java怎样实现读写TXT文件

主要有用到java原生态的Io类，没有第三个包。直接上代码：

import javaio;
public class write {
    public static void main(String[] args) {
        write("E://123txt", "hello");
    }
    public static void write(String path, String content) {
        try {
            File f = new File(path);
            
            if (fexists()) {
                Systemoutprintln("文件存在");
            } else {
                Systemoutprintln("文件不存在，正在创建");
                if (fcreateNewFile()) {
                    Systemoutprintln("文件创建成功！");
                } else {
                    Systemoutprintln("文件创建失败！");
                }
            }
            BufferedWriter output = new BufferedWriter(new FileWriter(f));
            outputwrite(content);
            outputclose();
        } catch (Exception e) {
            eprintStackTrace();
        }
    }
}

import javaawt; import javaio; import javaawtevent; import javaxswing; public class Test { public Test() { JFrame f=new JFrame("TEST"); Container c=fgetContentPane(); csetLayout(new FlowLayout()); JButton b=new JButton("帮助"); baddActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { try { String cmd="rundll32 urldll FileProtocolHandler file://D:/1000/helptxt ";//启动相应的windows程序来打开文件 Process p = RuntimegetRuntime()exec(cmd); } catch (Exception e1) { Systemoutprintln(e1); } } }); cadd(b); fsetBounds(100,100,300,300); fsetVisible(true); } public static void main(String arg[]) { new Test(); } } //Rundll32exe DLLname,Functionname [Arguments] ,DLLname为需要执行的DLL文件名； //Functionname为前边需要执行的DLL文件的具体引出函数；[Arguments]为引出函数的具体参数

java读取文件夹下txt文件中特定信息
import javaioBufferedReader;
import javaioFileInputStream;
import javaioIOException;
import javaioInputStreamReader;
import javautil<a href=">import javaioFile;
public class Test {
    public static void main(String[] args) {
        try {
            File file=new File("infotxt");
            new Read()readFile(file);
        }catch (Exception e){
            eprintStackTrace();
        }
    }
}import javaioBufferedReader;
import javaioFile;
import javaioFileReader;
import javautilArrayList;
public class Read {
    public void readFile(File file){
        ArrayList<String> arrayList=new ArrayList<>();
        try {
            BufferedReader bufferedReader = new BufferedReader(new FileReader(file));
            int i=1;
            String line=null;
            String person="";
            while ((line=bufferedReaderreadLine())!=null){
                String[] strings = linesplit("\\s+");
                for(String s:strings){
                    if(i!=4) {
                        person += s + ",";
                    }
                    else{
                        person+=s;
                        arrayListadd(person);
                        person="";
                        i=0;
                    }
                    i++;
                }
            }
            Systemoutprintln("{");
            for(i=0;i<arrayListsize();i++){
                String s=arrayListget(i);
                if(i!=arrayListsize()-1)
                  Systemoutprint("["+s+"];");
                else
                    Systemoutprint("["+s+"]");
            }
            Systemoutprintln("}");
        }catch (Exception e){
            eprintStackTrace();
        }
    }
}

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