String 类的常用方法-蒲公英云

1，求长判相等：

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        String string =reader .next();
        int n=string .length();
        System.out.println(n);
        String string2 =reader.next();
        if(string .equals(string2))
        {
            System.out.println("YES");
        }
        else
        {
            System.out.println("NO");
        }
        reader.close();
    }
}
akkhhhjjkk
10
akkhhhjjkk
YES

2：判头判尾是否相同

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        String string =reader .next();
        String string2 =reader.next();
        if(string .startsWith(string2))
        {
            System.out.println("YES");
        }
        else
        {
            System.out.println("NO");
        }
        reader.close();
        if(string .endsWith(string2))
        {
            System.out.println("YES");
        }
        else
        {
            System.out.println("NO");
        }
    }
}
aaabbb
aaa
YES

3：判断当前字符串的某个位置间的子字符串和另一个字符串是否相等

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        String string =reader .next();
        String string2 =reader.next();
        if(string .regionMatches(0, string2, 0, 3))
        {
            System.out.println("YES");
        }
        else
        {
            System.out.println("NO");
        }
        reader.close();
    }
}
eeeccc
eee
YES
import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        String string =reader .next();
        String string2 =reader.next();
        if(string .regionMatches(2, string2, 0, 3))
        {
            System.out.println("YES");
        }
        else
        {
            System.out.println("NO");
        }
        reader.close();
    }
}
eeccceee
ccc
YES

该方法的重载方法：（忽略大小写）

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        String string =reader .next();
        String string2 =reader.next();
        if(string .regionMatches(true,0, string2, 0, 3))
        {
            System.out.println("YES");
        }
        else
        {
            System.out.println("NO");
        }
        reader.close();
    }
}
aaaVVV
AAA
YES

4 判断两个字符串按字典序列比较大小

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        while(reader.hasNext())
        {
        String string =reader .next();
        String string2 =reader.next();
        if(string .compareTo(string2)==0)
        {
            System.out.println("YES");
        }
        if(string .compareTo(string2)>0)
        {
            System.out.println("NO I LOVE");
        }
        if(string .compareTo(string2)<0)
        {
            System.out.println("NO I DONT LOVE");
        }
        }
        reader.close();
    }
}
aaaccc
aaaccc
YES
abcde
b
NO I DONT LOVE
abcde
abbde
NO I LOVE

5 判断当前字符串是否包含另一个字符串

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        while(reader.hasNext())
        {
        String string =reader .next();
        String string2 =reader.next();
        if(string .contains(string2))
        {
            System.out.println("I LOVE YOU");
        }
        else
        {
            System.out.println("I DONT LOVE YOU");
        }
        }
        reader.close();
    }
}
aaaaaa
ccc
I DONT LOVE YOU
aaaa
a
I LOVE YOU

6 从开端和当前位置分别检索有无此字符串：

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        while(reader.hasNext())
        {
        String string =reader .next();
        String string2 =reader.next();
        int n=string .indexOf(string2);
        if(n!=-1)
        {
            System.out.println(n);
        }
        else
        {
            System.out.println("NO");
        }
        }
        reader.close();
    }
}
aaaaaa
cccccc
NO
aaaaaa
a
0
aaaaaa
bbbbaa
NO
abcdabd
abd

从当前位置开始检索：

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        while(reader.hasNext())
        {
        String string =reader .next();
        String string2 =reader.next();
        int n=string .indexOf(string2,4);
        if(n!=-1)
        {
            System.out.println(n);
        }
        else
        {
            System.out.println("NO");
        }
        }
        reader.close();
    }
}
ILOVEYOU
YOU
5
ILOVEYOU
LOVE
NO

7 获取模式串的子串：

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        while(reader.hasNext())
        {
        String string =reader .next();
        String string2 =string.substring(1,5);
        System.out.println(string2);
        }
        reader.close();
    }
}
ILOVEYOU
LOVE

8将一个字符串去掉空格（仅限前后）：

import java.util.*;
public class Main 
{
    public static void main(String[] args) 
    {
        Scanner reader =new Scanner(System.in);
        while(reader.hasNext())
        {
        String string =reader .nextLine();
        String string2 =string.trim();
        System.out.println(string2);
        }
        reader.close();
    }
}
I LOVE YOU
I LOVE YOU
 I LOVE YOU （后面有空格）
I LOVE YOU