[Java] 常用类-02 基础数据类型包装类 / Math 类

public class TestParser {
    public static void main(String[] args) {
        Integer i = new Integer(100);
        Double d = new Double("123.456");
        int j = i.intValue() + d.intValue();
        float f = i.floatValue() + d.floatValue();
        System.out.println(j);
        System.out.println(f);
        double pi = Double.parseDouble("3.1415926");
        double r = Double.valueOf("2.0").doubleValue();
        double s = pi * r * r;
        System.out.println(s);
        try {
            int k = Integer.parseInt("1.25");
        } catch (NumberFormatException e) {
            System.out.println("数据格式不对");
        }
        System.out.println(Integer.toBinaryString(123) + "B");
        System.out.println(Integer.toHexString(123) + "H");
        System.out.println(Integer.toOctalString(123) + "O");
    }
}
1111011B
7bH

173 O

public class ArrayParser {
    public static void main(String[] args) {
        double[][] d;
        String s = "1,2;3,4,5;6,7,8";
        String[] sFirst = s.split(";");
        d = new double[sFirst.length][];
        for (int i = 0; i < sFirst.length; i++) {
            String[] sSecond = sFirst[i].split(",");
            d[i] = new double[sSecond.length];
            for (int j = 0; j <sSecond.length; j++) {
                d[i][j] = Double.parseDouble(sSecond[j]);
            }
        }
        
        for (int i = 0; i <d.length; i++) {
            for (int j = 0; j < d[i].length; j++) {
                System.out.print(d[i][j] + " ");
            }
            System.out.println();
        }
    }
}
1.0 2.0 
3.0 4.0 5.0 
6.0 7.0 8.0 
public class TestMath {
    public static void main(String[] args) {
        double a = Math.random();
        double b = Math.random();
        System.out.println(Math.sqrt(a*a + b*b));
        System.out.println(Math.pow(a, 8));
        System.out.println(Math.round(b)); // re long
        System.out.println(Math.log(Math.pow(Math.E, 15)));
        double d = 60.0, r = Math.PI / 4;
        System.out.println(Math.toRadians(d));
        System.out.println(Math.toDegrees(r));  
    }
}
1.0152118816776885
0.004305269426978659
1
15.0
1.0471975511965976
45.0

posted @ 2013-12-02 16:40  小尼人00  阅读(149)  评论(0编辑  收藏  举报