String类常用API

String类常用API

1.public int length()

//1.public int length()  :获取字符串的长度
String name = "我爱你中国CHINA";
System.out.println(name.length());

2.public char charAt(int index)

//2.public char charAt(int index)  :获取某个索引位置处的字符  index索引的意思
System.out.println(name.charAt(5));

//由前两个方法可以得到遍历字符串的方法
        for (int i = 0; i < name.length(); i++) {
            System.out.println(name.charAt(i));
        }

3.public char[] toCharArray()

//3.public char[] toCharArray()   :把字符串转换成字符数组
        char[] chars = name.toCharArray();
        for (int i = 0; i < chars.length; i++) {
            System.out.println(chars[i]);
        }

4.public String substring(int beginIndex, int endIndex)

//4.public String substring(int beginIndex, int endIndex)     :截取两个索引之间的字符串内容  包前不包后
System.out.println(name.substring(0, 5));

5.public String substring(int beginIndex)

//5.public String substring(int beginIndex)     :从当前索引处截取到末尾   包前不包后
System.out.println(name.substring(5));

6.public String replace(CharSequence target, CharSequence replacement)

//6.public String replace(CharSequence target, CharSequence replacement)
       //: 敏感词替换
String name1 = "我喜欢游戏， 我最喜欢游戏啦 游戏真有趣";
System.out.println(name1.replace("游戏", "学习"));

7.public boolean contains(CharSequence s)

//7.public boolean contains(CharSequence s)    :判断字符串中是否存在一些关键词
System.out.println(name1.contains("游戏"));
System.out.println(name1.contains("游戏啊"));

8.public boolean startsWith(String prefix)

//8.public boolean startsWith(String prefix)     :判断字符串是否以某个内容开头
System.out.println(name1.startsWith("我喜欢"));
System.out.println(name1.startsWith("我喜欢游戏"));
System.out.println(name1.startsWith("我喜欢游戏啊"));

9.public String[] split(String s)

//9.public String[] split(String s)      :以某个内容为结点把字符串分割成子字符串数组返回
String name2 = "A,B,C,D,E,F";
String[] split = name2.split(",");
for (int i = 0; i < split.length; i++) {
    System.out.println(split[i]);
}