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How to append data from treemap to arraylist for listview in Android?
This example demonstrate about How to append data from tree map to array list for list view in Android
Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.
Step 2 − Add the following code to res/layout/activity_main.xml.
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" android:orientation="vertical"> <EditText android:id="@+id/record" android:layout_width="match_parent" android:hint="record number" android:inputType="number" android:layout_height="wrap_content" /> <EditText android:id="@+id/name" android:layout_width="match_parent" android:hint="Enter Name" android:layout_height="wrap_content" /> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content"> <Button android:id="@+id/save" android:text="Save" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <Button android:id="@+id/refresh" android:text="Refresh" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </LinearLayout> <ListView android:id="@+id/listView" android:layout_width="match_parent" android:layout_height="wrap_content"> </ListView> </LinearLayout>
In the above code, we have taken the name and record number as Edit text, when user click on save button it will store the data into arraylist. Click on refresh button to get the changes of listview.
Step 3 − Add the following code to src/MainActivity.java
package com.example.andy.myapplication;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Map;
import java.util.TreeMap;
public class MainActivity extends AppCompatActivity {
Button save, refresh;
EditText name, record;
ArrayAdapter arrayAdapter;
ArrayList<String> array_list;
Map map = new TreeMap();
private ListView listView;
@Override
protected void onCreate(Bundle readdInstanceState) {
super.onCreate(readdInstanceState);
setContentView(R.layout.activity_main);
array_list = new ArrayList<>();
name = findViewById(R.id.name);
record = findViewById(R.id.record);
listView = findViewById(R.id.listView);
findViewById(R.id.refresh).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
arrayAdapter.notifyDataSetChanged();
listView.invalidateViews();
listView.refreshDrawableState();
}
});
findViewById(R.id.save).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!name.getText().toString().isEmpty() && !record.getText().toString().isEmpty()) {
map.put(record.getText().toString(), name.getText().toString());
array_list.clear();
array_list.addAll(map.values());
arrayAdapter = new ArrayAdapter(MainActivity.this, android.R.layout.simple_list_item_1, array_list);
listView.setAdapter(arrayAdapter);
Toast.makeText(MainActivity.this, "Inserted", Toast.LENGTH_LONG).show();
} else {
name.setError("Enter NAME");
record.setError("Enter Record");
}
}
});
}
}Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run 
icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −
In the above result, we are inserting name of treemap to arraylist.
Click here to download the project code
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