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String str1 = new String();
System.out.println(str1);
char[] arr = {'a', 'b', 'c'};
String str2 = new String(arr);
System.out.println(str2);
String str3 = "zhang";
System.out.println(str3);
String str4 = new String("xuezhi");
System.out.println(str4);
String str1 = new String("hello, world!");
System.out.println(str1.charAt(4));
public static void main (String[] args) {
String str1 = new String("hello, world!");
System.out.println(str1.codePointAt(4)); //o
System.out.println(str1.codePointAt(8)); //o
String str1 = new String("hello, world!");
System.out.println(str1.codePointBefore(3)); //l
System.out.println(str1.codePointBefore(4)); //l
String str1 = new String("hello, world!");
System.out.println(str1.codePointCount(0, 2)); //he
String str1 = "ba";
String str2 = "ba";
String str3 = "be";
System.out.println(str1.compareTo(str2));
System.out.println(str1.compareTo(str3));
String str1 = "ba";
String str2 = "bE";
System.out.println(str1.compareTo(str2));
// 不区分大小写
System.out.println(str1.compareToIgnoreCase(str2));
String str1 = "hello ";
String str2 = "world!";
String str3 = str1.concat(str2); // 通过concat()连接
String str4 = str1 + str2; //通过+连接
System.out.println(str3);
System.out.println(str4);
String str1 = "hello ";
String str2 = "ll";
String str3 = "ab";
System.out.println(str1.contains(str2));
System.out.println(str1.contains(str3));
String str1 = "hello ";
String str2 = "ll";
StringBuffer str3 = new StringBuffer("hello ");
System.out.println(str1.contentEquals(str2)); // String
System.out.println(str1.contentEquals(str3)); // StringBuffer
char[] arr = {'h', 'e', 'l', 'l', 'o'};
String str1 = String.copyValueOf(arr);
String str2 = String.copyValueOf(arr, 2, 2);
System.out.println(str1);
System.out.println(str2);
String str1 = "hello, world";
System.out.println(str1.endsWith("world"));
String str1 = "hello, world";
String str2 = "Hello, world";
System.out.println(str1.equals(str2));
System.out.println(str1.equalsIgnoreCase(str2));
String str1 = String.format("Hi, %s!", "Xuezhi");
String str2 = String.format("价格:%d元", 4);
String str3 = String.format("价格:%.2f元", 4.5);
System.out.println(str1);
System.out.println(str2);
System.out.println(str3);
String str1 = "abcdef";
byte[] bArr = str1.getBytes();
// 打印
for (byte item : bArr)
System.out.print(item + " ");
String str1 = "abcdef";
System.out.println(str1.hashCode());
String str1 = "abcabc";
System.out.println("a的位置是:" + str1.indexOf("a"));
System.out.println("a的位置是:" + str1.indexOf('a'));
System.out.println("a的位置是:" + str1.indexOf("a", 2));
String str1 = "abcabc";
System.out.println("a的最后位置是:" + str1.lastIndexOf("a"));
System.out.println("a的最后位置是:" + str1.lastIndexOf('a'));
System.out.println("a的最后位置是:" + str1.lastIndexOf("a", 2));
String str1 = "abcabc";
String str2 = str1.intern();
System.out.println(str2);
String str1 = "abc";
String str2 = "";
System.out.println(str1.isEmpty());
System.out.println(str2.isEmpty());
String str1 = "abc";
String str2 = "";
System.out.println(str1.length());
System.out.println(str2.length());
String str1 = "hello, world";
System.out.println(str1.matches("(.*)world(.*)"));
String str1 = "hello, world";
String str2 = str1.replace('h', 'H'); // char
String str3 = str1.replace("world", "WORLD"); // String
System.out.println(str2);
System.out.println(str3);
String str1 = "hello, world";
String str2 = str1.replaceAll("l", "L"); // char
System.out.println(str2);
String str1 = "hello, world";
String str2 = str1.replaceFirst("l", "L");
System.out.println(str2);
String str1 = "abcabcabcabc";
String[] strArr = str1.split("a");
System.out.println(strArr.length);
for (String item : strArr)
System.out.println(item);
String[] strArr2 = str1.split("a",3);
System.out.println(strArr2.length);
for (String item : strArr2)
System.out.println(item);
String str1 = "hello, world!";
System.out.println(str1.startsWith("hello"));
System.out.println(str1.startsWith("world", 7));// 偏移
String str1 = "hello, world!";
System.out.println(str1.subSequence(7, 12));
String str1 = "hello, world!";
System.out.println(str1.substring(7, 12));
System.out.println(str1.substring(7));
String str1 = "hello";
char[] charArr = str1.toCharArray();
for (char item : charArr)
System.out.print(item + " ");
String str1 = "abc DEF";
System.out.println(str1.toLowerCase());
String str1 = "abc DEF";
System.out.println(str1.toUpperCase());
String str1 = " abc def ";
System.out.println(str1.trim());
char[] charArr = {'a', 'b', 'c'};
System.out.println(String.valueOf(false));
System.out.println(String.valueOf('a'));
System.out.println(String.valueOf(charArr));
System.out.println(String.valueOf(4.5));
System.out.println(String.valueOf(4));