Java中x=x+y与x+=y的区别，体现强制类型转换

int x+=y其实是x=(int)(x+y)

直接见下面的代码示例：

public class testCasting {
    public static void main(String arg[]) {
		int a = 10;
		int b = 20;
		double d = 12.3;
		char c = 'c';
		String s = "abc";
		//下面输出:The result of a = a + b is:30
		System.out.println("The result of a = a + b is:" + (a=a+b));   
		//下面输出:The result of a += b is:50
		System.out.println("The result of a += b is:" + (a+=b));  
		//下面输出:The result of a += d is:62(这里体现了强制类型转换为int)
		System.out.println("The result of a += d is:" + (a+=d)); 
		//下面输出:The result of a = a + d is:74(这里需要使用（int）d来进行强制转换，不然编译不过)
		System.out.println("The result of a = a + d is:"+ (a=a+(int)d));
		//下面输出:The result of a = a + d is:86.3(这里体现表达式中最大的数据类型决定最终结果的数据类型)
		System.out.println("The result of a = a + d is:"+ (a+d));    
		//下面输出:The result of a = a + c is:173(这里体现了只要类型比int，那么在运算之前，这些值会自动转换为int)
		System.out.println("The result of a = a + c is:" + (a=a+c));
		//下面输出:The result of a += c is:272
		System.out.println("The result of a += c is:" + (a+=c)); 
		//下面输出:The result of c += a is:ų(这里体现了c+=a其实是c=(char)(c+a)的实质，多了一层强制转换)
		System.out.println("The result of c += a is:" + (c+=a)); 
		//下面输出:The result of s = s + a is:abc272(下面两个涉及String的操作，体现了String的特性，表达式中出现String开头的，之后的都会转换为String进行连接)
		System.out.println("The result of s = s + a is:" + (s=s+a));
		//下面输出:The result of s += a is:abc272272
		System.out.println("The result of s += a is:" + (s+=a));
		//下面输出:The result of s = s + c is:abc272272ų
		System.out.println("The result of s = s + c is:" + (s=s+c)); 
    }
}