(1)Calling one Activity from another in Android
用法:

Intent launchActivity2 = new Intent(Activity1.this, Activity2.class);

you can simply launch the activity by running:
startActivity(launchActivity2 );

utton next = (Button) findViewById(R.id.TEST);
next.setOnClickListener(new View.OnClickListener() {
    public void onClick(View view) {
        Intent myIntent = new Intent( view.getContext(), MyActivity.class);
        startActivity(myIntent);
    }
});

參考資料:http://hmkcode.com/android-start-another-activity-within-the-same-application/

(2)Android – Passing Data to Another Activities

(1)MainActivity.java

package com.hmkcode.android;

import android.os.Bundle;

import android.app.Activity;

import android.content.Intent;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

public class MainActivity extends Activity implements OnClickListener {

    Button btnStartAnotherActivity;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        btnStartAnotherActivity = (Button) findViewById(R.id.btnPassData);

        btnStartAnotherActivity.setOnClickListener(this);

}

    @Override

    public void onClick(View view) {

        // 1. create an intent pass class name or intnet action name 

        Intent intent = new Intent("com.hmkcode.android.ANOTHER_ACTIVITY");

        // 2. put key/value data

        intent.putExtra("message", "Hello From MainActivity");

        // 3. or you can add data to a bundle

        Bundle extras = new Bundle();

        extras.putString("status", "Data Received!");

        // 4. add bundle to intent

        intent.putExtras(extras);

        // 5. start the activity

        startActivity(intent);

}

}

(2)AnotherActivity.java 

package com.hmkcode.android;
 
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;
 
public class AnotherActivity extends Activity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_another);
 
        // 1. get passed intent 
        Intent intent = getIntent();
 
        // 2. get message value from intent
        String message = intent.getStringExtra("message");
 
        // 3. show message on textView 
        ((TextView)findViewById(R.id.tvMessage)).setText(message);
 
        // 4. get bundle from intent
        Bundle bundle = intent.getExtras();
 
        // 5. get status value from bundle
        String status = bundle.getString("status");
 
        // 6. show status on Toast
        Toast toast = Toast.makeText(this, status, Toast.LENGTH_LONG);
        toast.show();
    }
}

(3) Define All Activities in the Manifest XML File<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.hmkcode.android"
    android:versionCode="1"
    android:versionName="1.0" >
 
    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />
 
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
 
        <activity
            android:name="com.hmkcode.android.MainActivity"
            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="com.hmkcode.android.AnotherActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="com.hmkcode.android.ANOTHER_ACTIVITY" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
    </application>
 
</manifest>
參考資料:http://hmkcode.com/android-passing-data-to-another-activities/
(3)Android – Passing Java Object to Another Activity(3.1) MainActivity.java
package com.hmkcode.android;
 
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
 
public class MainActivity extends Activity implements OnClickListener {
 
    Button btnPassObject;
    EditText etName, etAge;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        btnPassObject = (Button) findViewById(R.id.btnPassObject);
        etName = (EditText) findViewById(R.id.etName);
        etAge = (EditText) findViewById(R.id.etAge);
 
        btnPassObject.setOnClickListener(this);
    }
 
    @Override
    public void onClick(View view) {
 
        // 1. create an intent pass class name or intnet action name 
        Intent intent = new Intent("com.hmkcode.android.ANOTHER_ACTIVITY");
 
        // 2. create person object
        Person person = new Person();
        person.setName(etName.getText().toString());
        person.setAge(Integer.parseInt(etAge.getText().toString()));
 
        // 3. put person in intent data
        intent.putExtra("person", person);


        // 4. start the activity
        startActivity(intent);
    }
 
}
 
(3.2) AnotherActivity.java
package com.hmkcode.android;
 
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
 
public class AnotherActivity extends Activity {
 
    TextView tvPerson;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_another);
 
        // 1. get passed intent 
        Intent intent = getIntent();
 
        // 2. get person object from intent
 
        Person person = (Person) intent.getSerializableExtra("person");
 
        // 3. get reference to person textView 
        tvPerson = (TextView) findViewById(R.id.tvPerson);
 
        // 4. display name & age on textView 
        tvPerson.setText(person.toString());
 
    }
}
 
(3.3)Define Activities in the Manifest XML File
 
<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.hmkcode.android"

    android:versionCode="1"

    android:versionName="1.0" >

 

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="17" />

 

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

 

        <activity

            android:name="com.hmkcode.android.MainActivity"

            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="com.hmkcode.android.AnotherActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="com.hmkcode.android.ANOTHER_ACTIVITY" />

                <category android:name="android.intent.category.DEFAULT" />

            </intent-filter>

        </activity>

    </application>

 

</manifest>
 
參考資料:http://hmkcode.com/android-passing-java-object-another-activity/
(4)Android ImageButton Example Code  1) XML File: activity_main
<?xml version="1.0" encoding="utf-8"?>

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context="com.example.faraz.imagebutton_example.MainActivity">
    <ImageButton

        android:id="@+id/imageButton1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:src="@drawable/finger"

        tools:layout_editor_absoluteX="130dp"

        tools:layout_editor_absoluteY="155dp" />

</android.support.constraint.ConstraintLayout>
2) File: MainActivity.java
package com.example.faraz.imagebutton_example;
import android.app.Activity;

import android.os.Bundle;

import android.widget.ImageButton;

import android.widget.Toast;

import android.view.View;

import android.view.View.OnClickListener;
public class MainActivity extends Activity {
    ImageButton imageButton;
    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
        addListenerOnButton();
    }
    public void addListenerOnButton() {
        imageButton = (ImageButton) findViewById(R.id.imageButton1);
        imageButton.setOnClickListener(new OnClickListener() {
            @Override

            public void onClick(View arg0) {
                Toast.makeText(MainActivity.this, "You Clicked Image Button!", Toast.LENGTH_LONG).show();
            }
        });
    }
}
參考資料:https://www.includehelp.com/android/ImageButton-Example-Code.aspx
 
(4)
android 的view類的setVisibility();值的意思android view setVisibility():
有三個參數：Parameters: visibility One of VISIBLE , INVISIBLE , or GONE，想對應的三個常量值：0、4、8
VISIBLE:0 意思是可見的
INVISIBILITY:4 意思是不可見的，但還佔著原來的空間
GONE:8 意思是不可見的，不佔用原來的佈局空間
 
View Code 
 LinearLayout num_Layout = (LinearLayout) findViewById(R.id.num_layout);
  if (numberOfRecord > 0){ 
              TextView num = (TextView) findViewById(R.id.num);
              num.setText(numberOfRecord.toString() );
              num_Layout.setVisibility(0); 
         } 
else {
              num_Layout.setVisibility(8);
         }