本文目录一览：
- 1、java对文件名的几个操作，获取文件扩展名，去掉扩展名
- 2、anm.java:36: 错误: eagle不是抽象的, 并且未覆盖aif中的抽象方法climbtree() class eagle extends anima
- 3、kafka-eagle安装踩坑
- 4、java编写Animal类
- 5、java 怎么用命令进入指定的目录
- 6、一道JAVA题，在线等答案，求高手帮忙~
java对文件名的几个操作，获取文件扩展名，去掉扩展名
/*
* Java文件操作 获取文件扩展名
*
* Created on: 2011-8-2
* Author: blueeagle
*/
public static String getExtensionName(String filename) {
if ((filename != null) (filename.length() 0)) {
int dot = filename.lastIndexOf('.');
if ((dot -1) (dot (filename.length() - 1))) {
return filename.substring(dot + 1);
}
}
return filename;
}
/*
* Java文件操作 获取不带扩展名的文件名
*
* Created on: 2011-8-2
* Author: blueeagle
*/
public static String getFileNameNoEx(String filename) {
if ((filename != null) (filename.length() 0)) {
int dot = filename.lastIndexOf('.');
if ((dot -1) (dot (filename.length()))) {
return filename.substring(0, dot);
}
}
return filename;
}
anm.java:36: 错误: eagle不是抽象的, 并且未覆盖aif中的抽象方法climbtree() class eagle extends anima
你的eagle类实现了aif接口，但是没有重写aif接口中的climbtree方法，cat类也是，没有重写aif接口中的fly方法，接口中的方法是必须全部被实现类重写的
kafka-eagle安装踩坑
1.遇到的第一个坑是启动eagle失败，查看logs/error.log和ke_console.out才知道是虚拟机内存不足，java虚拟机需要1G内存，而虚拟机本身才有1G
解决办法：直接修改虚拟机内存
2.JMXConnector报错，在kafka下面的kafka-server-start.sh文件里添加 jmx端口9999
3.mysql服务器连接一直报错
java编写Animal类
//接口的定义
interface Animal {
public void bark();
public void fly();
}
//老鹰类
class Eagle implements Animal {
public void bark() {
System.out.println("老鹰叫");
}
public void fly() {
System.out.println("老鹰飞");
}
}
//鸽子类
class Pigeon implements Animal{
public void bark() {
System.out.println("鸽子叫");
}
public void fly() {
System.out.println("鸽子飞");
}
}
//测试类
public class Test{
public static void main(String[] args){
Animal pigeon = new Pigeon();
Animal eagle = new Eagle();
pigeon.bark();
pigeon.fly();
eagle.bark();
eagle.fly();
}
}
如果还有什么疑问..请百度Hi我.. 我会进一步的为你解答..
java 怎么用命令进入指定的目录
这个跟java没关系，完全是dos命令
在dos里输入 c: 回车，就到C盘了，其他类似
如果C盘下有abc文件夹，输入cd abc 就可以进去了，cd就是进入文件夹的命令
cd..是退回到上一层目录
cd/ 是退回到根目录
一道JAVA题，在线等答案，求高手帮忙~
public class Test {
public static void main(String[] args) {
IBird chicken1 = new Chicken("Chicken 1", "Red", 3.5F);
IBird chicken2 = new Chicken("Chicken 1", "Green", 11.5F);
IBird chicken3 = new Chicken("Chicken 1", "Blue", 7.5F);
IBird eagle1 = new Eagle("Eagle 1", "Black", 100F);
IBird eagle2 = new Eagle("Eagle 2", "White", 35F);
System.out.println("Chicken 1 can reach 10 height? " + chicken1.isReachable(10));
System.out.println("Chicken 2 can reach 10 height? " + chicken2.isReachable(10));
System.out.println("Chicken 3 can reach 10 height? " + chicken3.isReachable(10));
System.out.println("Eagle 1 can reach 10 height? " + eagle1.isReachable(10));
System.out.println("Eagle 2 can reach 10 height? " + eagle2.isReachable(10));
if(chicken1.isReachable(10F)){
chicken1.printBirdInformation();
}
if(chicken2.isReachable(10F)){
chicken2.printBirdInformation();
}
if(chicken3.isReachable(10F)){
chicken3.printBirdInformation();
}
if(eagle1.isReachable(10F)){
eagle1.printBirdInformation();
}
if(eagle2.isReachable(10F)){
eagle2.printBirdInformation();
}
}
}
interface IBird{
public void setName(String name);
public void setColor(String color);
public void setMaxFlyingHeight(float height);
public boolean isReachable(float height);
public void printBirdInformation();
}
class Chicken implements IBird{
private String name;
private String color;
private float maxFlyingHeight;
private int eggs;
public Chicken(String name, String color, float maxFlyingHeight){
this.name = name;
this.color = color;
this.maxFlyingHeight = maxFlyingHeight;
}
public int getEggs() {
return eggs;
}
public void setEggs(int eggs) {
this.eggs = eggs;
}
public boolean isReachable(float height) {
return height = maxFlyingHeight;
}
public void printBirdInformation() {
System.out.println("Chicken's information: name: " + this.name + ", color: " + this.color);
}
public void setColor(String color) {
this.color = color;
}
public void setMaxFlyingHeight(float height) {
this.maxFlyingHeight = height;
}
public void setName(String name) {
this.name = name;
}
}
class Eagle implements IBird{
private String name;
private String color;
private float maxFlyingHeight;
private double flyingDistance;
public Eagle(String name, String color, float maxFlyingHeight){
this.name = name;
this.color = color;
this.maxFlyingHeight = maxFlyingHeight;
}
public double getFlyingDistance() {
return flyingDistance;
}
public void setFlyingDistance(double flyingDistance) {
this.flyingDistance = flyingDistance;
}
public boolean isReachable(float height) {
return height = maxFlyingHeight;
}
public void printBirdInformation() {
System.out.println("Eagle's information: name: " + this.name + ", color: " + this.color);
}
public void setColor(String color) {
this.color = color;
}
public void setMaxFlyingHeight(float height) {
this.maxFlyingHeight = height;
}
public void setName(String name) {
this.name = name;
}
}
