String字符串操作

char chars[] ={'a','b','c'};
String s = new String(chars);
int len = s.length();//字符串长度
System.out.println(chars);//ab
System.out.println(s);//abc
System.out.println(len);//3
char ch = "zhangpei".charAt(5);下标从0开始
System.out.println(ch);//p

String str = "this is a demo of the getChars method.";
char buf[] = new char[20];
str.getChars(10,16,buf,1);
System.out.println(str);
System.out.println(buf);

String str = "this is a demo of the getChars method.";
char char1[] = new char[50];
char1 = str.toCharArray();//将此字符串转换为一个新的字符数组。
System.out.println(char1);

//字符串与二进制字符之间的转换，网络传输时需要将普通的字符串转化为字符流byte

String str = "this is a demo of the getChars method.";
byte byte1[] = new byte[50];
byte1 = str.getBytes();
System.out.println(byte1);
String str1 = new String(byte1);
System.out.println(str1);

String str1 = "zhangpei";
String str2 = "zhangpei";
String str3 = "ZHANGPEI";
System.out.println(str1.equals(str2));//true
System.out.println(str1.equalsIgnoreCase(str2));//true
System.out.println(str1.equals(str3));//false
System.out.println(str1.equalsIgnoreCase(str3));//true

按字典顺序比较两个字符串。该比较基于字符串中各个字符的 Unicode 值。按字典顺序将此 String 对象表示的字符序列与参数字符串所表示的字符序列进行比较。如果按字典顺序此 String 对象位于参数字符串之前，则比较结果为一个负整数。如果按字典顺序此 String 对象位于参数字符串之后，则比较结果为一个正整数。如果这两个字符串相等，则结果为 0；compareTo 只在方法 equals(Object) 返回 true 时才返回 0

System.out.println("a".compareTo("b"));//-1
System.out.println("b".compareTo("a"));//1
System.out.println("a".compareTo("a"));//0
System.out.println("ab".compareTo("ba"));//-1

String s1 = "b";
String s2 = "B";
System.out.println(s1.compareTo(s2));//32
System.out.println(s1.compareToIgnoreCase(s2));//0

equals()方法比较字符串对象中的字符，==运算符比较两个对象是否引用同一实例。

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

String s1 = "hello";
String s2 = s1;
System.out.println(s1.equals(s2));//true
System.out.println(s1==s2);//true