初步结论:泛型类型转换不靠谱;
源码:
package com.srie.testjava; public class TestClassDefine4<T> { public static void main(String[] args) { TestClassDefine4<String> t4 = new TestClassDefine4<String>(); String cast = t4.badCast(1); System.out.println(cast); } T badCast(Integer i) { return (T) i; // 此处有warning } }
反编译:
package com.srie.testjava; import java.io.PrintStream; public class TestClassDefine4<T> { public static void main(String[] args) { TestClassDefine4 t4 = new TestClassDefine4(); String cast = (String)t4.badCast(Integer.valueOf(1)); System.out.println(cast); } T badCast(Integer i) { return i; } }
运行异常:
Exception in thread "main" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
at com.srie.testjava.TestClassDefine4.main(TestClassDefine4.java:7)