课后作业

 

public class EnumTest {

 

public static void main(String[] args) {

Size s=Size.SMALL;

Size t=Size.LARGE;

//s和t引用同一个对象？

System.out.println(s==t);  //

//是原始数据类型吗？

System.out.println(s.getClass().isPrimitive());

//从字符串中转换

Size u=Size.valueOf("SMALL");

System.out.println(s==u);  //true

//列出它的所有值

for(Size value:Size.values()){

System.out.println(value);

}

}

 

}

 enum Size{SMALL,MEDIUM,LARGE};

运行结果：false
false
true
SMALL
MEDIUM
LARGE

 

 

public class Bit {

    public static void main(String[] args) {

        int num1 = 8; // 正数

        int num2 = -8; // 负数

 

        // 按位取反

        int complement1 = ~num1;

        int complement2 = ~num2;

 

        // 按位与

        int andResult = num1 & num2;

 

        // 按位或

        int orResult = num1 | num2;

 

        // 按位异或

        int xorResult = num1 ^ num2;

 

        // 输出结果

        System.out.println("按位取反:");

        System.out.println(" ~" + num1 + " = " + complement1);

        System.out.println(" ~" + num2 + " = " + complement2);

        System.out.println();

 

        System.out.println("按位与:");

        System.out.println(num1 + " & " + num2 + " = " + andResult);

        System.out.println();

 

        System.out.println("按位或:");

        System.out.println(num1 + " | " + num2 + " = " + orResult);

        System.out.println();

 

        System.out.println("按位异或:");

        System.out.println(num1 + " ^ " + num2 + " = " + xorResult);

    }

}

 

 

public class Test {

private static int value=1;

public static void main(String[] args) {

int value=2;

System.out.println(value);

}

}

最后输出2

 

 

int X=100;

int Y=200;

System.*out*.println("X+Y="+X+Y);

System.*out*.println(X+Y+"=X+Y");

代码的结果：X+Y=100200

 

 

public static class Main{
    public static void main(String[] args) {
        System.out.println("0.51+0.1="+(0.51+0.01));
        System.out.println("1.0-0.42="+(1.0-0.42));
        System.out.println("4.015*100="+(4.015*100));
        System.out.println("123.3/100="+(123.3/100));
    }
}最后得到的结果是

0.51+0.1=0.52
1.0-0.42=0.5800000000000001
4.015*100=401.49999999999994
123.3/100=1.2329999999999999