Java中是否有类似于.NET的String.Format
的功能?
String.Format("{0} -- {1} -- {2}", ob1, ob2, ob3)
等同于Java的
String.format("%1$s -- %2$s -- %3$s", ob1, ob2, ob3)
http://download.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html#syntax
Calendar c = new GregorianCalendar(1995, MAY, 23);
String s = String.format("Duke's Birthday: %1$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"
有一个MessageFormat.format()
函数,它使用 .net 符号。
由于索引是可选参数,因此您还可以简单地使用字符串 %s
。
String name = "Jon";
int age = 26;
String.format("%s is %s years old.", name, age);
在我看来,上面的例子更加简洁。
有关java文档中%s
的说明:
如果参数arg为null,则结果为“null”。如果arg实现了Formattable,则会调用arg.formatTo。否则,通过调用arg.toString()方法获取结果。
这并不是对OP问题的真正回答,但可能对其他正在寻找一种简单方法将字符串替换为包含C#风格“格式项”的字符串的人有所帮助。
/**
* 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();
}