In this post, If we use Custom class in ArrayList<> and if want to check item already in ArrayList<> or not using Contain method.
Contain Method generally match all variable of the class
See.
Now I write a code for check specific variable value already contain in ArrayList<> or not.
Just we need @Override equale() and hashcode() Method in our custom class. like below.
I have created one custom class name is student. While we call contains Method then check only Student first Name. if we want to check multiple variable then we can add like below in @Override equale() and hashcode() Method.
1. Student.java
public class Student
{
private int s_rollNo = 0;
private String s_fname = "";
private String s_lname = "";
private String s_contactNumber = "";
public Student(int rollNo, String firstName, String lastName, String contactNo)
{
this.setS_rollNo(rollNo);
this.setS_fname(firstName);
this.setS_lname(lastName);
this.setS_contactNumber(contactNo);
}
public Student()
{
}
public int getS_rollNo() {
return s_rollNo;
}
public void setS_rollNo(int s_rollNo) {
this.s_rollNo = s_rollNo;
}
public String getS_fname() {
return s_fname;
}
public void setS_fname(String s_fname) {
this.s_fname = s_fname;
}
public String getS_lname() {
return s_lname;
}
public void setS_lname(String s_lname) {
this.s_lname = s_lname;
}
public String getS_contactNumber() {
return s_contactNumber;
}
public void setS_contactNumber(String s_contactNumber) {
this.s_contactNumber = s_contactNumber;
}
/*
* Here Equals method code perform when we try use contain method and the check only Student first name
* Also we can check multiple variables like below
*/
@Override
public boolean equals(Object object)
{
boolean sameSame = false;
if (object != null && object instanceof Student)
{
//for match only student rollno
//sameSame = this.s_rollNo == ((Student) object).s_rollNo;
//for match only student first name
sameSame = this.s_fname == ((Student) object).s_fname;
// also we can match both paramater here. if required
}
return sameSame;
}
@Override
public int hashCode()
{
int result = 17;
//hash code for checking rollno
//result = 31 * result + (this.s_rollNo == 0 ? 0 : this.s_rollNo);
//hash code for checking fname
result = 31 * result + (this.s_fname == null ? 0 : this.s_fname.hashCode());
return result;
}
}
2. Activity class is
MainActivity.java and I have some dummy data for testing
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends Activity
{
ArrayList arrStudents = new ArrayList();
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView txt = (TextView) findViewById(R.id.textView1);
// here add some data in ArrayList herer
arrStudents.add(new Student(1,"Ajay","asdasd","3215461321"));
arrStudents.add(new Student(2,"Rahul","ghdtd","1231231231"));
arrStudents.add(new Student(3,"Jigar","fg","9998468465"));
arrStudents.add(new Student(4,"Megha","ldZ","1212712545"));
arrStudents.add(new Student(5,"Ravi","eyr","1224575131"));
arrStudents.add(new Student(6,"Rajesh","asd","3416461213"));
// create new student for check in Arraylist Student first Name contain or not
Student std = new Student(8,"Rajesh","adfgdfg","123123123");
//Student std = new Student(4123,"Rajesh","123123","123123123");
if(arrStudents.contains(std))
{
txt.setText(std.toString() +"\n\nNew student First Name already contain in ArrayList index no: "+arrStudents.indexOf(std));
}
else
{
arrStudents.contains(std);
txt.setText(std.toString() +"\n\nNew student successfully add");
}
}
}
3.
activity_main.xml File
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="30dp" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Example code for check Student First name in arraylist Using contains method"
android:textSize="14sp"
android:textStyle="bold" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="SampleText" />
</LinearLayout>
4. ScreenShot
This code working Perfectly. Enjoy :) Thank you..
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