Java 基础一些代码练习笔记（ GenericFoo<T> 泛型）

最新推荐文章于 2021-02-28 05:13:14 发布

totome911

最新推荐文章于 2021-02-28 05:13:14 发布

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分类专栏： Java基础笔记文章标签：代码练习 java string integer null class

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本文详细介绍了Java中泛型的应用，并通过实例展示了如何使用泛型类和集合类，包括设置和获取对象、数组操作及集合类的使用。

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package com.lee2;

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>();
		
		foo1.setFoo(new Boolean(false));
		foo2.setFoo(new Integer(3));
		
		Boolean b = foo1.getFoo();
		Integer i = foo2.getFoo();
		
		System.out.println(b);
		System.out.println(i);
		
	}
}

package com.lee2;

public class Generic2<T>
{
	private T [] fooArray;

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

	public void setFooArray(T[] fooArray)
	{
		this.fooArray = fooArray;
	}
	
	public static void main(String[] args)
	{
		Generic2<String> foo = new Generic2<String>();
		
		String [] str1 = {"hello", "world", "welcome"};
		String [] str2 = null;
		
		 foo.setFooArray(str1);
		 str2 = foo.getFooArray();
		 
		 for(int i = 0; i < str2.length; i++)
		 {
			 System.out.println(str2[i]);
		 }
		
		
	}
}

package com.lee2;

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>();
		
		foo1.setFoo(new Boolean(false));
		foo2.setFoo(new Integer(3));
		
		Boolean b = foo1.getFoo();
		Integer i = foo2.getFoo();
		
		System.out.println(b);
		System.out.println(i);
		
	}
}

package com.lee2;

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);
		}
		
		System.out.println("------------------");
		
		Set<People> set2 = new HashSet<People>();
		
		set2.add(new People("zhangsan",20 , "Beijing"));
		set2.add(new People("lisi",30 ,"shanghai"));
		set2.add(new People("wangwu", 40 ,"tianjin"));
		
		for(Iterator<People> iter = set2.iterator(); iter.hasNext();)
		{
			People people = iter.next();
			
			String name = people.getName();
			int age = people.getAge();
			String address = people.getAddress();
			
			System.out.println(name + "," + age + "," + address);
		}
	}
}

class People
{
	public String getName()
	{
		return name;
	}

	public int getAge()
	{
		return age;
	}

	public String getAddress()
	{
		return address;
	}

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

	@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;
	}
	
}