First App Android: How To Create An Android App With Android Studio (Hello World and Simple Login with Toast)

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Here’s the few step to make first app on android studio, just 5 steps. Okay, let’s begin.

1. First, create Main.java for main activity. Here’s the code:

package com.example.helloworld;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;

public class Main extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button btnNext = (Button) findViewById(R.id.btnNext);
        btnNext.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onClickNext();
            }
        });

        Button btnExit = (Button) findViewById(R.id.btnExit);
        btnExit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
            }
        });

    }

    public void onClickNext() {
        Intent intent = new Intent().setClass(this, LoginActivity.class);
        startActivity(intent);
    }

}

2. Second, put code below to main.xml for main activity interface

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" android:text="@string/hello_world"/>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="50dip"
        android:orientation="horizontal"
        android:gravity="center">

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Next"
            android:id="@+id/btnNext"/>

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="10dip"
            android:text="Exit"
            android:id="@+id/btnExit"/>


    </LinearLayout>

</LinearLayout>

main.xml

3. Third, create new activity for LoginActivity.java

package com.example.helloworld;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class LoginActivity extends AppCompatActivity {

    Button btnLogin, btnExit;
    EditText txtUser, txtPass;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);

        btnLogin = (Button) findViewById(R.id.btnLogin);
        btnExit = (Button) findViewById(R.id.btnExit);
        txtUser = (EditText) findViewById(R.id.txtUser);
        txtPass = (EditText) findViewById(R.id.txtPass);

        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String txt = "Your username is: "
                        + txtUser.getText().toString()
                        + "\nYour password is: "
                        + txtPass.getText().toString();
                Toast.makeText(LoginActivity.this, txt.trim(),
                        Toast.LENGTH_LONG).show();
            }
        });

        btnExit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
                return;
            }
        });
    }
}

4. Fourth, then put this code to login.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="5dip">

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="50dip"
        android:orientation="horizontal">

        <TextView
            android:layout_width="80dip"
            android:layout_height="wrap_content"
            android:text="Username:"
            android:id="@+id/lblUser"/>

        <EditText
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/txtUser"/>

    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="50dip"
        android:orientation="horizontal">

        <TextView
            android:layout_width="80dip"
            android:layout_height="wrap_content"
            android:text="Password:"
            android:id="@+id/lblPass"/>

        <EditText
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/txtPass"
            android:password="true" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dip"
        android:gravity="right"
        android:id="@+id/linearLayout3">

        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:text="Login"
            android:id="@+id/btnLogin"/>

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Exit"
            android:id="@+id/btnExit"/>

    </LinearLayout>

</LinearLayout>

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5. Fifth, modify your AndroidManifest.xml like this:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.helloworld" >

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >

        <activity
            android:name=".Main"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name=".LoginActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </activity>

    </application>
<uses-sdk android:minSdkVersion="7"/>
</manifest>

Finally, Run your app with emulator or your mobile device

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you can set textview as a password field for make the text of password to asterisk or dot like the picture above

thanks for reading my blog, any error or something you can comment below

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