英文:
Why java System.out.print method have various forms?
问题
public void print(long l) {
write(String.valueOf(l));
}
/**
* 打印浮点数。由<code>{@link
* java.lang.String#valueOf(float)}</code>生成的字符串根据平台的默认字符编码转换为字节，
* 并以与<code>{@link #write(int)}</code>方法完全相同的方式写入这些字节。
*
* @param f 要打印的<code>float</code>
* @see java.lang.Float#toString(float)
*/
public void print(float f) {
write(String.valueOf(f));
}
/**
* 打印双精度浮点数。由<code>{@link java.lang.String#valueOf(double)}</code>生成的字符串根据
* 平台的默认字符编码转换为字节，然后以与<code>{@link #write(int)}</code>方法完全相同的方式写入这些字节。
*
* @param d 要打印的<code>double</code>
* @see java.lang.Double#toString(double)
*/
public void print(double d) {
write(String.valueOf(d));
}
/**
* 打印字符数组。将字符转换为字节，根据平台的默认字符编码，以与<code>{@link #write(int)}</code>方法
* 完全相同的方式写入这些字节。
*
* @param s 要打印的字符数组
*
* @throws NullPointerException 如果<code>s</code>为<code>null</code>
*/
public void print(char s[]) {
write(s);
}
请注意，这只是代码的翻译部分，不包括您提供的问题或其他内容。
英文:
public void print(long l) {
write(String.valueOf(l));
}
/**
* Prints a floating-point number. The string produced by <code>{@link
* java.lang.String#valueOf(float)}</code> is translated into bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param f The <code>float</code> to be printed
* @see java.lang.Float#toString(float)
*/
public void print(float f) {
write(String.valueOf(f));
}
/**
* Prints a double-precision floating-point number. The string produced by
* <code>{@link java.lang.String#valueOf(double)}</code> is translated into
* bytes according to the platform's default character encoding, and these
* bytes are written in exactly the manner of the <code>{@link
* #write(int)}</code> method.
*
* @param d The <code>double</code> to be printed
* @see java.lang.Double#toString(double)
*/
public void print(double d) {
write(String.valueOf(d));
}
/**
* Prints an array of characters. The characters are converted into bytes
* according to the platform's default character encoding, and these bytes
* are written in exactly the manner of the
* <code>{@link #write(int)}</code> method.
*
* @param s The array of chars to be printed
*
* @throws NullPointerException If <code>s</code> is <code>null</code>
*/
public void print(char s[]) {
write(s);
}
I opened java.io.PrintStream class file. And i found there are various print methods. Each method 99% same without only parameter type. Many programming guide books suggest that you can use generic(or template) in this situation. So i'm wondering why java.io.Printstream do not use generic.
答案1
得分: 1
如果您要使用以下方法：
public <T> void print(T value);
并且您想要打印一个 int 值，那么它将被用作：
public void print(Integer value);
因此，int 值将被装箱，这意味着性能下降和不必要的内存使用。
这就是为什么通常会为所有原始数据类型提供方法重载的原因。
另外，正如Taschi指出的，这个类只是比Java中的泛型更旧。
英文:
If you would use a method with
public <T> void print(T value);
and you would want to print an int value then if would be used as
public void print(Integer value);
so the int value would be boxed what means lost in performance and unnecessary memory usage.
That is the reason that you will often find method overloads for all primitiv data-types
Also as Taschi pointed out, the class is simply older than generics in Java.
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