泛型基础(一)

GenericFoo

package org.wp.activity;

public class GenericFoo<T> {
	private T foo;

	public T getFoo() {
		return foo;
	}

	public void setFoo(T foo) {
		this.foo = foo;
	}

	public static void main(String args[]) {
		GenericFoo<Boolean> foo1 = new GenericFoo<Boolean>();
		GenericFoo<Integer> foo2 = new GenericFoo<Integer>();
		GenericFoo foo3 = new GenericFoo();

		foo1.setFoo(new Boolean(false));
		foo2.setFoo(new Integer(3));
		foo3.setFoo("hello");

		Boolean b = foo1.getFoo();
		Integer i = foo2.getFoo();
		String s = (String) foo3.getFoo();

		System.out.println(b);
		System.out.println(i);
		System.out.println(s);
	}
}

 

Generic

package org.wp.activity;

public class Generic<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 static void main(String args[]) {
		Generic<Integer, Boolean> foo = new Generic<Integer, Boolean>();
		foo.setFoo1(new Integer(-20));
		foo.setFoo2(new Boolean(false));

		System.out.println(foo.getFoo1());
		System.out.println(foo.getFoo2());
	}
}

 

GenericArray

package org.wp.activity;

public class GenericArray<T> {
	private T[] fooArray;

	public T[] getFooArray() {
		return fooArray;
	}

	public void setFooArray(T[] fooArray) {
		this.fooArray = fooArray;
	}

	public static void main(String args[]) {
		GenericArray<String> foo = new GenericArray<String>();
		String[] str1 = { "hello", "world", "welcome" };
		String[] str2 = null;

		foo.setFooArray(str1);
		str2 = foo.getFooArray();

		for (String s : str2) {
			System.out.println(s);
		}
	}
}

 

SimpleCollection

package org.wp.activity;

public class SimpleCollection<T> {
	private T[] objArr = null;
	private int index = 0;

	public SimpleCollection() {
		objArr = (T[]) new Object[10];
	}

	public SimpleCollection(int capacity) {
		objArr = (T[]) new Object[capacity];
	}

	public void add(T t) {
		objArr[index++] = t;
	}

	public T get(int i) {
		return objArr[i];
	}

	public int getLength() {
		return this.index;
	}

	public static void main(String args[]) {
		SimpleCollection<Integer> c = new SimpleCollection<Integer>();
		for (int i = 0; i < 10; i++) {
			c.add(new Integer(i));
		}

		for (int i = 0; i < c.getLength(); i++) {
			Integer j = c.get(i);
			System.out.println(j);
		}
	}
}

 

WrapperFoo

package org.wp.activity;

public class WrapperFoo<T> {
	private GenericFo<T> foo;

	public GenericFo<T> getFoo() {
		return foo;
	}

	public void setFoo(GenericFo<T> foo) {
		this.foo = foo;
	}

	public static void main(String args[]) {
		GenericFo<Integer> foo = new GenericFo<Integer>();
		foo.setFoo(new Integer(-10));

		WrapperFoo<Integer> wrapper = new WrapperFoo<Integer>();
		wrapper.setFoo(foo);

		GenericFo<Integer> gf = wrapper.getFoo();
		System.out.println(gf.getFoo());
	}
}

class GenericFo<T> {
	private T foo;

	public T getFoo() {
		return foo;
	}

	public void setFoo(T foo) {
		this.foo = foo;
	}
}

 

ArrayListTest

package org.wp.activity;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class ArrayListTest {
	public static void main(String args[]) {
		List<String> list = new ArrayList<String>();
		list.add("a");
		list.add("b");
		list.add("c");
		list.add("d");
		list.add("e");

		for (int i = 0; i < list.size(); i++) {
			String value = list.get(i);
			System.out.println(value);
		}

		for (Iterator<String> iter = list.iterator(); iter.hasNext();) {
			String value = iter.next();
			System.out.println(value);
		}
	}
}

 

SetTest

package org.wp.activity;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class SetTest {
	public static void main(String args[]) {
		Set<String> set = new HashSet<String>();
		set.add("aa");
		set.add("bb");
		set.add("cc");

		for (Iterator<String> iter = set.iterator(); iter.hasNext();) {
			String value = iter.next();
			System.out.println(value);
		}

		Set<People> setpeo = new HashSet<People>();
		setpeo.add(new People("zhangsan", 20, "beijing"));
		setpeo.add(new People("lisi", 30, "shanghai"));
		setpeo.add(new People("wangwu", 40, "tianjin"));

		for (Iterator<People> iter = setpeo.iterator(); iter.hasNext();) {
			People people = iter.next();

			String name = people.getName();
			int age = people.getAge();
			String address = people.getAddress();

			System.out.println("People [name=" + name + ", address=" + address + ", age=" + age + "]");
		}
	}
}

class People {
	private String name;
	private int age;
	private String address;

	public People(String name, int age, String address) {
		this.name = name;
		this.age = age;
		this.address = address;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((address == null) ? 0 : address.hashCode());
		result = prime * result + age;
		result = prime * result + ((name == null) ? 0 : name.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		People other = (People) obj;
		if (address == null) {
			if (other.address != null)
				return false;
		} else if (!address.equals(other.address))
			return false;
		if (age != other.age)
			return false;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		return true;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}
}

 

MapTest

package org.wp.activity;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class MapTest {
	public static void main(String args[]) {
		Map<String, String> map = new HashMap<String, String>();
		map.put("a", "aa");
		map.put("b", "bb");
		map.put("c", "cc");
		map.put("d", "dd");
		map.put("e", "ee");

		Set<String> set = map.keySet();
		for (Iterator<String> iter = set.iterator(); iter.hasNext();) {
			String key = iter.next();
			String value = map.get(key);
			System.out.println(value);
		}

		System.out.println("=====================================");

		Set<Map.Entry<String, String>> entrySet = map.entrySet();
		for (Iterator<Map.Entry<String, String>> iter = entrySet.iterator(); iter.hasNext();) {
			Map.Entry<String, String> entry = iter.next();

			String key = entry.getKey();
			String value = entry.getValue();

			System.out.println("key:" + key + ",value:" + value);
		}
	}
}