list.Add("1")//在集合里存入数据
list.Add("2")
List是一个接口,不能实例化,创建对象时要使用他的实现类ArrayList(其他);
代码如下:
import java.io.Fileimport java.io.FileWriter
import java.io.IOException
import java.util.ArrayList
import java.util.List
class Music {
private int id
private String name
private String singer
public Music(int id, String name, String singer) {
this.id = id
this.name = name
this.singer = singer
}
public int getId() {
return id
}
public void setId(int id) {
this.id = id
}
public String getName() {
return name
}
public void setName(String name) {
this.name = name
}
public String getSinger() {
return singer
}
public void setSinger(String singer) {
this.singer = singer
}
}
public class MusicMain {
static void add(Music music, List<Music> musicList) {
musicList.add(music)
}
static void save(List<Music> musicList) throws IOException {
StringBuilder builder = new StringBuilder()
for (Music music : musicList) {
builder.append(music.getId()).append(",")
.append(music.getName()).append(",")
.append(music.getSinger()).append(System.lineSeparator())
}
File file = new File("mylist.txt")
FileWriter writer = null
try {
writer = new FileWriter(file)
writer.write(builder.toString())
} finally {
if (writer != null) {
writer.close()
}
}
}
public static void main(String[] args) {
List<Music> musicList = new ArrayList<>()
Music music1 = new Music(1, "成都.mp3", "赵雷")
add(music1, musicList)
Music music2 = new Music(2, "荷塘月色.mp3", "凤凰传奇")
add(music2, musicList)
Music music3 = new Music(3, "贵妃醉酒.mp3", "李玉刚")
add(music3, musicList)
try {
save(musicList)
} catch (IOException e) {
System.out.println("保存失败。")
}
}
}
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