java中方法的参数是值传递。基本类型的数据无法实现赋值

想写一个交换的方法

//exchange
public static void swap(double a,double b){
	double temp;
	temp=b;
	b=a;
	a=temp;
	System.out.printf("in swap function,after swap,a is %.2f,b is %.2f\n",a,b);
}

但是查阅了资料，这个方法执行后，只会改变方法体里的变量值。方法体之外的变量还是原来的样子。

//exchange basic dataType
double a=1.0;
double b=2.0;
Tools.swap(a,b);
System.out.printf("a is %.2f,b is %.2f\n",a,b);

两种解决方案：
1.不用方法，每次交换都现写

double temp;
temp=b;
b=a;
a=temp;

2.将基本数据类型包装到引用数据类型里

class DataSwap{
		double value;
}

//exchange basic dataType
		double a=1.0;
		double b=2.0;
		Tools.swap(a,b);
		System.out.printf("a is %.2f,b is %.2f\n",a,b);

		//exchange reference dataType
		DataSwap dataObj1=new DataSwap();
		DataSwap dataObj2=new DataSwap();
		dataObj1.value=1;
		dataObj2.value=2;
		Tools.swap(dataObj1,dataObj2);
		System.out.printf("a is %.2f,b is %.2f\n",dataObj1.value,dataObj2.value);

//exchange
public static void swap(DataSwap ds1,DataSwap ds2){
	double temp;
	temp=ds2.value;
	ds2.value=ds1.value;
	ds1.value=temp;
	System.out.printf("in swap function,after swap,a is %.2f,b is %.2f\n",ds1.value,ds2.value);
}

应该可以用自动装箱拆箱来解决