Java String

Java Java Java String

String str = "Runoob";

"Runoob" String

String

String str2=new String("Runoob");

String new

String s1 = "Runoob"; // String String s2 = "Runoob"; // String String s3 = s1; // String s4 = new String("Runoob"); // String String s5 = new String("Runoob"); // String

[java-string-1-2020-12-01.png]

String 11 :

StringDemo.java

public class StringDemo{ public static void main(String args[]){ char[] helloArray = { 'r', 'u', 'n', 'o', 'o', 'b'}; String helloString = new String(helloArray); System.out.println( helloString ); } }

runoob

:String String

StringBuffer & StringBuilder

String length()

len 14:

StringDemo.java

public class StringDemo { public static void main(String args[]) { String site = "www.runoob.com"; int len = site.length(); System.out.println( " : " + len ); } }

 : 14

String

string1.concat(string2);

string2 string1 concat()

" ".concat("Runoob");

'+'

"Hello," + " runoob" + "!"

"Hello, runoob!"

StringDemo.java

public class StringDemo { public static void main(String args[]) { String string1 = ""; System.out.println("1" + string1 + "www.runoob.com"); } }

1www.runoob.com

printf() format()

String format() String PrintStream

String format()

System.out.printf(" " + "%f, " + " %d, " + "is %s", floatVar, intVar, stringVar);

String fs; fs = String.format(" " + "%f, " + " %d, " + " %s", floatVar, intVar, stringVar);

String

String Java String API :

SN()
1	char charAt(int index) char
2	int compareTo(Object o)
3	int compareTo(String anotherString)
4	int compareToIgnoreCase(String str)
5	String concat(String str)
6	boolean contentEquals(StringBuffer sb) StringBuffer
7	static String copyValueOf(char[] data) String
8	static String copyValueOf(char[] data, int offset, int count) String
9	boolean endsWith(String suffix)
10	boolean equals(Object anObject)
11	boolean equalsIgnoreCase(String anotherString) String String
12	byte[] getBytes() String byte byte
13	byte[] getBytes(String charsetName) String byte byte
14	void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
15	int hashCode()
16	int indexOf(int ch)
17	int indexOf(int ch, int fromIndex)
18	int indexOf(String str)
19	int indexOf(String str, int fromIndex)
20	String intern()
21	int lastIndexOf(int ch)
22	int lastIndexOf(int ch, int fromIndex)
23	int lastIndexOf(String str)
24	int lastIndexOf(String str, int fromIndex)
25	int length()
26	boolean matches(String regex)
27	boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len)
28	boolean regionMatches(int toffset, String other, int ooffset, int len)
29	String replace(char oldChar, char newChar) newChar oldChar
30	String replaceAll(String regex, String replacement) replacement
31	String replaceFirst(String regex, String replacement) replacement
32	String[] split(String regex)
33	String[] split(String regex, int limit)
34	boolean startsWith(String prefix)
35	boolean startsWith(String prefix, int toffset)
36	CharSequence subSequence(int beginIndex, int endIndex)
37	String substring(int beginIndex)
38	String substring(int beginIndex, int endIndex)
39	char[] toCharArray()
40	String toLowerCase() String
41	String toLowerCase(Locale locale) Locale String
42	String toString()
43	String toUpperCase() String
44	String toUpperCase(Locale locale) Locale String
45	String trim()
46	static String valueOf(primitive data type x) data typex
47	contains(CharSequence chars)
48	isEmpty()

AI ...

Java Character

Java StringBuffer StringBuilder

9

#0
tianqixin
429***[email protected]
455
String
```
String s = "Google";
System.out.println("s = " + s);

s = "Runoob";
System.out.println("s = " + s);
```
```
Google
Runoob
```
String

s String s = "Runoob"; "Runoob" "Google"

[string-no-modify.png]
tianqixin
tianqixin
429***[email protected]
10 (2017-02-27)

162

length() length size() :

1length() length()
2length Java length
3Java size() , , !

import java.util.ArrayList;
import java.util.List;

public class Main {

    public static void main(String[] args) {
        String array[] = { "First", "Second", "Third" };
        String a = "HelloWorld";
        List<String> list = new ArrayList<String>();
        list.add(a);
        System.out.println("array" + array.length);
        System.out.println("a" + a.length());
        System.out.println("list" + list.size());

    }
}

array3
a10
list1

9 (2017-11-21)

#0
   Helen
  109***[email protected]

70
1.%[index$][][]

4%index$index1index[]2
- '-' "0"
- '#' 81680160x
- '+' (10BigInteger816)
- ' ' (10BigInteger816)
- '0'
- ',' 103""
- '(' ('+')
d- o- xX-
```
System.out.println(String.format("%1$,09d", -3123));
System.out.println(String.format("%1$9d", -31));
System.out.println(String.format("%1$-9d", -31));
System.out.println(String.format("%1$(9d", -31));
System.out.println(String.format("%1$#9x", 5689));
//
//-0003,123
// -31
//-31
// (31)
// 0x1639
```
2.%[index$][][][.]

""
- '-' "0"
- '+'
- ' '
- '0'
- ',' 3""(fgG)
- '(' (eEfgG)
- 'e', 'E' --
- 'f' --
- 'g', 'G' --
- 'a', 'A' --
3.

c'-'
Helen
   Helen
  109***[email protected]

9 (2017-11-26)

101

String

jdk

char char

char final :

public final class String
    implements java.io.Serializable, Comparable<String>, CharSequence {
    /** The value is used for character storage. */
    private final char value[];

String char String

hunter9 (2018-03-25)

java

String a = "a";
String b = "b";
String c = a + b;

String c = new StringBuffer().append(a).append(b).toString();

class StringBuffer

String a = "saff";
String b = "saff";
String c = new String("saff");
System.out.println(a.equal(b));  // true
System.out.println(a.equal(c));  // true

hunter9 (2018-03-25)

174

String

String s1 = "abc";            // 
String s2 = new String("abc");     // 
System.out.println(s1==s2);        // false
System.out.println(s1.equals(s2)); // true

String s1="a"+"b"+"c";
String s2="abc";
System.out.println(s1==s2);
System.out.println(s1.equals(s2));

java s1 abc s2

String s1="ab";
String s2="abc";
String s3=s1+"c";
System.out.println(s3==s2);         // false
System.out.println(s3.equals(s2));  // true

ab s1, abc s2 s3StringBuilder StringBuffer append abc , toString() s3 (s3==s2) false

8 (2018-05-17)

#0

  135***[email protected]

101
JavaStringStringBuffer StringBuilder

StringJavaString immutablefinal

StringBufferSynchronized StringBuffer String StringBuffer toString() Java.lang.StringBuffer

StringBuilder StringBuilder
- String
- StringBuilder
- StringBuffer
  135***[email protected]

8 (2018-05-17)

public class Main {
    public static void main(String[] args) {
            String str1 = "hello world";
            String str2 = new String("hello world");
            String str3 = "hello world";
            String str4 = new String("hello world");
            System.out.println(str1==str2);
            System.out.println(str1==str3);
            System.out.println(str2==str4);
    }
}

false
true
false

String str1 = "hello world"; String str3 = "hello world"; "hello world" String JVM

new new

8 (2018-08-13)

String concat() + :

pubic class Demo{
    pulic satic void main(String[] args){
        String str1 = "a".concat("b").concat("c")
        String str2 = "a"+"b"+"c";
        String str3 = "abc";
        String str4 = new String("abc");
        System.out.println(str1 == str2); //false
        System.out.println(str1 == str3); //false
        System.out.println(str2 == str3); //ture
        System.out.println(str2 == str4); //false
        System.out.println(str1.equals(str4)); //true
    }
}

false
false
true
false
true

new String s = "" == false == equals() concat + concat char +

GritHub6 (2020-11-27)

--

Java

Java

Java String

StringDemo.java

StringDemo.java

StringDemo.java

String

9