int 和Integer创建对象在内存中的初始值不同

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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));    }}

运行结果为：

[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]

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