如果使用无界类型参数,则Java编译器将使用Object
替换类型参数。
示例
创建一个名称为:UnboundedTypesErasure.java 文件,并编写以下代码 -
package com.yiibai.demo2;
public class UnboundedTypesErasure {
public static void main(String[] args) {
Box<Integer> integerBox = new Box<Integer>();
Box<String> stringBox = new Box<String>();
integerBox.add(new Integer(1000));
stringBox.add(new String("Hello World"));
System.out.printf("Integer Value :%d\n", integerBox.get());
System.out.printf("String Value :%s\n", stringBox.get());
}
}
class Box<T> {
private T t;
public void add(T t) {
this.t = t;
}
public T get() {
return t;
}
}
在本示例中,java编译器将用Object
类替换T
,而在类型擦除之后,编译器会为以下代码生成字节码。
package com.yiibai.demo2;
public class UnboundedTypesErasure {
public static void main(String[] args) {
Box integerBox = new Box();
Box stringBox = new Box();
integerBox.add(new Integer(1000));
stringBox.add(new String("Hello World"));
System.out.printf("Integer Value :%d\n", integerBox.get());
System.out.printf("String Value :%s\n", stringBox.get());
}
}
class Box {
private Object t;
public void add(Object t) {
this.t = t;
}
public Object get() {
return t;
}
}
在这两种情况下,执行输出结果是相同的 -
Integer Value :1000
String Value :Hello World