[Java] common interview questions Java String commonly used method

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Java String commonly used method

1. length () of the length of the string

   String a = "Hello Word!";
   System.out.println(a.length);
   

   Result output 10 is the string length.

2. the charAt () interception of a character

   String a = "Hello Word";
   System.out.println(a.charAt(1));
   

   Output result is a string of characters is a subscript of e 1.

3. GetChars () taken by the plurality of other characters in the string receiving

   String a = "Hello Word";
   char[] b = new char[10];
   a.getChars(0, 5, b, 0);
   System.out.println(b);
   

   Result is output Hello, wherein the first parameter is the initial index to intercept the string (int sourceStart), the second parameter is a 5 index (int sourceEnd) to be taken after the end of the string i.e. the actual intercepted subscripts int sourceEnd-1, the third parameter is the received character string (char target []), the last parameter string was received reception start position.

4. the getBytes () string into a byte array

   String a = "Hello Word";
   byte b[] = a.getBytes();
   System.out.println(new String(b));
   

   Hello Word for result output byte array.

5. toCharArray () string into a character array

   String a = "Hello Word";
   char[]b = a.toCharArray();
   System.out.println(b);  
   

   Hello Word output is the result of an array of characters.

6. the equals () and equalsIgnoreCase () Compares two strings are equal, the former case-sensitive, the latter does not distinguish between

   String a = "Hello Word";
   String b = "hello word";
   System.out.println(a.equals(b));
   System.out.println(a.equalsIgnoreCase(b));
   

   The results for the first output is false, the second is true.

7. startsWith () and endsWith () determines if a string is beginning or end of a particular character

   String a = "Hello Word";
   System.out.println(a.startsWith("ee"));  
   System.out.println(a.endsWith("rd"));
   

   The results output from the first to false, the second is true.

8. the toUpperCase () and the toLowerCase () to convert a string uppercase or lowercase

   String a = "Hello Word";
   System.out.println(a.toUpperCase());
   System.out.println(a.toLowerCase());
   

   The first output result is "HELLO WORD", the second as "hello word".

9. the concat () connecting the two strings

   String a = "Hello Word";
   String b = "你好";
   System.out.println(b.concat(a));
   

   The resulting output is "Hello Hello Word".

10. TRIM () to remove the start and end of the space

    String a = "    Hello Word   ";
    System.out.println(a.trim());
    

    The resulting output is "Hello Word".

11. the substring () String taken

    String a = "Hello Word";
    System.out.println(a.substring(0, 5));
    System.out.println(a.substring(6));
    

    The first output result is "Hello", the first parameter 0 (beginIndex) is taken the start position, the second parameter 5 (endIndex) is taken to the end position, the second output result is "Word", parameter 6 (beginIndex) is the start position taken.

12. indexOf () and lastIndexOf () the former is to find the place where I first occurrence of a character or string, which is the place to find the last occurrence of a character or a string

    String a = "Hello Word";
    System.out.println(a.indexOf("o"));
    System.out.println(a.lastIndexOf("o"));
    

    The first result output is 4, o is the first occurrence of the subscript, the second is 7, the last occurrence of the subscript o.

13. the compareTo () and compareToIgnoreCase () Size lexicographically compare two strings, the former case-sensitive, the latter does not distinguish between

    String a = "Hello Word";
    String b = "hello word";
    System.out.println(a.compareTo(b));
    System.out.println(a.compareToIgnoreCase(b)); 
    

    The results output from the first to -32, to 0 second, the same size in the two strings in the dictionary order, 0 is returned.

14. the replace () Replace

    String a = "Hello Word";
    String b = "你好";
    System.out.println(a.replace(a, b));
    System.out.println(a.replace(a, "HELLO WORD"));
    System.out.println(b.replace("你", "大家"));
    

    The results of the first output is "Hello", the second is "HELLO WORD", the third is "Hello everyone."