Birthday: %1$tm %1$te,%1$tY", c);
// -> s == "Duke's Birthday: May 23, 1995"

System.out.format示例：

// Writes a formatted string to System.out.
System.out.format("Local time: %tT", Calendar.getInstance());
// -> "Local time: 13:34:18"

Answer 3

MessageFormat.format()使用.net表示法。

Answer 4

您也可以简单地将%s用于字符串，因为索引是一个optionnal参数。

String name = "Jon";
int age = 26;
String.format("%s is %s years old.", name, age);

它不那么吵了。

请注意java文档中的%s ：

如果参数arg为null，则结果为“null”。 如果arg实现了Formattable，则调用arg.formatTo。 否则，通过调用arg.toString（）获得结果。

Answer 5

Java中有一个String.format ，虽然语法与.NET略有不同。

Answer 6

这不是OP问题的真正答案，但对于那些正在寻找一种简单的方法来将字符串替换为包含C＃式“格式项”的字符串的人来说，这可能会有所帮助。

   /**
    * Method to "format" an array of objects as a single string, performing two possible kinds of
    * formatting:
    *
    * 1. If the first object in the array is a String, and depending on the number of objects in the
    *    array, then a very simplified and simple-minded C#-style formatting is done. Format items
    *    "{0}", "{1}", etc., are replaced by the corresponding following object, converted to string
    *    (of course). These format items must be as shown, with no fancy formatting tags, and only
    *    simple string substitution is done.
    *
    * 2. For the objects in the array that do not get processed by point 1 (perhaps all of them,
    *    perhaps none) they are converted to String and concatenated together with " - " in between.
    *
    * @param objectsToFormat  Number of objects in the array to process/format.
    * @param arrayOfObjects  Objects to be formatted, or at least the first objectsToFormat of them.
    * @return  Formatted string, as described above.
    */
   public static String formatArrayOfObjects(int objectsToFormat, Object... arrayOfObjects) {

      // Make a preliminary pass to avoid problems with nulls
      for (int i = 0; i < objectsToFormat; i++) {
         if (arrayOfObjects[i] == null) {
            arrayOfObjects[i] = "null";
         }
      }

      // If only one object, just return it as a string
      if (objectsToFormat == 1) {
         return arrayOfObjects[0].toString();
      }

      int nextObject = 0;
      StringBuilder stringBuilder = new StringBuilder();

      // If first object is a string it is necessary to (maybe) perform C#-style formatting
      if (arrayOfObjects[0] instanceof String) {
         String s = (String) arrayOfObjects[0];

         while (nextObject < objectsToFormat) {

            String formatItem = "{" + nextObject + "}";
            nextObject++;
            if (!s.contains(formatItem)) {
               break;
            }

            s = s.replace(formatItem, arrayOfObjects[nextObject].toString());
         }

         stringBuilder.append(s);
      }

      // Remaining objects (maybe all of them, maybe none) are concatenated together with " - "
      for (; nextObject < objectsToFormat; nextObject++) {
         if (nextObject > 0) {
            stringBuilder.append(" - ");
         }
         stringBuilder.append(arrayOfObjects[nextObject].toString());
      }

      return stringBuilder.toString();
   }

（如果你很好奇，我正在使用这段代码作为Android Log方法的简单包装器的一部分，以便更容易在单个日志消息中记录多个内容。）