数组

1,Arrays.sort 排序

public class demo1 {
public static void main(String[] args) {
String [] ary = {"a","b","c","d"};
Arrays.sort(ary);#数组升序
for (String s:ary) {
System.out.print(s);
}
System.out.println("Big:"+ary[0]);
System.out.println("small:"+ary[ary.length -1]);
}
}

2,Arrays.copyof 复制#复制固定的长度

Arrays.toString()打印列表

import java.util.Arrays;

public class demo2a {
public static void main(String[] args) {
int [] aryo = {1,2,3,4,5,6};
int [] aryn = Arrays.copyOf(aryo, 6);#6表示数组长度.也可以写变量:aryo.length
System.out.println(Arrays.toString(aryn));
}

}

 

3.copy需要的的数组到另外一个数组

public class demo2a {
public static void main(String[] args) {
int [] aryo = {1,2,3,4,5,6};
int [] aryn =new int[10];
System.arraycopy(src, srcPos, dest, destPos, length); #System.arraycopy(aryo, 2, aryn, 3, 3);src:被拷贝的数组,src的位置,dest:目的数组,destpods:位置,length:长度(被拷贝数组的长度aryo.length)

System.out.println(Arrays.toString(aryn));
}

}

 4.找到数组最大值追加到数组后面

public class demo3y {
public static void main(String[] args) {
int [] ary = {1,3,9,20,60,30,40};
int max =ary[0];
for (int i=1;i<ary.length;i++) {
if (max<ary[i]) {
max = ary[i];
}
}
System.out.println("big:"+max);
ary = Arrays.copyOf(ary, ary.length+1); #扩充数组
ary[ary.length-1] = max;#最大数组赋值
System.out.println(Arrays.toString(ary));
}
}

5.随机生成10个数据.找出最小值.并且把最小值房子数组的第一位

package com.emar.cn;

import java.util.Arrays;

public class demo4m {
public static void main(String[] args) {
int [] ary = new int[10];
for(int i=0;i<ary.length;i++) {
int tmp = (int)(Math.random()*99);
ary[i] = tmp;
}
int min = ary[0];
for(int i=1;i<ary.length;i++) {
if(ary[i]<min) {
min = ary[i];
}
}
int [] newArray = new int[11];
System.arraycopy(ary, 0, newArray, 1, ary.length);
newArray[0] = min;
System.out.println(min);
System.out.println(Arrays.toString(ary));
System.out.println(Arrays.toString(newArray));
}
}

6.数组的排序

冒泡排序

package com.emar.cn;

import java.util.Arrays;

public class demo5m {
public static void main(String[] args) {
int [] ary = new int[10];
for(int i=0;i<ary.length;i++) {
int tmp = (int)(Math.random()*99);#生成任意0-99数组
ary[i] = tmp;
}
System.out.println(Arrays.toString(ary));
for (int j=0;j<ary.length-1;j++) {
if(ary[j]>ary[j+1]) {
int tmp =0;
tmp=ary[j];
ary[j]=ary[j+1];
ary[j+1]=tmp;
}
}
System.out.print(Arrays.toString(ary));
}
}

冒泡排序之顺序排序

package com.emar.cn;

import java.util.Arrays;

public class demo6s {
public static void main(String[] args) {
int [] ary = {69, 56, 33, 76, 48, 38, 57, 3, 65, 97};
for(int j=0;j<ary.length-1;j++) {
for(int i = 0;i<ary.length-1-j;i++) {
if(ary[i]>ary[i+1]) {
int tmp = 0;
tmp = ary[i];
ary[i] = ary[i+1];
ary[i+1] = tmp;
}
}
// System.out.println(Arrays.toString(ary));
}
System.out.println(Arrays.toString(ary));
}
}

 

 选择排序

package com.emar.cn;

public class demo7x {
public static void main(String[] args) {
int [] ary = {15, 3, 9, 0,20, 60, 30, 40, 2,60};
for(int i = 1;i<ary.length;i++) {
if(ary[0]>ary[i]) {
int tmp = 0;
tmp = ary[0];
ary[0] = ary[i];
ary[i] = tmp;
}
}
for(int s:ary) {
System.out.print(" "+s);
}
}
}

 

顺序

package com.emar.cn;

public class demo8s {
public static void main(String[] args) {
int [] ary = {15, 3, 9, 0,20, 60, 30, 40, 2,60};
for (int j=0;j<ary.length-1;j++) {
for(int i = j+1;i<ary.length;i++) {
if(ary[j]>ary[i]) {
int tmp = 0;
tmp = ary[i];
ary[i] = ary[j];
ary[j] = tmp;
}
}
}
for(int s:ary) {
System.out.print(" "+s);
}
}
}

 等腰三角形

package com.emar.cn;

public class demo9d {
public static void main(String[] args) {
int max=5;
for(int i=1;i<=5;i++) {
for(int j=1;j<=max-i;j++)
System.out.print(" ");
for(int k=1;k<=i*2-1;k++)
System.out.print("*");
System.out.println();
}
}
}