java引用传递之引用与对象修改

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package com.bobo;

public class Book {
private String bookName;

public Book(String bookName) {
this.bookName = bookName;
}

public String getBookName() {
return bookName;
}

public void setBookName(String bookName) {
this.bookName = bookName;
}
/* public static Book getInatance(String name){
return new Book(name);
}*/
}

package com.bobo;

public class TestMain {
static Book book;

public static void main(String[] args) {
book = new Book("001");
System.out.println(book.getBookName());//001
getBookChangeName(book);
System.out.println(book.getBookName());//002
getBookByNew(book);
System.out.println(book.getBookName());//002
}

//引用传递，通过引用修改指向的对象，2个引用一个实体对象，所有通过修改任何引用得到修改对象

//这个是JAVA最常用的修改对象通过引用，没有返回参数

public static void getBookChangeName(Book book) {
book.setBookName("002");
}

//此处是2个引用，但在方法里又产生新的对象付给方法里面的引用，当方法执行完就回收了，所有没有变化

//作用从新构造对象一个又返回值

public static void getBookByNew(Book book) {
book = new Book("003");
}

/*public static void getBookByInstance(Book book) {
book= Book.getInatance("004");
}*/

}

在JAVA里面一般传递对象引用：目的是修改

如果通过参数获得新对象就要返回对象引用：比如通过登录名查找用户