11.字符串:

字符串替换:

如:
//替换(replace)
public static void fun1(){
String string = "zengzeleiwo";
String string1=string.replace('o','a');
System.out.println(string1);//结果:zengzeleiwa
String string2 = string.replace("ng","chinese");//结果:zechinesezeleiwo
}

字符串拼接和包含:

如:
public static void fun2(){
//包含(contains)
String str1 = "zengzelei";
boolean b1 = str1.contains("en");
System.out.println(b1);//结果为true
//拼接字符串(concat)
String str2 = "leishao";
String str3 = str1 + str2;
String str4 = str1.concat(str2);
System.out.println(str3);//结果为:zengzeleileishao
System.out.println(str4);//结果为:zengzeleileishao

}

字符串分割:

如:
public static void fun2(){
String string = "数学,语文,计算机,体育"
//分割(split)
String [] array = String.split(",");
for(String str : array){
  System.out.print(str + " ");//输出结果为:数学 语文 计算机 体育
}
}

字符串剪切:

如:
//剪切(subString)
public static void fun3(){
String string = "zengzelei";
//返回从索引往后的字符串
String string1 = string.subString(5);//输出结果为:elei
String string2 = string.subString(2,6)//输出结果为:ngze
}

字符串的大小写转换:

 //   转换大小写(toUpperCase)
    public static void fun4(){
        String string = "wanglong";
        //  转大写
        String string1 = string.toUpperCase();
        String string2 = "CHINESE";
        //  转小写(toLowerCase)
        String string3 = string2.toLowerCase();
        System.out.println(string1);  //输出结果:WANGLONG
        System.out.println(string3);  //输出结果:chinese
    }

等号与字符串equals用法:

如:
//等号的用法(=)
public class StringComparision1 {  
  
    public static void main(String[] args) {  
        String name1 = "Bob";  
        String name2 = new String("Bob");  
        String name3 = "Bob";  
        // 1st case  
        if (name1 == name2) {  
            System.out.println("The strings are equal.");  
        } else {  
            System.out.println("The strings are unequal.");  
        }  
        // 2nd case  
        if (name1 == name3) {  
            System.out.println("The strings are equal.");  
        } else {  
            System.out.println("The strings are unequal.");  
        }  
    }  
}  
//equals(相当与等号)
public class StringComparision2 {  
  
    public static void main(String[] args) {  
        String name1 = "Bob";  
        String name2 = new String("Bob1");  
        String name3 = "Bob";  
        // 1st case  
        if (name1.equals(name2)) {  
            System.out.println("The strings are equal.");  
        } else {  
            System.out.println("The strings are unequal.");  
        }  
        // 2nd case  
        if (name1.equals(name3)) {  
            System.out.println("The strings are equal.");  
        } else {  
            System.out.println("The strings are unequal.");  
        }  
    }  
}