1. String
1.1 String 概述
1.2 String 构造方法
String s1 = new String();
System.out.println("s1"+s1);
char[] chs = {
'a','b','c'};
String s2 = new String(chs);
System.out.println("s2"+s2);
byte[] by = {
97,89,894};
String s3 = new String(bys);
System.out.println("s3"+s3);
String s = "abc";
System.out.println("s"+s);
1.3 String对象的特点
1.3.1 通过new创建
1.3.2 通过“”创建
1.3.3 内存中的过程
字符串的比较
char[] chs = {
'a','b','c'};
String s1 = new String(chs);
String s2 = "abc";
System.out.println(s1 == s2);
System.out.println(s1.equal(s2));
案例1:用户登录
package Heima.ZiFuChuan;
import Java_Learning.util.Scanner;
public class Loadtest {
public static void main(String[] args) {
for(int i =0;i<3;i++){
String username = "110";
String password = "119";
Scanner s = new Scanner(System.in);
System.out.println("请输入用户名:");
String name = s.nextLine();
Scanner p = new Scanner(System.in);
System.out.println("请输入密码:");
String pass = p.nextLine();
if(name.equals(username) && pass.equals(password)){
System.out.println("输入正确!");
break;
}
else {
if(2-i==0){
System.out.println("你的账户已锁定!");
}else{
System.out.println("您的输入有误,"+"还有"+(2-i)+"次机会");
}
}
}
}
}
案例2:遍历字符串
- s.length() //字符串长度
- s.charAt(i) //字符串第i-1个字符
import Java_Learning.util.Scanner;
public class BianLiZiFuChuan {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入一串字符:");
String s = sc.nextLine();
for(int i =0;i<s.length();i++){
System.out.print(s.charAt(i));
}
}
}
案例3:拼接字符串
public class PinJieZiFuChuan {
public static void main(String[] args) {
int [] arr = {
1,2,3};
String z = ArrToString(arr);
System.out.println(z);
}
public static String ArrToString(int [] arr){
String s = "";
s+= "[";
for(int i=0;i<arr.length;i++){
if (i==arr.length-1){
s+=arr[i];
}else{
s+=arr[i];
s+=",";
}
}
s+="]";
return s;
}
}
案例4:字符串反转
import Java_Learning.util.Scanner;
public class FanZhuanZiFuChuan {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入需要反转的字符串:");
String s = sc.nextLine();
String recerse = Recerse(s);
System.out.println(recerse);
}
public static String Recerse(String s){
String ns = "";
ns+="[";
for(int i=s.length()-1;i>=0;i--){
if (i == 0){
ns+=s.charAt(i);
}else{
ns+=s.charAt(i);
ns+=",";
}
}
ns+="]";
return ns;
}
}