JAVA Study Notes --------- String API
1 determines whether the end of a character string to another string
/**
* Determining whether a string ends with another string
*/
private static void endsWithPrint() {
String str="howareyou";
boolean b=str.endsWith("ou");
System.out.println(b);
}
2 determines whether a string contains another string
/**
* Determines whether a string contains another string
*
*/
private static void containStr() {
String str="abc";
boolean b=str.contains("a");
System.out.println(b);
}
3. Finds the index of a character in a string of the first occurrence
/**
* Find index of a character in a string of the first occurrence
* int indexof(char ch)
*/
private static void indexOfPrint () {
String str="abcdefg";
you i=str.indexOf (f ');
. The System OUT .println ( "F appears in the first index position in the string:" + I );
}
- Converts a string to a byte array
/**
* Converts a string to a byte array
* byte getBytes()
*/
private static void getBytesPrint() {
String str="abc";
byte bytes[]= str.getBytes();
for (int i = 0; i < bytes.length; i++) {
System.out.println(bytes[i]);
}
5. Analyzing the content of the two strings are the same, ignoring case
/**
* boolean equals(Object obj)
Passing the resulting string *, it is determined whether the character string identical, returns true if identical
*
*
* boolean equalsIgnoreCase(String s)
* Determine the contents of two strings are the same, ignoring case
*/
private static void equalsIgnoreCaseDemo() {
String str1="abc";
String str2="ABC";
System.out.println(str1);
System.out.println(str2);
boolean b1=str1.equals(str2);
boolean b2=str2.equalsIgnoreCase(str1);
System.out.println("equals案例："+b1);
System.out.println("equalsIgnoreCase案例："+b2);
}
- The first string of uppercase letters, beginning from the second letter lowercase
/**
* A string uppercase first letter, the second letter from the beginning to lowercase
* @Param Cycle
*/
public static void conventChar(String str) {
// Get a first portion of the string
String start=str.substring(0, 1);
String end=str.substring(1);
// The first portion converts String uppercase letter lowercase string to the second portion
String big=start.toUpperCase();
String small=end.toLowerCase();
. The System OUT .println ( "original string:" + STR );
. The System OUT .println ( "transformed:" + Big + Small );
}
- Large string statistics, the number of lowercase and numeric characters
65 to 90 large write 97 to 122 smaller write numbers 48 to 57
/**
* Large string statistics, the number of lowercase and numeric characters
* @Param Cycle
*/
public static void getCount(String str) {
// define three variables
int Upper= 0;
int lower=0;
int digit= 0;
byte bytes[] =str.getBytes();
for (int i = 0; i < bytes.length; i++) {
if(65<=bytes[i]&&bytes[i]<=90) {
upper++;
}
else if (97<=bytes[i]&&bytes[i]<=122) {
lower++;
}else if (48<=bytes[i]&&bytes[i]<=57) {
digit++;
}
}
. System OUT .println ( 'uppercase characters: " + Upper + " a " );
. System OUT .println ( "lowercase characters:" + Lower + "a" );
. System OUT .println ( "numeric characters:" + digit + "a" );
for (int i = 0; i < bytes.length; i++) {
System.out.println(bytes[i]);
}