java参数传递-优快云博客

本文通过三个实例详细解析了Java中基本类型和引用类型参数传递的特点。对于基本类型的参数，传递的是值的拷贝，因此在方法内的修改不会影响原始变量。而对于引用类型的参数，虽然传递的是对象引用的拷贝，但可以通过该引用改变对象的状态。

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java语言中参数传递是常见的问题之一，通过阅读如下测试代码，可以看看你是否真的了解java常见的参数传递的规则。

public class TestChangeParamInt {

	public static void main(String[] args) {
		int n = 3;
		System.out.println("Before change : " + n);
		
		changeData(n);
		System.out.println("After changeData(n) : " + n);
	}

	public static void changeData(int n) {
		n = 10;
	}

}

public class TestChangeParamObj1 {	

	public static void changeData(StringBuffer strBuffer) {
		strBuffer.append("World!");
	}

	public static void main(String[] args) {
		StringBuffer strBuffer = new StringBuffer("Hello ");
		System.out.println("Before change : " + strBuffer);

		changeData(strBuffer);
		System.out.println("After changeData(n) : " + strBuffer);
	}
}


public class TestChangeParamObj2 {

	public static void main(String[] args) {
		StringBuffer strBuffer = new StringBuffer("main ");
		System.out.println("Before change = " + strBuffer);
		
		changeData(strBuffer);
		System.out.println("After changeData(n) = " + strBuffer);
	}

	public static void changeData(StringBuffer strBuffer) {
		strBuffer = new StringBuffer("Change ");
		strBuffer.append("World!");
	}

}

public class TestChangeParamObj3 {

	public static void main(String[] args) {
		StringBuffer strBuffer = new StringBuffer("Hello ");
		System.out.println("Before change = " + strBuffer);

		changeData(strBuffer);
		System.out.println("After changeData(n) = " + strBuffer);
	}
	
	public static void changeData(StringBuffer strBuffer) {
		StringBuffer sb2 = new StringBuffer("change ");
		strBuffer = sb2;
		sb2.append("World!");
		System.out.println("In changeData(n) = " + sb2);
	}

}