String - split()

String 類別 (class) 有 split() 方法 (method)。
將一個字串分為數個token。
第一個引數為需split部分，第二個引數為該token的開始值。

public class StringTokenizing {
 public static void main(String args[]){
  String text = "To be or not to be, that is the question";
  String delimits = "[, .]";
  
  String[] tokens = text.split(delimits, 0);
  String[] tokens1 = text.split(delimits, 5);
  System.out.println("Num of tokens: " + tokens.length);
  for(String token:tokens){
   System.out.println(token);
  }
  System.out.println("Num of tokens: " + tokens1.length);
  for(String token:tokens1){
   System.out.println(token);
  }
 }
}

String - subString()

String 類別 (class) 有 subString() 方法 (method)。
subString可由一個字串取出一個子字串。

public class Test {
 public static void main(String[] args){
  String text = "To be or not to be, that is the question;"+
    " Whether 'tis nobler in the mind to suffer"+
    " the slings and arrows of outrageous fortune,"+
    " or to take arms against a sea of troubles," +
    " and by opposing end them?";
  String sub1 = text.substring(171);
  String sub2 = text.substring(20, 41);
  System.out.println(sub1);
  System.out.println(sub2);
 }
}

String - indexOf()

String 類別 (class) 有 compareTo() 方法 (method)。
indexOf()可用來搜尋字串，並回傳字串所在的數值。

public class Test {
 public static void main(String[] args){
  String text = "To be or not to be, that is the question;"+
    " Whether 'tis nobler in the mind to suffer"+
    " the slings and arrows of outrageous fortune,"+
    " or to take arms against a sea of troubles," +
    " and by opposing end them?";
  int aIndex = -1;
  int count = 0;
  while((aIndex = text.indexOf("the", ++aIndex)) > -1){
   ++count;
  }
  System.out.println("Num of 'the' is : " + count);
 }
}

String-compareTo()

String 類別 (class) 有 compareTo() 方法 (method)。 若str1 > str2 回傳true str2 > str1 回傳false 相等回傳0

public class SequenceString {
 public static void main(String args[]){
  String string1 = "A";
  String string2 = "To";
  String string3 = "Z";
  
  String string1Out = "\"" + string1 + "\"";
  String string2Out = "\"" + string2 + "\"";
  String string3Out = "\"" + string3 + "\"";
  
  if(string1.compareTo(string3) < 0){
   System.out.println(string1Out + " is less than " + string3Out);
  }else{
   if(string1.compareTo(string3) > 0){
    System.out.println(string1Out + " is greater than " + string3Out);
   }else{
    System.out.println(string1Out + " is equal to  " + string3Out);
   }
  }
  if(string2.compareTo(string1) < 0){
   System.out.println(string2Out + " is less than " + string1Out);
  }else{
   if(string2.compareTo(string1) > 0){
    System.out.println(string2Out + " is greater than " + string1Out);
   }else{
    System.out.println(string2Out + " is equal to  " + string1Out);
   }
  }
 }
}

String - charAt()

String 類別 (class) 有 charAt() 方法 (method)。 可取出String 物件裡的某個字元。

public class StringCharacters {
 public static void main(String args[]){
  String text = "To be or not to be, that is the question;"+
     " Whether 'tis nobler in the mind to suffer"+
     " the slings and arrows of outrageous fortune,"+
     " or to take arms against a sea of troubles," +
     " and by opposing end them?";
  
  int spaces = 0;
  int vowels = 0;
  int letters = 0;
  
  for(int i=0; i < text.length(); i++){
   char ch = Character.toLowerCase(text.charAt(i));
   
   if(ch == 'a' || ch =='e' || ch == 'i' || ch == 'o'|| ch =='u'){
    vowels ++;
   }
   if(Character.isLetter(ch)){
    letters ++;
   }
   if(Character.isSpace(ch)){
    spaces ++;
   }
  }
  
  System.out.println("vowels is : " + vowels + "\nconstants is : " + (letters - vowels) +
    "\nspaces is : " + spaces);
 }
}

String - equals()

String 類別 (class) 有 equals() 方法 (method)。 將 兩個str做比較。

public class MatchStrings {
 public static void main(String args[]){
  String string1 = "Hello World ";
  String string2 = "java";
  String string3 = "Hello World java";
  
  string1 += string2;
  
  System.out.println("Try");
  
  if(string1.equals(string3)){
   System.out.println("s1 and s3 are equls");
  }else{
   System.out.println("s1 and s3 are different");
  }
  
 }
}

String - concat()

String 類別 (class) 有 concat() 方法 (method) ，將 str 接到字串的後面。

public class Test {
 public static void main(String[] args){
  String x1 = "xyz";
  String x2 = "abc";
  
  System.out.println(x1+x2);
  x1 = "tuv";
  System.out.println(x1);
  x2 = "def";
  System.out.println(x2);
  x2 = x2.concat("def");
  System.out.println(x2);
  
 }
}