Java输出格式化之占位符

import java.text.MessageFormat;
import java.util.Date;
 
public class test01 {
 
    public static void main(String[] args) {
        System.out.println("hello");// print hello
 
        // %s占位符,输出字符串
        String username = "user1";
        int num = 3;
        System.out.printf("%s您好,您是第%s位访客\n", username, num); // prints user1您好,您是第3位访客
 
        // %f占位符
        double d = 1.2;
        float f = 1.2f;
        System.out.printf("%f %f", d, f); // prints 1.200000 1.200000
        
 
        // %1$s占位符
        //%n$ms：代表输出的是字符串，n代表是第几个参数，设置m的值可以在输出之前放置空格，也可以设为0m,在输出之前放置m个0 
        System.out.println(String.format("我是%1$s,我来自%2$s,今年%3$s岁", "中国人", "北京","22"));
        // prints 我是中国人,我来自北京,今年22岁
        
 
        // {}占位符，{}内的数字代表第几个参数，参数从0开始
        String url = "www.baidu.com";
        int count = 1000;
        System.out.println(MessageFormat.format("该网站{0}被访问了 {1} 次.", url, count));
        // prints 该网站www.baidu.com被访问了 1,000 次.
 
 
        // {}占位符
        String template = "Welcome {0}!  Your last login was {1}";
        String output = MessageFormat.format(template, new Object[] { "Python",new Date().toString() });
        System.out.println(output);
        // prints  Welcome Python!  Your last login was Fri Oct 10 20:47:00 CST 2014
 
    }
 
}