String, StringBuffer, StringBuilder

String

String s1 = new String("Hello");
String s2 = "Hello";

s.charAt(index);
s.toArray();
String arr[] = new String[n]

.toString

.append

equalTo()

String.indexOf()

int len = s.length();

// how to convert a STRING to a CHARACTER ARRAY
char c[] = s.toCharArray(); // HERE!!!

if (s.indexOf("IV") != -1) {sum -= 2;}
// O(m*n)

StringBuffer

StringBuilder sb = new StringBuilder(s);

StringBuilder

String[]

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String，StringBuffer, StringBuilder类的常用方法