Java Math数字处理类与包装类习题

//创建Integer类对象，并以int型返回
Integer intAb = new Integer("123");
System.out.println(intAb.intValue());

//创建两个Character对象，相应转换后判断是否相等
Character charA = new Character('a');
Character charB = new Character('A');
System.out.println("charA = "+charA + "  "+"charB = "+charB);
System.out.println(charA.equals(charB));
charA = Character.toLowerCase(charA);
charB = Character.toLowerCase(charB);
System.out.println(charA.equals(charB));

//建立两个Boolean型变量，注意输出
Boolean boolA = new Boolean("true");
Boolean boolB = new Boolean("asd");
Boolean boolC = new Boolean("True");
System.out.println(boolA);
System.out.println(boolB);
System.out.println(boolC);

//输出2~32之间6个偶数的和
int sum = 0;
int j = 0;
Random ra = new Random();
while(true){
int kk = 2 + ra.nextInt(30);
if(kk % 2 == 0){
sum += kk;
j++;
}
if(j == 6)
break;
}
System.out.println(sum);

//求园面积 结果保留5位小数
double ymj = Math.PI*Math.pow(2.14, 2);
DecimalFormat df1 = new DecimalFormat();
df1.applyPattern(".00000");
System.out.println(df1.format(ymj));

//输出5个四位随机数
String str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
for(int k = 0; k < 5; k++){
String strA = "";
for(int i = 1; i <= 4; i++){
Random ran = new Random();
int sui = ran.nextInt(36);//Random 0~36不会包括36的
strA += str.substring(sui,sui+1);
}
System.out.println(strA);
}

//使用StringBuilder附加字符串
for(int k = 0; k < 5; k++){
StringBuilder strA = new StringBuilder();
for(int i = 1; i <= 4; i++){
Random ran = new Random();
int sui = ran.nextInt(36);//Random 0~36不会包括36的
strA.append(str.substring(sui,sui+1));
}
System.out.println(strA);
}