Example code for passing and returning objects in Java-javaTutorial-php.cn

1. The Clone() method generates an object, and the object must be assigned after using the method.

Vector v2 = (Vector)v.clone();

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2. The Clone() method is a protected type method in object. If the class you create needs to use the Clone() method, you need to rewrite it yourself and inherit the Cloneable interface.

package tweleve;import java.util.*;class MyObject implements Cloneable {int i; MyObject(int ii) { i = ii; }public Object clone() { Object object = null;try { object = super.clone(); } catch (CloneNotSupportedException e) { System.out.println("MyObject can't clone"); }return object; }public String toString() {return Integer.toString(i); } }public class LocalCopy {static MyObject g(MyObject v) { v.i++;return v; }static MyObject f(MyObject v) { v = (MyObject) v.clone(); v.i++;return v; }public static void main(String[] args) { MyObject aMyObject = new MyObject(11); MyObject bMyObject = g(aMyObject);if (aMyObject == bMyObject) System.out.println("a==b");elseSystem.out.println("a!=b"); System.out.println("a=" + aMyObject); System.out.println("b=" + bMyObject); MyObject cMyObject = new MyObject(31); MyObject dMyObject = f(cMyObject);if (cMyObject == dMyObject) System.out.println("c==d");elseSystem.out.println("c!=d"); System.out.println("c=" + cMyObject); System.out.println("d=" + dMyObject); } }

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3. If you want a class to be cloned, you need to follow the following steps: (1) Implement the Cloneable interface

lone() method

(4) Capture violations in your own clone()

4. All objects in the String class Methods that can modify String actually create and return a new String class. The original String class has not changed, including + and +=. StringBuffer is more efficient than String when operating strings.

package tweleve;import java.sql.Ref;import org.omg.CORBA.SystemException;public class Stringer {static String upcase(String s){ return s.toUpperCase(); } public static void main(String[] args){ String qString=new String("howdy"); System.out.println(qString); String qq=upcase(qString); System.out.println(qq); System.out.println(qString); } }

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