Java 将数组插入arraylist的最佳方法
我尝试将数组放入数组列表中Java 将数组插入arraylist的最佳方法,java,android,Java,Android,我尝试将数组放入数组列表中 ArrayList <DNA> matingppool; 结果是 [I @ 25a0766d 但当我以某种方式显示logcat时 population [letsmat [i]].getBiner () Arrays.toString (population[letsmat[i]].getBiner ()) logcat显示器 [0, 0, 0, 1] 问题是 将数组输入池arraylist以便arraylist再次返回数组值的最佳方法是什么 还
ArrayList <DNA> matingppool;
结果是
[I @ 25a0766d
但当我以某种方式显示logcat时
population [letsmat [i]].getBiner ()
Arrays.toString (population[letsmat[i]].getBiner ())
logcat显示器
[0, 0, 0, 1]
问题是
将数组输入池arraylist以便arraylist再次返回数组值的最佳方法是什么
还是这个
matingppool.add (Arrays.toString (population [letsmat [i]]. getBiner ()));
“[I@25a0766d”是否表示数组?有两种方法可以将数组添加到arraylist中, ->第一个使用arrays.asList()的
ArrayList ArrayList=new ArrayList();
字符串[]数据=新字符串[]{“ABC”、“DEF”、“GHI”};
addAll(Arrays.asList(data));
->第二个是使用对联
ArrayList<String> arrayList=new ArrayList<>();
String[] data=new String[]{"ABC","DEF","GHI"};
Collections.addAll(arrayList, data);
ArrayList ArrayList=new ArrayList();
字符串[]数据=新字符串[]{“ABC”、“DEF”、“GHI”};
Collections.addAll(arrayList,data);
这对您很有用。要了解这说明了什么:
[I@25a0766d
,请转到下面的链接
您可以使用List
的Arrays.asList()
和addAll
方法来简洁地实现这一点。下面是一个示例代码
public static void main(String[] args) {
List<String> lst = new ArrayList<>();
String[] strLst = { "1,", "2", "3" };
lst.addAll(Arrays.asList(strLst));
System.out.println(lst);
}
请仔细阅读下面的示例。
重写
toString()
方法以打印系统输出中的类对象。如果有不清楚的地方,请发表评论
public static void main(String[] args) {
//Part1: Add toString() Method in DNA class
ArrayList<DNA> matingPool = new ArrayList<>();
matingPool.add(new DNA());
matingPool.add(new DNA());
matingPool.add(new DNA());
System.out.println(matingPool);
//Part2: use AddAll to add all the objects in one go.
ArrayList<DNA> newMatingPool = new ArrayList<>(); // You can do new ArrayList<>(matingPool) as well.
newMatingPool.addAll(matingPool);
System.out.println(newMatingPool);
}
static class DNA {
int a;
String b;
public DNA() {
this.a = 10;
this.b = "BB";
}
@Override
public String toString() {
return "DNA{" +
"a=" + a +
", b='" + b + '\'' +
'}';
}
}
publicstaticvoidmain(字符串[]args){
//第1部分:在DNA类中添加toString()方法
ArrayList matingPool=新建ArrayList();
添加(新的DNA());
添加(新的DNA());
添加(新的DNA());
系统输出打印LN(匹配池);
//第2部分:使用AddAll一次性添加所有对象。
ArrayList newMatingPool=新ArrayList();//您也可以创建新ArrayList(matingPool)。
newMatingPool.addAll(matingPool);
System.out.println(newMatingPool);
}
静态类DNA{
INTA;
b串;
公共DNA(){
这个a=10;
这个.b=“BB”;
}
@凌驾
公共字符串toString(){
返回“DNA{”+
“a=”+a+
“,b=”+b+“\”+
'}';
}
}
好的,根据我对你问题的理解,假设有一个类用户
public class User {
private String userId;
private String userName;
private String userEmail;
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserEmail() {
return userEmail;
}
public void setUserEmail(String userEmail) {
this.userEmail = userEmail;
}
public String toString() {
return userId + " " + userName + " " + userEmail;
}
}
如果我们创建类用户的数组列表
,并使用
ArrayList<User> users = new ArrayList<>();
//Add Items in ArrayList
它将打印User
ArrayList
中的值不要忘记在模型类中添加toString()
方法
希望对您有所帮助。尝试添加ArrayList list=new ArrayList();list.addAll(foo);
[I@25a0766d是数组的引用。使用for循环迭代和打印数组项
public static void main(String[] args) {
//Part1: Add toString() Method in DNA class
ArrayList<DNA> matingPool = new ArrayList<>();
matingPool.add(new DNA());
matingPool.add(new DNA());
matingPool.add(new DNA());
System.out.println(matingPool);
//Part2: use AddAll to add all the objects in one go.
ArrayList<DNA> newMatingPool = new ArrayList<>(); // You can do new ArrayList<>(matingPool) as well.
newMatingPool.addAll(matingPool);
System.out.println(newMatingPool);
}
static class DNA {
int a;
String b;
public DNA() {
this.a = 10;
this.b = "BB";
}
@Override
public String toString() {
return "DNA{" +
"a=" + a +
", b='" + b + '\'' +
'}';
}
}
public class User {
private String userId;
private String userName;
private String userEmail;
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserEmail() {
return userEmail;
}
public void setUserEmail(String userEmail) {
this.userEmail = userEmail;
}
public String toString() {
return userId + " " + userName + " " + userEmail;
}
}
ArrayList<User> users = new ArrayList<>();
//Add Items in ArrayList
for(Users user : users){
Log.d("TAG",user.toString);
}