170537-Generic

OneCodeOneTime · OneCodeOneTime · commit e9b0698f2a7f · 2017-05-27T15:35:50.000+08:00
diff --git a/src/btp/oneP/GenericErase.java b/src/btp/oneP/GenericErase.java
@@ -0,0 +1,22 @@
+package btp.oneP;
+
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+
+public class GenericErase {
+
+	public static void main(String[] args) {
+		ArrayList<String> sl = new ArrayList<String>();
+		sl.add("Magic");
+		Class<? extends ArrayList> clazz = sl.getClass();
+		try{
+			Method method = clazz.getMethod("add", Object.class);
+			method.invoke(sl, 1);
+			System.out.println(sl);
+			//out:[Magic, 1]
+		}catch(Exception e){
+			e.printStackTrace();
+		}
+	}
+
+}
diff --git a/src/btp/oneP/GenericEvaluate.java b/src/btp/oneP/GenericEvaluate.java
@@ -0,0 +1,29 @@
+package btp.oneP;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+public class GenericEvaluate {
+
+	public static void main(String[] args) {
+		Collection<Pair<String,Long>> c1 = new ArrayList<Pair<String,Long>>();
+		Collection<Pair<String,Long>> c2 = c1;
+		//Collection<Pair<String,?>> c3 = c1;
+		Collection<? extends Pair<String,?>> c4 = c1;
+		
+		Collection<SubTypeOfPair<String,Long>> c5 = new ArrayList<SubTypeOfPair<String,Long>>();
+		//Collection<Pair<String,Long>> c6 = c5;
+		Collection<SubTypeOfPair<String,Long>> c7 = c5;
+		//Collection<Pair<String,?>> c8 = c5;
+		Collection<? extends Pair<String,?>> c9 = c5;
+	}
+
+}
+
+class Pair<K,V>{
+	
+}
+
+class SubTypeOfPair<K,V> extends Pair<K, V>{
+	
+}
diff --git a/src/btp/oneP/ListCopy.java b/src/btp/oneP/ListCopy.java
@@ -0,0 +1,24 @@
+package btp.oneP;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class ListCopy {
+	
+	public static <T> void copy(List<? extends T> src,List<? super T> dest){
+		for(T t:src){
+			dest.add(t);
+		}
+	}
+	
+	public static void main(String[] args) {
+		List<String> sList = new ArrayList<String>(Arrays.<String>asList(new String[]{"hehe","xixi","caca"}));
+		List<Object> oList = new ArrayList<Object>();
+		copy(sList,oList);
+		for(Object o:oList){
+			System.out.println(o);
+		}
+	}
+
+}
