JAVA string详解

package string;


import org.junit.Test;

import java.sql.SQLOutput;

public class Stringtext {
    @Test
    public void _string(){
        //substring()方法:对字符串进行切片
        String greeting="hello";
        String s=greeting.substring(0,3);
        System.out.println(s);
        

        //拼接
        String expletive="Expletive";
        String PG13="delect";
        String massage=expletive+PG13;
        System.out.println(massage);
        System.out.println("the answer is " + massage);
        String all=String.join("/","S","M","L","Xl");
        System.out.println(all);
        

        

        //检查字符串是否相等
        
        System.out.println("hello".equals(greeting)+" "+"Hello".equalsIgnoreCase("hello"));
        System.out.println(greeting.compareTo("hello")+" "+greeting.compareToIgnoreCase("Hello"));
        System.out.println("hello".substring(0,3));
        System.out.println("hello".substring(0,3)=="hel"?true:false);
        

        //空串与null
        

        //String API
        

        //构造字符串
        
        char ch=' ';
        StringBuilder builder=new StringBuilder();
        builder.append("hello");
        builder.append(ch);
        builder.append("word");
        String completedString1=builder.toString();
        System.out.println(completedString1);
        builder.setCharAt(0,'H');
        System.out.println(builder.toString());
        builder.insert(1,'!');
        System.out.println(builder.toString());
        builder.delete(1,2);
        System.out.println(builder.toString());
        
    }
}