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Student
1 package base; 2 3 import java.io.Serializable; 4 5 /** 6 * Created by robin on 2016/5/11. 7 * 8 * @author robin 9 */ 10 public class Student implements Cloneable,Serializable{ 11 12 private String stuId; 13 14 private String name; 15 16 private Integer age; 17 18 public Student(String stuId, String name, Integer age) { 19 this.stuId = stuId; 20 this.name = name; 21 this.age = age; 22 } 23 24 public Student(String stuId, String name) { 25 this.stuId = stuId; 26 this.name = name; 27 } 28 29 public String getStuId() { 30 return stuId; 31 } 32 33 public String getName() { 34 return name; 35 } 36 37 public Integer getAge() { 38 return age; 39 } 40 41 public void setStuId(String stuId) { 42 this.stuId = stuId; 43 } 44 45 public void setName(String name) { 46 this.name = name; 47 } 48 49 public void setAge(Integer age) { 50 this.age = age; 51 } 52 /** 53 * @return 创建并返回此对象的一个副本。 54 * @throws CloneNotSupportedException 55 */ 56 public Student clone() throws CloneNotSupportedException { 57 //直接调用父类的clone()方法,返回克隆副本 58 return (Student) super.clone(); 59 } 60 61 @Override 62 public String toString(){ 63 StringBuffer sb = new StringBuffer(); 64 sb.append("[stuId:"); 65 sb.append(this.stuId); 66 sb.append(",name:"); 67 sb.append(this.name); 68 sb.append(",age:"); 69 sb.append(this.age); 70 sb.append("]"); 71 return sb.toString(); 72 } 73 74 /** 75 * JAVA当中所有的类都是继承于Object这个基类的,在Object中的基类中定义了一个equals的方法,这个方法的初始行为是比较对象的内存地址。 76 * 但在一些类库当中这个方法被覆盖掉了,如String,Integer,Date在这些类当中equals有其自身的实现,而不再是比较类在堆内存中的存放地址了。 77 * 注意:对于复合数据类型之间进行equals比较,在没有覆写equals方法的情况下,他们之间的比较还是基于他们在内存中的存放位置的地址值。 78 * @param student 79 * @return 80 */ 81 public boolean equals(Student student){ 82 if(this.stuId.equals(student.getStuId()) && 83 this.age.equals(student.getAge()) && 84 this.name.equals(student.getName())){ 85 return true; 86 } 87 return false; 88 } 89 }
深度拷贝和浅层拷贝的区别代码示例
1 package base; 2 3 import java.io.*; 4 import java.util.ArrayList; 5 import java.util.List; 6 import java.util.Vector; 7 8 /** 9 * Created by robin on 2016/5/11. 10 * 11 * @author robin 12 */ 13 public class ShallowAndDeepCopy { 14 15 private static List<Student> noumenon = new Vector<Student>(); 16 17 private static void initPublicNums(){ 18 for (int i =0;i < 5;i++){ 19 Student newStu = new Student(""+i,"name:"+i,i); 20 noumenon.add(newStu); 21 } 22 } 23 24 public static void main(String args[]) throws CloneNotSupportedException { 25 initPublicNums(); 26 List<Student> quote = noumenon; 27 List<Student> shallowCopy = getPublicNumsShallow(); 28 List<Student> deepCopy = getPublicNumsDeep(); 29 List<Student> deepCommonCopy = deepCopy(noumenon); 30 System.out.println("quote List的内存地址是否相同:"+(noumenon == quote)); 31 System.out.println("shallow copy List的内存地址是否相同:"+(noumenon == shallowCopy)); 32 System.out.println("deep copy List的内存地址是否相同:" + (noumenon == deepCopy)); 33 System.out.println("deepCommon copy List的内存地址是否相同:" + (noumenon == deepCommonCopy)); 34 System.out.println("------------------shallow copy test-----------------------"); 35 for (int i=0;i<shallowCopy.size();i++){ 36 Student shallowStu = shallowCopy.get(i); 37 Student noumenonStu = noumenon.get(i); 38 System.out.println("{shallowStu detail:" + shallowStu.toString()+"}"); 39 System.out.println("{noumenonStu detail:" + noumenonStu.toString()+"}"); 40 System.out.println("{shallowStu equals noumenonStu:" + shallowStu.equals(noumenonStu)+"}"); 41 System.out.println("{shallowCopy("+i+")与noumenon("+i+")内存地址相同:"+(noumenonStu == shallowStu)+"}"); 42 System.out.println(); 43 } 44 System.out.println("------------------deep copy test-----------------------"); 45 for (int i=0;i<deepCopy.size();i++){ 46 Student deepStu = deepCopy.get(i); 47 Student noumenonStu = ShallowAndDeepCopy.noumenon.get(i); 48 System.out.println("{deepStu detail:" + deepStu.toString() + "}"); 49 System.out.println("{noumenonStu detail:" + noumenonStu.toString() + "}"); 50 System.out.println("{deepStu equals noumenonStu:" + deepStu.equals(noumenonStu) + "}"); 51 System.out.println("{deepCopy("+i+")与noumenon("+i+")内存地址相同:"+(noumenonStu == deepStu)+"}"); 52 System.out.println(); 53 } 54 System.out.println("------------------deepCommonCopy copy test-----------------------"); 55 for (int i=0;i<deepCommonCopy.size();i++){ 56 Student deepCommonStu = deepCommonCopy.get(i); 57 Student noumenonStu = ShallowAndDeepCopy.noumenon.get(i); 58 System.out.println("{deepCommonStu detail:" + deepCommonStu.toString() + "}"); 59 System.out.println("{noumenonStu detail:" + noumenonStu.toString() + "}"); 60 System.out.println("{deepCommonStu equals noumenonStu:" + deepCommonStu.equals(noumenonStu) + "}"); 61 System.out.println("{deepCommonCopy("+i+")与noumenon("+i+")内存地址相同:"+(noumenonStu == deepCommonStu)+"}"); 62 System.out.println(); 63 } 64 } 65 66 /** 67 * shallow copy:list中 元素引用 仍然是相同的 68 * @return 69 */ 70 private static List<Student> getPublicNumsShallow(){ 71 List<Student> clone = new ArrayList<Student>(noumenon); 72 return clone; 73 } 74 75 /** 76 * deep copy:list中 引用元素 地址是不同的 77 * @return 78 * @throws CloneNotSupportedException 79 */ 80 private static List<Student> getPublicNumsDeep() throws CloneNotSupportedException { 81 List<Student> clone = new ArrayList<Student>(); 82 for (int i=0;i< noumenon.size();i++){ 83 clone.add(noumenon.get(i).clone()); 84 } 85 return clone; 86 } 87 88 /** 89 * 深度复制 这种实现的深度复制,是不需要被复制的元素实现clone方法的 但JDK版本要求:1.7及以上 90 * @param src 这个是同事完成 非本人开发 91 * @return 92 */ 93 private static List deepCopy(List src) { 94 List dest = null; 95 ByteArrayInputStream byteIn = null; 96 ObjectInputStream in = null; 97 try (ByteArrayOutputStream byteOut = new ByteArrayOutputStream(); 98 ObjectOutputStream out = new ObjectOutputStream(byteOut)) { 99 out.writeObject(src); 100 byteIn = new ByteArrayInputStream(byteOut.toByteArray()); 101 in = new ObjectInputStream(byteIn); 102 dest = (List) in.readObject(); 103 } catch (IOException | ClassNotFoundException e) { 104 e.printStackTrace(); 105 } finally { 106 try { 107 if (in != null) { 108 in.close(); 109 } 110 if (byteIn != null) { 111 byteIn.close(); 112 } 113 } catch (IOException e) { 114 e.printStackTrace(); 115 } 116 } 117 return dest; 118 } 119 120 121 }
执行结果:
1 quote List的内存地址是否相同:true 2 shallow copy List的内存地址是否相同:false 3 deep copy List的内存地址是否相同:false 4 deepCommon copy List的内存地址是否相同:false 5 ------------------shallow copy test----------------------- 6 {shallowStu detail:[stuId:0,name:name:0,age:0]} 7 {noumenonStu detail:[stuId:0,name:name:0,age:0]} 8 {shallowStu equals noumenonStu:true} 9 {shallowCopy(0)与noumenon(0)内存地址相同:true} 10 11 {shallowStu detail:[stuId:1,name:name:1,age:1]} 12 {noumenonStu detail:[stuId:1,name:name:1,age:1]} 13 {shallowStu equals noumenonStu:true} 14 {shallowCopy(1)与noumenon(1)内存地址相同:true} 15 16 {shallowStu detail:[stuId:2,name:name:2,age:2]} 17 {noumenonStu detail:[stuId:2,name:name:2,age:2]} 18 {shallowStu equals noumenonStu:true} 19 {shallowCopy(2)与noumenon(2)内存地址相同:true} 20 21 {shallowStu detail:[stuId:3,name:name:3,age:3]} 22 {noumenonStu detail:[stuId:3,name:name:3,age:3]} 23 {shallowStu equals noumenonStu:true} 24 {shallowCopy(3)与noumenon(3)内存地址相同:true} 25 26 {shallowStu detail:[stuId:4,name:name:4,age:4]} 27 {noumenonStu detail:[stuId:4,name:name:4,age:4]} 28 {shallowStu equals noumenonStu:true} 29 {shallowCopy(4)与noumenon(4)内存地址相同:true} 30 31 ------------------deep copy test----------------------- 32 {deepStu detail:[stuId:0,name:name:0,age:0]} 33 {noumenonStu detail:[stuId:0,name:name:0,age:0]} 34 {deepStu equals noumenonStu:true} 35 {deepCopy(0)与noumenon(0)内存地址相同:false} 36 37 {deepStu detail:[stuId:1,name:name:1,age:1]} 38 {noumenonStu detail:[stuId:1,name:name:1,age:1]} 39 {deepStu equals noumenonStu:true} 40 {deepCopy(1)与noumenon(1)内存地址相同:false} 41 42 {deepStu detail:[stuId:2,name:name:2,age:2]} 43 {noumenonStu detail:[stuId:2,name:name:2,age:2]} 44 {deepStu equals noumenonStu:true} 45 {deepCopy(2)与noumenon(2)内存地址相同:false} 46 47 {deepStu detail:[stuId:3,name:name:3,age:3]} 48 {noumenonStu detail:[stuId:3,name:name:3,age:3]} 49 {deepStu equals noumenonStu:true} 50 {deepCopy(3)与noumenon(3)内存地址相同:false} 51 52 {deepStu detail:[stuId:4,name:name:4,age:4]} 53 {noumenonStu detail:[stuId:4,name:name:4,age:4]} 54 {deepStu equals noumenonStu:true} 55 {deepCopy(4)与noumenon(4)内存地址相同:false} 56 57 ------------------deepCommonCopy copy test----------------------- 58 {deepCommonStu detail:[stuId:0,name:name:0,age:0]} 59 {noumenonStu detail:[stuId:0,name:name:0,age:0]} 60 {deepCommonStu equals noumenonStu:true} 61 {deepCommonCopy(0)与noumenon(0)内存地址相同:false} 62 63 {deepCommonStu detail:[stuId:1,name:name:1,age:1]} 64 {noumenonStu detail:[stuId:1,name:name:1,age:1]} 65 {deepCommonStu equals noumenonStu:true} 66 {deepCommonCopy(1)与noumenon(1)内存地址相同:false} 67 68 {deepCommonStu detail:[stuId:2,name:name:2,age:2]} 69 {noumenonStu detail:[stuId:2,name:name:2,age:2]} 70 {deepCommonStu equals noumenonStu:true} 71 {deepCommonCopy(2)与noumenon(2)内存地址相同:false} 72 73 {deepCommonStu detail:[stuId:3,name:name:3,age:3]} 74 {noumenonStu detail:[stuId:3,name:name:3,age:3]} 75 {deepCommonStu equals noumenonStu:true} 76 {deepCommonCopy(3)与noumenon(3)内存地址相同:false} 77 78 {deepCommonStu detail:[stuId:4,name:name:4,age:4]} 79 {noumenonStu detail:[stuId:4,name:name:4,age:4]} 80 {deepCommonStu equals noumenonStu:true} 81 {deepCommonCopy(4)与noumenon(4)内存地址相同:false}