What are the commonly used methods in java

1. trim() method

The trim() method is used to remove the leading and trailing whitespace characters of a string.

Example:

public class Test {
    public static void main(String args[]) {
        String Str = new String("    www.runoob.com    ");
        System.out.print("原始值 :" );
        System.out.println( Str );

        System.out.print("删除头尾空白 :" );
        System.out.println( Str.trim() );
    }
}

Result:

原始值 :    www.runoob.com    
删除头尾空白 :www.runoob.com

2. split() method

split( ) method splits a string based on matching the given regular expression.

Note: Escape characters such as ., | and * must be added with \\.

Note: Multiple separators, you can use | as a hyphen.

Syntax:

public String[] split(String regex, int limit)

Parameters:

##regex -- Regular expression delimiter.

limit -- The number of divided parts.

Return value:

String array.

3. charAt() method

The charAt() method is used to return the character at the specified index. The index range is from 0 to length() - 1.

Syntax:

public char charAt(int index)

Parameters:

index -- The index of the character.

Return value:

Returns the character at the specified index.

Instance:

public class Test {

    public static void main(String args[]) {
        String s = "www.runoob.com";
        char result = s.charAt(8);
        System.out.println(result);
    }
}

Result:

o

4. substring() method

The substring() method returns the substring of a string.

Syntax:

public String substring(int beginIndex)
或
public String substring(int beginIndex, int endIndex)

Parameters:

beginIndex<span style="color: rgb(20, 25, 30); font-family: "Microsoft Yahei", "Hiragino Sans GB", Helvetica, "Helvetica Neue", 微软雅黑, Tahoma, Arial, sans-serif; font-size: 14px;"></span> -- Starting index (inclusive), index starts from 0.

endIndex -- End index (not included).

Return value

Substring.

Example:

public class Test {
    public static void main(String args[]) {
        String Str = new String("www.runoob.com");
 
        System.out.print("返回值 :" );
        System.out.println(Str.substring(4) );
 
        System.out.print("返回值 :" );
        System.out.println(Str.substring(4, 10) );
    }
}

Result:

返回值 :runoob.com
返回值 :runoob

Recommended tutorial:

Java tutorial

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