数组

public class Test01
{
public static void main(String []args){
int []a=new int[3];
a[0]=10;
a[1]=20;
a[2]=30;
for(int i=0;i<a.length;i++){
System.out.println(a[i]);
}
}
}

 

 

以上是循环输出一维数组

以下是用户手动输入

import java.util.*;
public class Test02
{
public static void main(String []args){
int []a=new int[3];
Scanner s=new Scanner(System.in);
for(int i=0;i<a.length;i++){
System.out.println(i+1);
a[i]=s.nextInt();
}
}
}

 

 

public class Test03
{
public static void main(String []args){
int []a=new int[]{100,500,300};

for(int i=0;i<a.length;i++){
System.out.println(a[i]);
}


}
}

 

 

=======！！====

public class Test03
{
public static void main(String []args){
Student []s=new Student[5];
Student stu=new Student("lili",20);
s[0]=stu;
s[1]=new Student("hh",22);


}
}

 

 

public class Test01
{
public static void main(String [] args){
for(int i=0;i<args.length;i++){
System.out.println(args[i]);
}
}
}

这个是参数在运行的时候java Test01 a b c d

 

 

 

import java.util.*;
public class Test01 {

public static void main(String[] args) {


int[] arr = {10,30,40,20,80};

int[] newArr = arrcopy(arr,8);
System.out.println(Arrays.toString(newArr));
}
public static int[] arrcopy(int[] original, int newLength ){
int [] newArr = new int[newLength];
System.arraycopy(original, 0,newArr, 0, Math.min(original.length,newLength));
return newArr;
/*Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException
at java.lang.System.arraycopy(Native Method)
at Test01.arrcopy(Test01.java:14)
at Test01.main(Test01.java:9)
*/

}
}

数组的arraycopy(Object original,int originalIndex,Object regat,int regatIndex,length)

原数组名字，起始下标，目标数据名字，起始下标，长度

 

import java.util.*;
public class Test01 {

public static void main(String[] args) {

int[] arr2 = {10,20,30,40,50,60};
arr2 = Arrays.copyOfRange(arr2,2,5);
System.out.println(Arrays.toString(arr2));

}
}

 

package com.yh.day02.arrays;

import java.util.Arrays;

public class Test03 {
public static void main(String[] args) {
int []arr2=new int[]{10,20,30,40};
arr2=Arrays.copyOf(arr2, 8);
System.out.println(Arrays.toString(arr2));
}
}

更多Arrays用法请看源码