2024-07-12
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Puto vos guys cum chordis incurrere cum linguam C disceres, sed in C lingua tantum uti potes
Character array char[10] str = "salve";Nulla dedicated String genus provisum est . In Java objecto ordinatis, chorda classis eiusque operationes specialiter provisae sunt, quae programmatoribus nostris utendi commodius est.
Contenta chordae mutari non possunt.
In Filo, omnes operationes quae pertinent ad possibilitatem modificandi contentum chordae novum obiectum creant, et quod mutatur est obiectum novum.
Verbi gratia, cum substringit quaerendo;
Aliqui dicunt: Fila immutabilia sunt, quia ordo actarum characterum intra eas a finali modificatur et ideo mutari non potest.
public static void main(String[] args) {
final char[] arr = {'h','e','l','l','o'};
arr[0] = 'H';
System.out.println(String.valueOf(arr));//Hello
// arr = new char[]{'h','o'};Error
}
Filum typum referens est et chorda non refert.
public class Test {
public static void main(String[] args) {
//1.直接赋值
String s1 = "first";
//2.new 对象
String s2 = new String("second");
//3. 创建字符数组
char[] arr = {'t','h','i','r','d'};
String s3 = new String(arr);
System.out.println(s1);
System.out.println(s2);
System.out.println(s3);
}
}
Animadverte:
String s1 = "primum";
Machina Virtualis Java (JVM) primum inspiciet num chorda "prima" iam in chorda constanti stagno existat. Si existit, relatio chordae in piscinis constanti protinus redditur;
//s1 s2 分别是new 一个新的字符串"hello"
String s1 = new String("hello");
String s2 = new String("hello");
String s3 = "Hello";
String s4 = s1;
System.out.println(s1 == s2);//false
System.out.println(s1 == s4);//true
System.out.println(s1 == s3);//false
//因为Object类中的equals()方法是==实现的，完成不了String类的需求，
//所以String对equals()实现了重写
String s1 = new String("hello");
String s2 = new String("hello");
String s3 = "Hello";
String s4 = s1;
System.out.println(s1.equals(s2));//true
System.out.println(s1.equals(s4));//true
System.out.println(s1.equals(s3));//false
3. compareTo () comparat ordinem lexicographicum, valor reditus int
/*
* 比较的方式有一下两种：
* 1.先一个一个字符相比较，如果出现不同的字符，则返回差值
* 2.如果前x个字符相等，则返回两个字符串的长度差值
* */
String s1 = new String("abc");
String s2 = new String("abcdef");
String s3 = new String("abd");
String s4 = new String("abc");
System.out.println(s1.compareTo(s2));//-3 (3-6)
System.out.println(s1.compareTo(s3));//-1
System.out.println(s1.compareTo(s4));//0
String s1 = new String("Abc");
String s2 = new String("aBcdef");
String s3 = new String("aBd");
String s4 = new String("ABc");
System.out.println(s1.compareToIgnoreCase(s2));//-3 (3-6)
System.out.println(s1.compareToIgnoreCase(s3));//-1
System.out.println(s1.compareToIgnoreCase(s4));//0
| methodo | Officium |
|---|---|
| charat charAt (int index) | Morem ad indicem positio redit. |
| int indexOf (int ch) | Recurrit locus ubi primum c apparet, et non revertitur -1 |
| int indexOf (int ch, intfromIndex) | Incipe ab indice positionis ad inveniendum locum ubi primum c apparet, et redi -1 |
| int indexOf (String str) | Recurrit locus ubi primum str apparet, nec reverti -1 |
| int indexOf (String str, intfromIndex) | Invenire primum eventum str ab ab indice positione incipiens, sine -1 . reverti |
| int lastIndexOf (int ch) | Quaere a tergo ad frontem, revertere ad locum ubi primum c apparet, nisi redeat -1 |
| int lastIndexOf(int ch, intfromIndex) | Incipe quaerere ab indice loco, et quaerere a tergo ad frontem ad locum ubi primum c apparet. |
| int lastIndexOf (String str) | Quaere inde ad frontem et locum ubi primum str non redditur. |
| int lastIndexOf (String str, intfromIndex) | Incipe investigationes ab indice positionis, et a tergo ad frontem quaere pro situ ubi primum str apparet. |
public static void main(String[] args) {
String s = "Hello, how are you today?";
System.out.println(s.charAt(2)); //l
System.out.println(s.indexOf('H')); //0
System.out.println(s.indexOf('l',2)); //从第二个开始找 2
System.out.println(s.indexOf("are")); //11
System.out.println(s.indexOf("are",12)); // 未找到-1
System.out.println(s.lastIndexOf('l')); //从后往前数 3
System.out.println(s.lastIndexOf('l',3));// 从第三个往后数 3
System.out.println(s.lastIndexOf("how"));// 7
System.out.println(s.lastIndexOf("how",6));// 未找到 -1
}
1. Conversio numerorum et chordarum
String s1 = String.valueOf(1234);
String s2 = String.valueOf(12.34);
String s3 = String.valueOf(true);
String s4 = String.valueOf(new Student("Hanmeimei", 18));
System.out.println(s1);//1234 String
System.out.println(s2);//12.34 String
System.out.println(s3);//true String
System.out.println(s4);//Student@1b6d3586
System.out.println("=================================");
int data1 = Integer.parseInt("1234");
double data2 = Double.parseDouble("12.34");
System.out.println(data1);//1234
System.out.println(data2);//12.34
2. Causa conversionis
String s1 = "hello";
String s2 = "HELLO";
System.out.println(s1.toUpperCase());//HELLO
System.out.println(s1.toLowerCase());//hello
3. Gloria ad mores ordinata et ad mores ordinata ad filum
//字符串转字符数组
String s = "What can I say!";
char[] arr = s.toCharArray();
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i]);
}
System.out.println();
//字符数组转字符串
String s1 = new String(arr);
System.out.println(s1);
4.Formatting
//格式化
String s = String.format("%d/%02d/%d",2024,07,10);
System.out.println(s);//2024/07/10
| methodo | Officium |
|---|---|
| ReponeAll filum (String regex, postea String) | Reponere omnia certa content |
| ReponeFirst filum (String regex, postea String) | Reponere primo contentus |
String s = "What can I say say!";
System.out.println(s.replaceAll("say","look"));
System.out.println(s.replaceFirst("say","SAY"));
//What can I look look!
//What can I SAY say!
| methodo | Officium |
|---|---|
| String [] String regex. | Scinditur omnes chordae |
| String [] String regex, int limit) | Scinditur filum in modum coetibus in certa forma |
//字符串拆分
String s = "字 符 串 拆 分";
String[] str = s.split(" ");
for(String i : str) {
System.out.print(i+"|");
}
System.out.println();
String[] str2 = s.split(" ",2);
for(String i : str2) {
System.out.println(i);
}
/*
* 输出：
字|符|串|拆|分|
字
符 串 拆 分
* */
/*
*拆分是特别常用的操作：
* 一定要重点掌握
*另外有些特殊字符（通配符）作为分割符可能无法正确切分, 需要加上转义.
* */
String s2 = "192.168.1.16" ;
String[] result = s2.split("\.") ;
for(String i: result) {
System.out.println(i);
}
System.out.println("\");
//为了匹配字面上的点号，你需要使用反斜杠（）来转义它，
// 但在Java字符串中，反斜杠本身也是一个转义字符，
// 所以你需要使用双反斜杠（\）来表示一个字面量上的反斜杠。
//字符串截取
String s = "What can I say!";
System.out.println(s.substring(6));//an I say!
System.out.println(s.substring(0,3));//What
String s = " yy ds ";
System.out.println(s.trim());//yy ds
Filum genus mutari non potest. Omnes modificationes nova obiecta creabunt, quae efficientis non est.
Hoc solum 10000, quod 341ms est.
Propter immutabilem naturam Stringae, ad faciliorem modificationem chordarum, Java etiam classes StringBuilder et StringBuffer praebet. Atque horum generum plerique modi sunt iidem.
Si interest, premeDocumenta Online
1ms cum usura StringBuffer.
Nota: String et StringBuilder classes directe converti non possunt. Si vis se invicem convertere, his principiis uti potes;
Sic dicta salus stamina est sicut cum multi homines ad latrinam veniunt. Una tantum conclavi hoc tempore est. Temporis hoc spatium tibi habes et nemo intrare potest. Praesens munus perficite primum, opes monopolite, deinde opes occupatas post completionem solve.
technologiae technologiae plus quam 30 annos operam dedit et in variis linguis proficit ut java, linux, javascript, php, css, etc. Multas contributiones in aperto fonte campo fecit elit documentorum statione ad communicandas quaestiones technologiarum progressus ad futuram referentiam
