JDK5.0允许java像C语言那样直接用printf()方法来格式化输出

System.out.format()功能与printf()一样，可以使用%d,%f等参数。

使用System.out.format()完成左对齐，补0，千位分隔符，小数点位数，本地化表达

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public class TestNumber {          public static void main(String[] args) {         int year = 2020;         //左对齐，补0，千位分隔符，小数点位数，本地化表达                 //直接打印数字         System.out.println(year);                     //直接打印数字         System.out.format("%d%n",year);         //总长度是8,默认右对齐         System.out.format("%8d%n",year);         //总长度是8,左对齐         System.out.format("%-8d%n",year);         //总长度是8,不够补0         System.out.format("%08d%n",year);         //千位分隔符         System.out.format("%,8d%n",year*10000);             //保留5位小数         System.out.format("%.5f%n",Math.PI);                     //不同国家的千位分隔符         System.out.format(Locale.FRANCE,"%,.2f%n",Math.PI*10000);         System.out.format(Locale.US,"%,.2f%n",Math.PI*10000);         System.out.format(Locale.UK,"%,.2f%n",Math.PI*10000);                 } }

 输出结果：

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2020 2020     2020 2020    00002020 20,200,000 3.14159 31?415,93 31,415.93 31,415.93