一 Java基础知识
1.01 数组
package com.test.testfan; public class testfan_01_01_数组 { /** * @param args */ public static void main(String[] args) { // TODO 自动生成的方法存根 int[] a = new int[]{33, 33,3, 44}; System.out.println(a[0]); System.out.println(a.length); System.out.println(a[a.length-1]);//获取最后位数据 /*for (int i = 0; i < a.length; i++) { int j = a[i]; System.out.println(j); }*/ int[] b = new int[100]; b[0] = 1; b[1] = 1; b[2] = 1; b[3] = 1; b[4] = 1; System.out.println(b.length); } }
1.02 集合
package com.test.testfan;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class testfan_01_02_集合 {
public static void main(String[] args) {
// TODO 自动生成的方法存根
List<String> list = new ArrayList<String>();
list.add("200");
String valueString = list.get(0);
System.out.println(valueString);
System.out.println(list.size());//类属性
//System.out.println(list.);//类属性
//通过数组
for (int i = 0; i < args.length; i++) {
String string = args[i];
}
List<Integer> list2 = new ArrayList<Integer>();
list2.add(200);
int value2 = list2.get(0);
for (int i = 0; i < args.length; i++) {
String string = args[i];
System.out.println(string);
}
//通过集合
for (Iterator iterator = list2.iterator(); iterator.hasNext();) {
Integer integer = (Integer) iterator.next();
System.out.println(integer);
}
//通过数组
for (int i = 0; i < args.length; i++) {
}
//通过迭代器
for (Integer integer : list2) {
System.out.println(integer);
}
}
}
package com.test.testfan;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class testfan_01_02_集合 {
public static void main(String[] args) {
// TODO 自动生成的方法存根
List<String> list = new ArrayList<String>();
list.add("200");
String valueString = list.get(0);
System.out.println(valueString);
System.out.println(list.size());//类属性
//System.out.println(list.);//类属性
//通过数组
for (int i = 0; i < args.length; i++) {
String string = args[i];
}
List<Integer> list2 = new ArrayList<Integer>();
list2.add(200);
int value2 = list2.get(0);
for (int i = 0; i < args.length; i++) {
String string = args[i];
System.out.println(string);
}
//通过集合
for (Iterator iterator = list2.iterator(); iterator.hasNext();) {
Integer integer = (Integer) iterator.next();
System.out.println(integer);
}
//通过数组
for (int i = 0; i < args.length; i++) {
}
//通过迭代器
for (Integer integer : list2) {
System.out.println(integer);
}
// 数组属性使用
List<Integer> list3 = new ArrayList<Integer>();
if(!list3.isEmpty()) {
int list4 = list3.get(0);
System.out.println(list4);
}
list3.add(200);
}
}
1.03 对象
package com.test.testfan;
public class Person {
public String name;
public int age;
private double money=1000;
public String sex;
public double getMoney() {
return money;
}
public void setMoney(double money) {
this.money = money;
}
}
package com.test.testfan;
public class testfan_01_03_对象 {
public static void main(String[] args) {
// TODO 自动生成的方法存根
Person p1 = new Person();
Person p2 = new Person();
p1.name = "zhangsan";
p1.setMoney(60000.00);
System.out.println(p1.name);
System.out.println(p1.getMoney());
System.out.println(p1);
System.out.println("-------------");
p2.name = "zhangsan9999";
p2.setMoney(90000.00);
System.out.println(p2.name);
System.out.println(p2.getMoney());
System.out.println(p2);
}
}
1.04 继承
package com.test.testfan;
public class Person {
//成员属性
public String name;
public int age;
private double money=1000;
public String sex;
//成员方法
public double getMoney() {
return money;
}
public void setMoney(double money) {
this.money = money;
}
}
package com.test.testfan;
public class Student extends Person{
@Override
public double getMoney() {
// TODO 自动生成的方法存根
//return super.getMoney();
return 9000.00;
}
}
package com.test.testfan;
public class testfan_01_04_继承 {
public static void main(String[] args) {
// TODO 自动生成的方法存根
Person p1 = new Student();
p1.name = "zhangsan";
p1.setMoney(60000.00);
System.out.println(p1.name);
System.out.println(p1.getMoney());
System.out.println(p1);
}
}
1 父类私有成员属性不进行继承
2 继承后方法进行重写 继承类 object类
1.05 Equal_ToString
Ctrl+t 查看类间的继承关系
接口 不进行实现 不可new
抽象类 部分实现 不可new
数组
ArrayList 线性结构 连续空间
LinkLIst 链表结构
集合
package com.test.testfan;
public class Person {
//成员属性
public String name;
public int age;
private double money=1000;
public String sex;
//成员方法
public double getMoney() {
return money;
}
public void setMoney(double money) {
this.money = money;
}
/* （非 Javadoc）
* @see java.lang.Object#hashCode()
*/
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + ", money=" + money + ", sex=" + sex + "]";
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
long temp;
temp = Double.doubleToLongBits(money);
result = prime * result + (int) (temp ^ (temp >>> 32));
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Person other = (Person) obj;
if (Double.doubleToLongBits(money) != Double.doubleToLongBits(other.money))
return false;
return true;
}
}
package com.test.testfan;
import java.util.ArrayList;
import java.util.List;
public class testfan_01_04_Equal_ToString {
public static void main(String[] args) {
// TODO 自动生成的方法存根
Person p1 = new Person();
Person p2 = new Person();
p1.name = "zhangsan";
p1.setMoney(90000.00);
System.out.println(p1.name);
System.out.println(p1.getMoney());
System.out.println(p1); //tostring 默认输出的是地址
System.out.println("-------------");
p2.name = "zhangsan9999";
p2.setMoney(90000.00);
System.out.println(p2.name);
System.out.println(p2.getMoney());
System.out.println(p2);
System.out.println(p2==p1); //地址比较
System.out.println(p2.equals(p1)); //值比较
List<Person> list9 = new ArrayList<Person>();
List<Object> list10 = new ArrayList<Object>();
}
}
1.06 集合1
Collection List ArrayList 数组
LinkedList
Set HashSet 集合 去重
TreeSet
Map HashMap
TreeMap
package com.test.testfan;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
public class testfan_01_05_数组 {
public static void main(String[] args) {
// TODO 自动生成的方法存根
// 数组
List<String> list = new ArrayList<String>(); //线性
list.add("1");
list.add("1");
list.add("3");
System.out.println(list.size());
List<String> list2 = new LinkedList<String>(); //分块存放
// 集合 去重
Set<String> set = new HashSet<String>();
set.add("1");
set.add("1");
set.add("3");
System.out.println(set.size());
// 集合 排序
Set<String> set2 = new TreeSet<String>();
set2.add("1");
set2.add("1");
set2.add("3");
set2.add("9");
System.out.println(set2.size());
for (String string : set2) {
System.out.println(string);
}
}
}
1.07 集合2
package com_01_testfan_02_basic;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import sun.security.ssl.KerberosClientKeyExchange;
public class Day01_05_集合2 {
public static void main(String[] args) {
// TODO 自动生成的方法存根
/**
* HashMap和 TreeMap的比较
* HashMap不进行首字母排序；
* TreeMap进行首字母排序
*/
//HashMap
Map<String, Object> map = new HashMap<String, Object>();
map.put("bname", "zhangsan");
map.put("csex", "男");
map.put("amoney", 10000);
Set<String> sets = map.keySet();
System.out.println(sets.getClass());
System.out.println(map.containsKey("33333"));
for (String string : sets) {
System.out.println("key:" + string + " value:" + map.get(string));
}
System.out.println();
//TreeMap
Map<String, Object> map2 = new TreeMap<String, Object>();
map2.put("bname", "zhangsan");
map2.put("csex", "男");
map2.put("amoney", 10000);
Set<String> sets2 = map2.keySet();
System.out.println(sets2.getClass());
System.out.println(map2.containsKey("33333"));
for (String string : sets2) {
System.out.println("key:" + string + " value:" + map2.get(string));
}
}
}