Java基礎之陣列

定義:

dataType[]arrayName // 首選的方法

dataType arrayName[] // 效果相同，但不是首選方法

dataType為Java中的任意資料型別，包括基本型別和組合型別，arrayName為陣列名，必須是一個合法的識別符號，[ ] 指明該變數是一個陣列型別變數,arraySize為陣列的初始長度,元素數超過初始長度,會以初始長度為單位遞增存盤空間，

初始化:

dataType[]arrayName = new dataType[arraySize]

dataType arrayName[]= new dataType[arraySize]

arraySize為陣列的長度，

1:byte、short、int、long型別陣列，陣列元素默認初始化為0，

2:float、double型別陣列，陣列元素默認初始化為0.0，

3:char型別陣列，陣列元素默認初始化為 ，

4:boolean型別陣列，陣列元素默認初始化為false，

5:String型別陣列，陣列元素默認初始化為null，

下標越界: java.lang.ArrayIndexOutOfBoundsExceptionjava.lang.ArrayIndexOutOfBoundsException

代碼:

public class main {
public static void main(String[] args) {
//byte
System.out.println("<================byte================>");
byte[] byteName = new byte[5];
for (int i = 0; i < byteName.length; i++) {
System.out.println("第"+i+"個byteName初始化值"+byteName[i]);
}
//賦值
byte[] byName =new byte[]{5,6,7};//長度隨陣列元素增減而增減
for (int i = 0; i < byName.length; i++) {
System.out.println("第"+i+"個byName值"+byteName[i]);;
}

//short
System.out.println("<================short================>");
short[] shortName = new short[5];
for (int i = 0; i < shortName.length; i++) {
System.out.println("第"+i+"個shortName初始化值"+shortName[i]);
}
//賦值
shortName =new short[]{5,6,7};
for (int i = 0; i < shortName.length; i++) {
System.out.println("第"+i+"個shortName值"+shortName[i]);;
}

//int
System.out.println("<================int================>");
//初始化
int[] intName = new int[5];//元素不能超過定義數
int intsName[] = new int[3];
for (int i = 0; i < intName.length; i++) {
System.out.println("第"+i+"個intName初始化值"+intName[i]);
}
for (int i = 0; i < intsName.length; i++) {
System.out.println("第"+i+"個intsName初始化值"+intsName[i]);
}
//賦值
intName = new int[]{1, 2, 3,4,5,7};
//arrName.length 陣列長度 (陣列中有多少個元素) i陣列下標
for (int i = 0; i < intName.length; i++) {
System.out.println("第"+i+"個intName值"+intName[i]);
}

//long
System.out.println("<================long================>");
long[] longtName = new long[10];
for (int i = 0; i < longtName.length; i++) {
System.out.println("第"+i+"個shortName初始化值"+longtName[i]);
}
//賦值
longtName =new long[]{5,6,7,8,9};
for (int i = 0; i < longtName.length; i++) {
System.out.println("第"+i+"個longtName值"+longtName[i]);
}

//float
System.out.println("<================float================>");
float[] floatName = new float[4];
for (int i = 0; i < floatName.length; i++) {
System.out.println("第"+i+"個floatName初始化值"+floatName[i]);
}
//賦值
floatName =new float[]{(float) 4.2,6,(float)7.5,8,9};
for (int i = 0; i < floatName.length; i++) {
System.out.println("第"+i+"個floatName值"+floatName[i]);
}


//double
System.out.println("<================double================>");
double[] doubleName = new double[2];
for (int i = 0; i < doubleName.length; i++) {
System.out.println("第"+i+"個doubleName初始化值"+doubleName[i]);
}
//賦值
doubleName =new double[]{ 4.2,6.9999,7.5,8,9};
for (int i = 0; i < doubleName.length; i++) {
System.out.println("第"+i+"個doubleName值"+doubleName[i]);
}

//char
System.out.println("<================char================>");
char[] charName = new char[2];
for (int i = 0; i < charName.length; i++) {
System.out.println("第"+i+"個charName初始化值"+charName[i]);
}
//賦值
charName =new char[]{ 'x','y','z'};
for (int i = 0; i < charName.length; i++) {
System.out.println("第"+i+"個charName值"+charName[i]);
}

//boolean
System.out.println("<================boolean================>");
boolean[] booleanName = new boolean[3];
for (int i = 0; i < booleanName.length; i++) {
System.out.println("第"+i+"個booleanName初始化值"+booleanName[i]);
}
//賦值
booleanName =new boolean[]{ true,false,false};
for (int i = 0; i < booleanName.length; i++) {
System.out.println("第"+i+"個booleanName值"+booleanName[i]);
}

//String
System.out.println("<================String================>");
String[] StringName = new String[3];
for (int i = 0; i < StringName.length; i++) {
System.out.println("第"+i+"個StringName初始化值"+StringName[i]);
}
//賦值
StringName =new String[]{"鄭州","洛陽","周口"};
for (int i = 0; i < StringName.length; i++) {
System.out.println("第"+i+"個StringName值"+StringName[i]);
}
//下標越界 java.lang.ArrayIndexOutOfBoundsExceptionjava.lang.ArrayIndexOutOfBoundsException
System.out.println("start下標越界");
for (int i = 0; i < 4; i++) {
System.out.println("第"+i+"個StringName值"+StringName[i]);
}
System.out.println("end下標越界");
}
}