Java String

Java String的基本用法

1.计算字符串的长度

length( )计算字符串的长度

public static void main(String[] args) {
        // TODO Auto-generated method stub

        String  string = new String();
        string = "abcdefghlmn";

        System.out.println(string.length());
    }
输出结果：11

2.判断字符串是否为空

isEmpty( )判断字符串是否为空

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        String  string = new String();
        string = "abcdefghlmn";

        System.out.println(string.isEmpty());
    }
输出结果：false

3.根据索引取值

charAt( )根据索引取值

public static void main(String[] args) {
        // TODO Auto-generated method stub

        String  string = new String();
        string = "abcdefghlmn";

        System.out.println(string.charAt(0));
    }

4.判断字符串是否相等

equals( )判断两个字符串是否相等

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        String  string1 = new String();
        string1 = "abc";

        String string2 = new String();
        string2 = "abc";

        System.out.println(string1.equals(string2));
    }
输出结果：true

5.忽略大小写判断字符串是否相等

equalsIgnoreCase( )忽略大小写判断字符串是否相等

public static void main(String[] args) {
        // TODO Auto-generated method stub

        String  string1 = new String();
        string1 = "abc";

        String string2 = new String();
        string2 = "ABC";

        System.out.println(string1.equalsIgnoreCase(string2));
    }
输出结果：true

6.判断字符串是否以指定的前缀开始

startsWith( )判断字符串是否以指定的前缀开始

public static void main(String[] args) {
        // TODO Auto-generated method stub

        String  string1 = new String();
        string1 = "abcdefg";

        System.out.println(string1.startsWith("abc"));
    }

输出结果: true

7.判断字符串是否以指定的后缀结束

endsWith( )判断字符串是否以指定的后缀结束

public static void main(String[] args) {
        // TODO Auto-generated method stub

        String  string1 = new String();
        string1 = "abcdefg";

        System.out.println(string1.endsWith("fg"));
    }

输出结果：true

8.截取字符串

subString( )截取字符串

public static void main(String[] args) {
        // TODO Auto-generated method stub

        String  string1 = new String();
        string1 = "abcdefg";

        System.out.println(string1.substring(1, 4));
    }

输出结果：bcd