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);
		}