java 泛型学习笔记

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//首先我对泛型的理解就是可以把任何Object的子类当做类中的类型，下面是对于泛型的基本定义public class GenericT<Object> {//泛型可接受类型是 Object 的 子类private Object foo;public void setFoo(Object foo){this.foo=foo;}public Object getfoo(){return foo;}}

然后对于泛型，可以有两个类型或者更多：

public class GenericTT<T1,T2> {private T1 foo1;private T2 foo2;public T1 getFoo1() {return foo1;}public void setFoo1(T1 foo1) {this.foo1 = foo1;}public T2 getFoo2() {return foo2;}public void setFoo2(T2 foo2) {this.foo2 = foo2;}}

public class GenericTArray<T1>{//这里貌似不能直接用Tprivate T1[] fooArrayTs;public T1[] getFooArrayTs() {return fooArrayTs;}public void setFooArrayTs(T1[] fooArrayTs) {this.fooArrayTs = fooArrayTs;}}

泛型可以像类一样继承另一个泛型：

public class GenericA<T1,T2>{private T1 foo1;private T2 foo2;public T1 getFoo1() {return foo1;}public void setFoo1(T1 foo1) {this.foo1 = foo1;}public T2 getFoo2() {return foo2;}public void setFoo2(T2 foo2) {this.foo2 = foo2;}}public class GenericB<T1,T2,T3> extends GenericA<T1, T2>{private T3 foo3;public T3 getFoo3() {return foo3;}public void setFoo3(T3 foo3) {this.foo3 = foo3;}}

下面是对于泛型的实例化：

public class GenericFooDemo {public static void main(String[] argc){GenericT<Boolean> foo1 = new GenericT<Boolean>();GenericT<Integer> foo2 = new GenericT<Integer>();foo1.setFoo(new Boolean(true));Boolean b= foo1.getfoo();System.out.println(b);foo2.setFoo(new Integer(10));Integeri= foo2.getfoo();System.out.println(i);GenericTT<String, Boolean> dui=new GenericTT<>();dui.setFoo1("test");dui.setFoo2(true);System.out.println(dui.getFoo1()+"  "+dui.getFoo2());String[] strs={"hee","sadf","sdf"};GenericTArray<String> fooStrs=new GenericTArray<String>();fooStrs.setFooArrayTs(strs);for(String s:fooStrs.getFooArrayTs()){System.out.println(s);}GenericB<Integer, Boolean, String> extendsB =new GenericB<Integer, Boolean, String>();extendsB.setFoo1(12);extendsB.setFoo3("test");System.out.println(extendsB.getFoo1()+"   "+extendsB.getFoo3());}}

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