package baseDemo1;

/**

* printf的一些常用的打印格式总结

* @author chen 2014年11月27日16:26:07

* */

public class PrintfDemo {

public static void main(String[] args) {

String str = "I like data mining";

int i = 1234;

double d = 3.14159265358979;

float f1 = -0.123456f;

float f2 = 0.123456f;

System.out.printf("1，str = %20s\n", str); //String类型

System.out.printf("2，i = %d\n", i); //int类型

System.out.printf("3，d = %f\n", d); //double类型，默认小数是6位

/*10表示输出的长度，从右至左所有数字和字符的长度，

如果字符没有10个，则左边补上空格；若大于10个，字符全部打印出来*/

System.out.printf("4，d = %10f\n", d);

System.out.printf("5，d = %.2f\n", d); //.2表示小数点的位数

System.out.printf("6，f1 = %f\n", f1); //flaot类型

System.out.printf("7，f2 = %f\n", f2); //float类型，正数的时候，无符号

System.out.printf("8，f2 = %+f\n", f2); //float类型，正数的时候，显示数字的符号

System.out.printf("9，%%"); //打印“%”，只写一个%会报错

System.out.println();

System.out.println("");

PrintfDemo.nineNine();

}

/**

* Description:打印九九乘法表

* */

static void nineNine(){

for (int i = 1; i < 10; i++){

for (int j = 1; j <= i; j++){

System.out.printf("%d*%d =%2d ", i, j, i*j);

}

System.out.println();

}

}

}

打印结果：

1，str = I like data mining

2，i = 1234

3，d = 3.141593

4，d = 3.141593

5，d = 3.14

6，f1 = -0.123456

7，f2 = 0.123456

8，f2 = +0.123456

9，%

1*1 = 1

2*1 = 2 2*2 = 4

3*1 = 3 3*2 = 6 3*3 = 9

4*1 = 4 4*2 = 8 4*3 =12 4*4 =16

5*1 = 5 5*2 =10 5*3 =15 5*4 =20 5*5 =25

6*1 = 6 6*2 =12 6*3 =18 6*4 =24 6*5 =30 6*6 =36

7*1 = 7 7*2 =14 7*3 =21 7*4 =28 7*5 =35 7*6 =42 7*7 =49

8*1 = 8 8*2 =16 8*3 =24 8*4 =32 8*5 =40 8*6 =48 8*7 =56 8*8 =64

9*1 = 9 9*2 =18 9*3 =27 9*4 =36 9*5 =45 9*6 =54 9*7 =63 9*8 =72 9*9 =81