package demo.client;
import java.lang.reflect.Field;
@SuppressWarnings("unused")
public class BasicClass {
	   public BasicClass() {
	        System.out.println("Java 8种基本类型详细信息");
	        System.out.println("=" + "=".repeat(50));
	        
	        // 1. 使用包装类的 TYPE 字段和 SIZE 常量
	        printBasicTypeInfo("byte", Byte.TYPE, Byte.BYTES, Byte.SIZE, Byte.MIN_VALUE, Byte.MAX_VALUE);
	        printBasicTypeInfo("short", Short.TYPE, Short.BYTES, Short.SIZE, Short.MIN_VALUE, Short.MAX_VALUE);
	        printBasicTypeInfo("int", Integer.TYPE, Integer.BYTES, Integer.SIZE, Integer.MIN_VALUE, Integer.MAX_VALUE);
	        printBasicTypeInfo("long", Long.TYPE, Long.BYTES, Long.SIZE, Long.MIN_VALUE, Long.MAX_VALUE);
	        printBasicTypeInfo("float", Float.TYPE, Float.BYTES, Float.SIZE, Float.MIN_VALUE, Float.MAX_VALUE);
	        printBasicTypeInfo("double", Double.TYPE, Double.BYTES, Double.SIZE, Double.MIN_VALUE, Double.MAX_VALUE);
	        printBasicTypeInfo("char", Character.TYPE, Character.BYTES, Character.SIZE, (int) Character.MIN_VALUE, (int) Character.MAX_VALUE);
	        printBasicTypeInfo("boolean", Boolean.TYPE, 1, 1, 0, 1); // boolean 特殊处理
	        
	        System.out.println("\n" + "=".repeat(60));
	        
	        // 2. 通过实际变量查看内存占用
	        System.out.println("\n实际变量内存占用示例：");
	        demonstrateMemoryUsage();
	        
	        // 3. 查看默认值
	        System.out.println("\n基本类型的默认值：");
	        showDefaultValues();
	    }
	    
	    private static void printBasicTypeInfo(String typeName, Class<?> typeClass, int bytes, int bits, 
	                                           Number min, Number max) {
	        System.out.printf("%-8s | Class: %-9s | 字节数: %d | 位数: %2d | 最小值: %-25s | 最大值: %s%n",
	                typeName,
	                typeClass.getSimpleName(),
	                bytes,
	                bits,
	                formatValue(min, typeName),
	                formatValue(max, typeName));
	    }
	    
	    private static String formatValue(Number value, String typeName) {
	        switch (typeName) {
	            case "float":
	                return String.format("%.2f", value.floatValue());
	            case "double":
	                return String.format("%.4f", value.doubleValue());
	            case "char":
	                if (value.intValue() < 32) {
	                    return "\\u" + String.format("%04x", value.intValue()) + " (控制字符)";
	                } else {
	                    return "'" + (char) value.intValue() + "' (\\u" + 
	                           String.format("%04x", value.intValue()) + ")";
	                }
	            case "boolean":
	                return "false(0) ~ true(1)";
	            default:
	                return value.toString();
	        }
	    }
	    
	    private static void demonstrateMemoryUsage() {
	        byte b = 100;
	        short s = 1000;
	        int i = 100000;
	        long l = 10000000000L;
	        float f = 3.14f;
	        double d = 3.1415926535;
	        char c = 'A';
	        boolean bool = true;
	        
	        // 通过 JOL (Java Object Layout) 风格的输出
	        System.out.println("变量声明示例：");
	        System.out.println("  byte b = " + b + ";     // 占用 1 字节");
	        System.out.println("  short s = " + s + ";    // 占用 2 字节");
	        System.out.println("  int i = " + i + ";  // 占用 4 字节");
	        System.out.println("  long l = " + l + "L; // 占用 8 字节");
	        System.out.println("  float f = " + f + "f;   // 占用 4 字节");
	        System.out.println("  double d = " + d + "; // 占用 8 字节");
	        System.out.println("  char c = '" + c + "';      // 占用 2 字节 (Unicode)");
	        System.out.println("  boolean bool = " + bool + "; // 占用 1 位 (但JVM通常用1字节)");
	    }
	    
	    private static void showDefaultValues() {
	        // 注意：这些是实例变量的默认值，局部变量必须手动初始化
	        class DefaultValues {
	            byte b;
	            short s;
	            int i;
	            long l;
	            float f;
	            double d;
	            char c;
	            boolean bool;
	        }
	        
	        DefaultValues dv = new DefaultValues();
	        System.out.println("  byte 默认值: " + dv.b);
	        System.out.println("  short 默认值: " + dv.s);
	        System.out.println("  int 默认值: " + dv.i);
	        System.out.println("  long 默认值: " + dv.l);
	        System.out.println("  float 默认值: " + dv.f);
	        System.out.println("  double 默认值: " + dv.d);
	        System.out.println("  char 默认值: " + (int) dv.c + " (Unicode: \\u" + 
	                         String.format("%04x", (int) dv.c) + ")");
	        System.out.println("  boolean 默认值: " + dv.bool);
	    }
	    
	    // 额外：查看基本类型的包装类信息
	    public static void printWrapperInfo() {
	        System.out.println("\n对应的包装类：");
	        System.out.println("基本类型 | 包装类    | 自动装箱/拆箱");
	        System.out.println("--------|-----------|--------------");
	        System.out.println("byte    | Byte      | Byte.valueOf(b) / byteValue()");
	        System.out.println("short   | Short     | Short.valueOf(s) / shortValue()");
	        System.out.println("int     | Integer   | Integer.valueOf(i) / intValue()");
	        System.out.println("long    | Long      | Long.valueOf(l) / longValue()");
	        System.out.println("float   | Float     | Float.valueOf(f) / floatValue()");
	        System.out.println("double  | Double    | Double.valueOf(d) / doubleValue()");
	        System.out.println("char    | Character | Character.valueOf(c) / charValue()");
	        System.out.println("boolean | Boolean   | Boolean.valueOf(bool) / booleanValue()");
	    }
}

public class HelloWorld { //类对应的块
	public static void main(String[] args) { //主方法对应的块
		System.out.println("abc");
	}
}

public class HelloJava{
	int i = 1;

	public void method1(int i)
	{
		System.out.println(i);
	}
	
	public void method2(final int j){
		 
	}
	
	//块1
	{
		System.out.println("执行块1！");
	}
	
	public static void main(String[] args){
		System.out.println("Hello Java");
		HelloJava $_$ = new HelloJava();
		$_$.method1(5);
		
		//块2
		{
			System.out.println("执行块2！");
		}
	}
	
	//静态块
	static {
		System.out.println("执行静态块！");
	}
}

运行结果：
执行静态块！
Hello Java
执行块1！
5
执行块2！

为什么先执行主方法中的HELLOJAVA，再到块1，再到调用的方法2，最后是块2呢？

public class ZhiXingShunXu{
	public static void main(String[] args){
		System.out.println("1");
		new D();
	}
}
class C {
	static{System.out.println("2");}
	C(){System.out.println("3");}
	{System.out.println("4");}
}
class D extends C{
	public String sd1=getSd1();
	static public String getSd(){
		System.out.println("5");
		return "sd";
	}
	static{System.out.println("6");}
	public static String sd=getSd();
	D(){System.out.println("7");}
	{System.out.println("8");}
	public String getSd1(){
		System.out.println("9");
		return "sd1";
	}
}