代码如下，随便附一句，一定要看写的源码，我已经尽量马马虎虎的写了，你更容易看懂。
public class Test {
// 第八题
public static final int NUM = 100;
public static final double GOOD = 99.99;
public static final String CLASSNAME = "Test.Class";
public static final long MAX = 9999999;
public static void main(String[] args) {
// 第一题
byte byte1 = 1;
short short1 = 1;
int int1 = 1;
long long1 = 1;
float float1 = 1;
double double1 = 1.0;
System.out.println("byte1 - " + byte1);
System.out.println("short1 - " + short1);
System.out.println("int1 - " + int1);
System.out.println("long1 - " + long1);
System.out.println("float1 - " + float1);
System.out.println("double1 - " + double1);
// 第二题
String name;
char sex;
int age;
boolean isMember;
// 第三题
int score1;
double score2 = 98.5;
// 第四题
double f1 = 10.1, f2 = 34.2;
System.out.println("f1，f2的和:" + (f1 + f2));
System.out.println("f1，f2的差:" + (f1 - f2));
System.out.println("f1，f2的积:" + (f1 * f2));
System.out.println("f1，f2的商:" + (f1 / f2));
// 第五题
int f3 = 5;
double f4 = 45.6;
System.out.println("f3，f4的和:" + (f3 + f4));
System.out.println("f3，f4的差:" + (f3 - f4));
System.out.println("f3，f4的积:" + (f3 * f4));
System.out.println("f3，f4的商:" + (f3 / f4));
// 第六题
int A = 65;
char a = (char) A;
System.out.println("整型互转char:" + a);
// 第七题
double timor = 123.456789;
int x = Integer
.parseInt(new java.text.DecimalFormat("0").format(timor));// 四舍五入
System.out.println("double -> int :" + x);
// 第八题(定义在最开始)
System.out.println("常量NUM的值: " + NUM);
System.out.println("常量GOOD的值: " + GOOD);
System.out.println("常量CLASSNAME的值: " + CLASSNAME);
System.out.println("常量MAX的值: " + MAX);
// 第九题(自定义商品类)
class Goods {
private String name;
private double price;
private int count;
private double total;
public Goods(String name, double price, int count) {
this.name = name;
this.price = price;
this.count = count;
}
public void print() {
total = price * count;
System.out.println("商品名 价格 数量 总价");
System.out.println(name + " " + price + " " + count + " "
+ total);
}
}
Goods goods = new Goods("苹果", 2, 10);
goods.print();
// 第十题
double pi = 3.14, r, d;
r = 4;
d = 2 * r;
System.out.println("圆的周长: " + (pi * d));
System.out.println("圆的面积: " + (pi * r * r));
// 第十一题
String qqname = "1234567890";
String qqpassword = "asd!#@#$%66";
Date birth = new Date(2014, 5, 1);
boolean isVIP = false;
char sex1 = '男';
StringBuilder personInfo = new StringBuilder();
personInfo.append("我是一个快乐的骚年");
personInfo
.append("然后a!#$%^&*asdasdasdasdsa9d87a9s8d79asdjidauisdhausdihiasd");
// 第十二题
class Swaper {
public void change(int num1, int num2) {
int temp = num1;
num1 = num2;
num2 = temp;
System.out.printf("a=%d,b=%d\n", num1, num2);
}
}
int a1 = 2;
int b1 = 5;
Swaper swaper = new Swaper();
swaper.change(a1, b1);
}
}