String类
public class StringStringBuffer {
public static void main(String args[])
{
//创建字符串变量
System.out.println("创建字符串变量\n");
String name = " Hello World! ";
//求字符串长度
System.out.println("求字符串长度\n");
int len = name.length();
//length()是属于String类的方法
System.out.println(len);
//连接字符串
System.out.println("\n连接字符串\n");
String fun = ("My name is Java!");
System.out.println(name+fun);
//字符串查找
System.out.println("\n字符串查找\n");
System.out.println(fun.indexOf("n"));
System.out.println(fun.lastIndexOf("a"));
//字符串截取
System.out.println("\n字符串截取\n");
System.out.println(name.substring(3,8));
//去除空格
System.out.println("\n去除空格\n");//去掉字符串首尾的空格
System.out.println("去除空格前的长度"+name.length());
System.out.println("去除空格后的长度"+name.trim().length());
//字符串替换
System.out.println("\n字符串替换\n");
String newname =name.replace("o","O");
System.out.println(newname);
//判断字符串的开始与结尾
System.out.println("\n判断字符串的开始与结尾\n");
System.out.println(name.startsWith("H"));
System.out.println(name.endsWith("s"));
//判断字符串是否相等
System.out.println("\n判断字符串是否相等\n");
System.out.println(name.equals(fun));
System.out.println(name.equalsIgnoreCase(fun)); // 不区分大小写
//按字典顺序比较两个字符串 1 -1 0
System.out.println("\n按字典顺序比较两个字符串 1 -1 0\n");
System.out.println(name.compareTo(fun));
//字母大小写转换
System.out.println("\n字母大小写转换\n");
String Name1 = name.toLowerCase();
String Name2 = name.toUpperCase();
System.out.println(Name1);
System.out.println(Name2);
//字符串分割
System.out.println("字符串分割");
String code = "123,234,111";
System.out.println(code);
String []code1=code.split(",",3);
for(int i=0;i<3;i++)
{System.out.println(code1[i]);}
}
}
SringBuffer类
public class StringBuffer_{
public static void main(String []args){
StringBuffer s = new StringBuffer("向");
s.append("死");
s.append("而生");
System.out.println(s);
}
}
Date类和Arrays类
import java.util.*;
public class DA
{
public static void main(String args[]){
//初始化Date对象
Date date = new Date();
//使用toString获取当前日期时间
System.out.println(date.toString());
//printf格式化日期输出(%n换行)
//%tc 全部日期和时间信息
System.out.printf("全部日期和时间信息:%tc%n",date);
//%tf 年-月-日格式
System.out.printf("年-月-日格式:%tF%n",date);
//月/日/年格式
System.out.printf("月-日-年格式:%tD",date);
int arrays[]= new int[10];
//用fill方法给数组赋值Array.fill(数组名,fromindex(包括),toindex(不包括),value)
Arrays.fill(arrays,5);
Arrays.fill(arrays,1,3,7);//arrays[1],arrays[2]赋值为7
System.out.println("赋值后数组:");
for(int i=0;i<arrays.length;i++)
System.out.println(arrays[i]);
//用sort方法排序(默认升序)
Arrays.sort(arrays);
System.out.println("排序后数组");
for(int j=0;j<arrays.length;j++)
System.out.println(arrays[j]);
//判断数组是否相等
int krrays[]=new int [10];
Arrays.fill(krrays,9);
System.out.println(Arrays.equals(arrays,krrays));
//查找数组元素
System.out.println("返回数组元素的位置");
System.out.println(Arrays.binarySearch(arrays,5));
}
}