primitivewidening.java

主要是java书上的一些代码

//: PrimitiveWidening.java

//package g3ds.joop.ch3;

class PrimitiveWidening{
	public static void main(String[] args) {
		//一般情况，基本类型的扩大将自动转换，并不会存在问题
		char c = '\u0041';
		System.out.print("char->long:c=\'\\u0041\'->" );
		long l = c; // widen char to long
		System.out.println("l=0x" + Long.toHexString(l));
		
		float f = 1.23f;
		double d = f; // widen float to double
		System.out.println("float->double:f = 1.23f->d=" + d);
		
		//但要慎用从整型转换为浮点型，因为后者存在不精确性
		int big = 1234567890;
		float approx = big;
		System.out.println("int->float:(1234567890-(int)1234567890f)的结果："+(big - (int)approx));
		
		long large = 1234567890123456789L;
		double pricisionLosing = large;
		System.out.println("long->double:(1234567890123456789L-(long)1234567890123456789D)的结果："+(large - (long)pricisionLosing));
	}
}