int 和Integer创建对象在内存中的初始值不同

int 和Integer创建对象在内存中的初始值不同：

package deleteArrary;

import java.util.Arrays;

/**
 * Created by Administrator on 2015/11/23 0023.
 */
public class deffIntToInteger {
    public static void main(String[] args) {
        int []a=new int[5];
        Integer []b=new Integer[5];
        System.out.println(Arrays.toString(a));
        System.out.println(Arrays.toString(b));
    }
}

[0, 0, 0, 0, 0]
[null, null, null, null, null]


Process finished with exit code 0

下面是个类型的对比：

package deleteArrary;

import java.util.Arrays;

/**
 * Created by Administrator on 2015/11/23 0023.
 */
public class deffIntToInteger {
    public static void main(String[] args) {
        int []a=new int[5];
        Integer []b=new Integer[5];

        String []strings=new String[5];

        Character []characters=new Character[5];
        char []c=new char[5];

        byte []b1=new byte[5];

        double []d=new double[4];
        Double []doubles=new Double[5];

        boolean []booleans=new boolean[5];

        short []shorts=new short[5];
        float []f=new float[5];
        Float []floats=new Float[5];


        System.out.println(Arrays.toString(a));
        System.out.println(Arrays.toString(b));
        System.out.println(Arrays.toString(strings));
        System.out.println(Arrays.toString(characters));
        System.out.println(Arrays.toString(c));
        System.out.println(Arrays.toString(b1));
        System.out.println(Arrays.toString(d));
        System.out.println(Arrays.toString(doubles));
        System.out.println(Arrays.toString(booleans));
        System.out.println(Arrays.toString(shorts));
        System.out.println(Arrays.toString(f));
        System.out.println(Arrays.toString(floats));

    }
}

运行结果：

[0, 0, 0, 0, 0]
[null, null, null, null, null]
[null, null, null, null, null]
[null, null, null, null, null]
[ ,  ,  ,  ,  ]
[0, 0, 0, 0, 0]
[0.0, 0.0, 0.0, 0.0]
[null, null, null, null, null]
[false, false, false, false, false]
[0, 0, 0, 0, 0]
[0.0, 0.0, 0.0, 0.0, 0.0]
[null, null, null, null, null]