物件屬性和陣列元素的初始預設值
阿新 • • 發佈:2019-02-06
package initialvalue.one;
public class Main {
public char charVal;
public byte byteVal;
public short shortVal;
public int intVal;
public long longVal;
public float floatVal;
public double doubleVal;
public boolean booleanVal;
public Character charObj;
public Byte byteObj;
public Short shortObj;
public Integer intObj;
public Long longObj;
public Float floatObj;
public Double doubleObj;
public Boolean booleanObj;
@Override
public String toString() {
return "Main [charVal=" + charVal + ", byteVal=" + byteVal + ", shortVal=" + shortVal + ", intVal=" + intVal
+ ", longVal=" + longVal + ", floatVal=" + floatVal + ", doubleVal=" + doubleVal + ", booleanVal="
+ booleanVal + ", charObj=" + charObj + ", byteObj=" + byteObj + ", shortObj=" + shortObj + ", intObj="
+ intObj + ", longObj=" + longObj + ", floatObj=" + floatObj + ", doubleObj=" + doubleObj
+ ", booleanObj=" + booleanObj + "]";
}
public static void main(String[] args) {
System.out.println("物件屬性初始值...");
System.out.println(new Main().toString());
System.out.println("陣列元素初始值...");
char[] charArray=new char[3];
byte[] byteArray=new byte[3];
short[] shortArray=new short[3];
int[] intArray=new int[3];
long[] longArray=new long[3];
float[] floatArray=new float[3];
double[] doubleArray=new double[3];
boolean[] booleanArray=new boolean[3];
Integer[] intObjArray=new Integer[3];
System.out.print("charArray:[");
for(char tmp: charArray){
System.out.print(tmp+",");
}
System.out.println("]");
System.out.print("byteArray:[");
for(byte tmp: byteArray){
System.out.print(tmp+",");
}
System.out.println("]");
System.out.print("shortArray:[");
for(short tmp: shortArray){
System.out.print(tmp+",");
}
System.out.println("]");
System.out.print("intArray:[");
for(int tmp: intArray){
System.out.print(tmp+",");
}
System.out.println("]");
System.out.print("longArray:[");
for(long tmp: longArray){
System.out.print(tmp+",");
}
System.out.println("]");
System.out.print("floatArray:[");
for(float tmp: floatArray){
System.out.print(tmp+",");
}
System.out.println("]");
System.out.print("doubleArray:[");
for(double tmp: doubleArray){
System.out.print(tmp+",");
}
System.out.println("]");
System.out.print("booleanArray:[");
for(boolean tmp: booleanArray){
System.out.print(tmp+",");
}
System.out.println("]");
System.out.print("intObjArray:[");
for(Integer tmp: intObjArray){
System.out.print(tmp+",");
}
System.out.println("]");
/*
* Output:
* 物件屬性初始值...
* Main [charVal= , byteVal=0, shortVal=0, intVal=0, longVal=0, floatVal=0.0, doubleVal=0.0, booleanVal=false, charObj=null, byteObj=null, shortObj=null, intObj=null, longObj=null, floatObj=null, doubleObj=null, booleanObj=null]
* 陣列元素初始值...
* charArray:[ , , ,]
* byteArray:[0,0,0,]
* shortArray:[0,0,0,]
* intArray:[0,0,0,]
* longArray:[0,0,0,]
* floatArray:[0.0,0.0,0.0,]
* doubleArray:[0.0,0.0,0.0,]
* booleanArray:[false,false,false,]
* intObjArray:[null,null,null,]
*/
}
}
注:其實可以將陣列的各元素看做陣列物件的屬性,如此物件屬性和陣列元素初始預設值就簡化為物件屬性預設值,基本型別的預設值為0(其中浮點型和雙精度浮點型預設為0.0,字元型預設為空格,布林型預設為false),引用型別的預設值為null。