java中修改函数的返回值也可能会影响实参(引用传递和值传递)

快来打我* 2022-11-10 05:43 158阅读 0赞

**值传递**(实参的**值**被拷贝了一份传递给形参)

**引用传递**(实参的**内存地址**被拷贝了一份传递给形参)

**案例1**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70][]

public double[] calculate(double[] parameter) {
    		System.out.println("*************这是函数内部*************");
    		System.out.print("形参内存地址" + System.identityHashCode(parameter) + " ");
    		System.out.println("形参数据" + "[" + parameter[0] + ", " + parameter[1] + ", " + parameter[2] + "]");
    		//使用了new关键字，说明变量box指向了新的内存地址
    		double[] box = new double[parameter.length];
    		for (int index = 0; index < parameter.length; index++) {
    			box[index] = parameter[index];
    		}
    		System.out.println("..................box修改前..................");
    		System.out.println("box内存地址" + System.identityHashCode(box));
    		System.out.println("box数组的值为" + "[" + box[0] + ", " + box[1] + ", " + box[2] + "]");
    		box[0] = 88.88;
    		System.out.println("..................box修改后..................");
    		System.out.println("box内存地址" + System.identityHashCode(box));
    		System.out.println("box数组的值为" + "[" + box[0] + ", " + box[1] + ", " + box[2] + "]");
    		System.out.print("形参内存地址" + System.identityHashCode(parameter) + " ");
    		System.out.println("形参数据" + "[" + parameter[0] + ", " + parameter[1] + ", " + parameter[2] + "]");
    		System.out.println("*************这是函数内部*************");
    		return box;
    	}
    
    public static void main(String[] args) {
    		User user = new User();
    		
    		double[] numbers = {5.7, 3.9, 22.78};
    		System.out.print("调用函数前，实参内存地址" + System.identityHashCode(numbers) + " ");
    		System.out.println("调用函数前，实参数据" + "[" + numbers[0] + ", " + numbers[1] + ", " + numbers[2] + "]\n");
    		double[] res2 = user.calculate(numbers);
    		System.out.println("\n调用函数后，函数返回值内存地址" + System.identityHashCode(res2));
    		System.out.println("调用函数后，实参数据" + "[" + numbers[0] + ", " + numbers[1] + ", " + numbers[2] + "]");
    		
    		
    	}

**运行结果如下：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 1][]

**案例2**

函数的返回值是实参的内存地址

public static void main(String[] args) {
    		Test2 test2 = new Test2();
    
    		int[] socre = { 66, 88, 99 };
    		System.out.println(socre[0]); // 66
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		int[] result = test2.t1(socre);
    
    		System.out.println(socre[0]); // 66
    		System.out.println(result[0]); // 66
            //修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result[0] = 27;
    
    		System.out.println(socre[0]); // 27
    		System.out.println(result[0]); // 27
    		
    
    	}
    
    	public int[] t1(int[] p) {
    		return p;// 这里返回的p,其实是实参的内存地址
    	}

**运行结果如下：**

![20210316222600228.png][]

**案例3**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 2][]

public static void main(String[] args) {
    		Test2 test2 = new Test2();
    
    		int[] socre = { 66, 88, 99 };
    		System.out.println(socre[0]); // 66
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		int[] result = test2.t2(socre);
    
    		System.out.println(socre[0]); // 66
    		System.out.println(result[0]); // 66
    		//修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result[0] = 27;
    
    		System.out.println(socre[0]); // 27
    		System.out.println(result[0]); // 27
    		
    
    	}
    
    	public int[] t2(int[] p) {
    		int[] a = p;
    		return a;
    	}

**运行结果如下：**

![20210316222600228.png][]

**案例4**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 3][]

public static void main(String[] args) {
    		Test2 test2 = new Test2();
    
    		int[] socre = { 66, 88, 99 };
    		System.out.println(socre[0]); // 66
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		int[] result = test2.t3(socre);
    
    		System.out.println(socre[0]); // 23
    		System.out.println(result[0]); // 23
    		//修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result[0] = 27;
    
    		System.out.println(socre[0]); // 27
    		System.out.println(result[0]); // 27
    		
    
    	}
    
    	public int[] t3(int[] p) {
    		p[0] = 23;
    		int[] a = p;
    		return a;
    	}

**运行结果如下：**

![20210318011325895.png][]

**案例5**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 4][]

public static void main(String[] args) {
    		Test2 test2 = new Test2();
    
    		int[] socre = { 66, 88, 99 };
    		System.out.println(socre[0]); //
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		int[] result = test2.t4(socre);
    
    		System.out.println(socre[0]); //
    		System.out.println(result[0]); //
    		//修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result[0] = 27;
    
    		System.out.println(socre[0]); //
    		System.out.println(result[0]); //
    		
    
    	}
    
    	public int[] t4(int[] p) {
    		int[] a = null;
    		for (int i = 0; i < p.length; i++) {
    			a[i] = p[i];
    		}
    		return a;
    	}

**运行结果如下：**

![20210318012034150.png][]

**案例6**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 5][]

public static void main(String[] args) {
    		Test2 test2 = new Test2();
    
    		int[] socre = { 66, 88, 99 };
    		System.out.println(socre[0]); //
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		int[] result = test2.t5(socre);
    
    		System.out.println(socre[0]); //
    		System.out.println(result[0]); //
    		//修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result[0] = 27;
    
    		System.out.println(socre[0]); //
    		System.out.println(result[0]); //
    	}
    
    	public int[] t5(int[] p) {
    		int[] a = null;
    		p[0] = 78;
    		for (int i = 0; i < p.length; i++) {
    			a[i] = p[i];
    		}
    		return a;
    	}

**运行结果如下：**

![20210318012549141.png][]

**案例7**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 6][]

public static void main(String[] args) {
    		Test2 test2 = new Test2();
    
    		int[] socre = { 66, 88, 99 };
    		System.out.println(socre[0]); //66
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		int[] result = test2.t6(socre);
    
    		System.out.println(socre[0]); //328
    		System.out.println(result[0]); //66
    		//修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result[0] = 27;
    
    		System.out.println(socre[0]); //328
    		System.out.println(result[0]); //27
    	}
    
    	public int[] t6(int[] p) {
    		int[] a = new int[p.length];
    		for (int i = 0; i < p.length; i++) {
    			a[i] = p[i];
    		}
    		p[0] = 328;
    		return a;
    	}

**运行结果如下：**

![20210318014134563.png][]

**案例8**

![20210318020038668.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 7][]

package com.test;
    
    public class User {
    	String hometown = "江西省赣州市于都县";
    	int age = 26;
    
    	public static void main(String[] args) {
    		
    	}
    }

package com.test;
    
    public class Test2 {
    	public static void main(String[] args) {
    		Test2 test2 = new Test2();
    		
    		User user = new User();
    
    		System.out.println(user.hometown + "," + user.age); //江西省赣州市于都县,26
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		User result = test2.t7(user);
    
    		System.out.println(user.hometown + "," + user.age); //江西省赣州市于都县,26
    		System.out.println(result.hometown + "," + result.age); //江西省赣州市于都县,26
    		//修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result.hometown = "赣州于都县";
    
    		System.out.println(user.hometown); //赣州于都县
    		System.out.println(result.hometown); //赣州于都县
    	}
    
    	public User t7(User u) {
    		return u;
    	}
    
    }

**运行结果如下：**

![20210318020301141.png][]

**案例9**

![20210318020038668.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 8][]

package com.test;
    
    public class User {
    	String hometown = "江西省赣州市于都县";
    	int age = 26;
    
    	public static void main(String[] args) {
    		
    	}
    }

package com.test;
    
    public class Test2 {
    	public static void main(String[] args) {
    		Test2 test2 = new Test2();
    		
    		User user = new User();
    
    		System.out.println(user.hometown + "," + user.age); //江西省赣州市于都县,26
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		User result = test2.t8(user);
    
    		System.out.println(user.hometown + "," + user.age); //我老家在江西于都县哦...,26
    		System.out.println(result.hometown + "," + result.age); //我老家在江西于都县哦...,26
    		//修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result.hometown = "赣州于都县";
    
    		System.out.println(user.hometown); //赣州于都县
    		System.out.println(result.hometown); //赣州于都县
    	}
    
    	public User t8(User u) {
    		u.hometown = "我老家在江西于都县哦...";
    		return u;
    	}
    
    }

**运行结果如下：**

![2021031802073895.png][]

**案例10**

![20210318020038668.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 9][]

package com.test;
    
    public class User {
    	String hometown = "江西省赣州市于都县";
    	int age = 26;
    
    	public static void main(String[] args) {
    		
    	}
    }

package com.test;
    
    public class Test2 {
    	public static void main(String[] args) {
    		Test2 test2 = new Test2();
    		
    		User user = new User();
    
    		System.out.println(user.hometown + "," + user.age); //江西省赣州市于都县,26
    
    		// 用变量result来接收函数的返回值(函数的返回值其实是实参的地址)
    		User result = test2.t9(user);
    
    		System.out.println(user.hometown + "," + user.age); //江西省赣州市于都县,26
    		System.out.println(result.hometown + "," + result.age); //江西省赣州市于都县,26
    		//修改函数的返回值，会影响到实参，说明函数的返回值和实参指向的是同一个内存地址
    		result.hometown = "赣州于都县";
    
    		System.out.println(user.hometown); //赣州于都县
    		System.out.println(result.hometown); //赣州于都县
    	}
    
    	public User t9(User u) {
    		User u2 = u;
    		return u2;
    	}
    }

**运行结果如下：**

![20210318021140496.png][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70]: /images/20221023/66bf93ef149b474fbf145f2663e5072a.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 1]: /images/20221023/c872316aaa284f4b8a8ced5de0a1fede.png
[20210316222600228.png]: /images/20221023/6c93dc933543464e99db1a6549beef1d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 2]: /images/20221023/b4c0a69605b24823bdbc96e88c381eb7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 3]: /images/20221023/a25b2244112d416ab652e4615dcd6d14.png
[20210318011325895.png]: /images/20221023/c79c5516f33c4344873207ec4535fddb.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 4]: /images/20221023/561c4f7e309b4897b654e2d1c941013a.png
[20210318012034150.png]: /images/20221023/5e14cf5bc96b4b609f4c18a342f94638.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 5]: /images/20221023/e15803a804ca4b9095598f1d5c42fd69.png
[20210318012549141.png]: /images/20221023/a82b08f9f9b44188a95e2a36860f2c9c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 6]: /images/20221023/dc4f2cd40e544a2492b157ce9e5066ef.png
[20210318014134563.png]: /images/20221023/4abd8b2c0dd54e06a02f8cdb9a52e8bc.png
[20210318020038668.png]: /images/20221023/7cda870e8e1d4b37bc072a04d07b5d8d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 7]: /images/20221023/51d1b44356fe48f799725cc4eb15657f.png
[20210318020301141.png]: /images/20221023/5a5dfa99f2ff4c96b82867197aa3b277.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 8]: /images/20221023/c737f16f815c4b9bb4fc6f5556f6448a.png
[2021031802073895.png]: /images/20221023/6f411f4649254b0ab4d002e4c1713e0e.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 9]: /images/20221023/03d4233288df44eebf5e603f801e34b2.png
[20210318021140496.png]: /images/20221023/252c49f19f874069a34ae9da8b171090.png