绑定类型擦除(Bound Types Erasure)
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小牛编辑
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2023-12-01
如果使用有界类型参数,Java Compiler将使用其绑定替换泛型类型中的类型参数。
例子 (Example)
package cn.xnip;
public class GenericsTester {
public static void main(String[] args) {
Box<Integer> integerBox = new Box<Integer>();
Box<Double> doubleBox = new Box<Double>();
integerBox.add(new Integer(10));
doubleBox.add(new Double(10.0));
System.out.printf("Integer Value :%d\n", integerBox.get());
System.out.printf("Double Value :%s\n", doubleBox.get());
}
}
class Box<T extends Number> {
private T t;
public void add(T t) {
this.t = t;
}
public T get() {
return t;
}
}
在这种情况下,java编译器将用Number类替换T,在类型擦除之后,编译器将为以下代码生成字节码。
package cn.xnip;
public class GenericsTester {
public static void main(String[] args) {
Box integerBox = new Box();
Box doubleBox = new Box();
integerBox.add(new Integer(10));
doubleBox.add(new Double(10.0));
System.out.printf("Integer Value :%d\n", integerBox.get());
System.out.printf("Double Value :%s\n", doubleBox.get());
}
}
class Box {
private Number t;
public void add(Number t) {
this.t = t;
}
public Number get() {
return t;
}
}
在这两种情况下,结果都是一样的 -
输出 (Output)
Integer Value :10
Double Value :10.0