Is there a better way I can display different layouts in android?

Question

I am trying to make an app that has multiple layouts. Is there a certain efficient way to display multiple layouts? My app has buttons and each button leads to a different layout. Therefore, can anyone give me ideas on what to use? I am a 14 year old and i am completely new to android. I have a moderate amount of background in java, that's all. Thanks for any help! Here is my main activity...

package com.example.submenus;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
    public void onBackPressed()  {
        setContentView(R.layout.activity_main);


    }

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

        // This is for Audi A4
        Button button = (Button) findViewById(R.id.a4button);
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            setContentView(R.layout.audi);
            }

        }   ); 

        // This is for Audi A6
        Button button1 = (Button) findViewById(R.id.a6button);
    button1.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            setContentView(R.layout.audia6);
             }

        } ); 

        // This is for Audi Q5
         Button button2 = (Button) findViewById(R.id.q5button);
    button2.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            setContentView(R.layout.audiq5);

            }
    } ); 

        // This is for Audi R8
         Button button3 = (Button) findViewById(R.id.r8button);
    button3.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            setContentView(R.layout.audir8);

        }
    } );


    }
}

Again, just want to say this is an app that has a main menu. In that menu i have multiple buttons that lead to a different layout correspondingly. The app works fine until i hit the back button then click a button. Let me rephrase that... I click on a button and it takes me to the correct layout. I then can hit the back button and it brings the layout back to the main menu just like it should. Then if i click another button the app freezes and crashes. Is there a way to fix this? Thanks for any help!

[you asked the same question 2 days ago](http://stackoverflow.com/questions/20060715/when-i-use-the-back-button-in-activity-my-app-crashes-after-i-click-a-button-in) where they told you using setContentView() multiple times wouldn't work. — panini, Nov 21 '13 at 01:22
And the error is `NullPointerException`? You need to reassign `(Button) findViewById(BUTTON_ID)` and `OnClickListener` to `button`-`button3` — Aprian, Nov 21 '13 at 01:31
And why don't you just create 4 more activities? Or using [Fragment](http://developer.android.com/guide/components/fragments.html) to achieve what you want. — Aprian, Nov 21 '13 at 01:33

score 0 · Answer 1 · answered Nov 21 '13 at 01:50

This should fix your error, but I think this is a very bad approach.

public class MainActivity extends Activity {
    public void onBackPressed()  {
        // You need to re-findView and re-setOnClickListener to button-button3
        setMain();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setMain();
    }

    public void setMain() {
        setContentView(R.layout.activity_main); 

        // This is for Audi A4
        Button button = (Button) findViewById(R.id.a4button);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                setContentView(R.layout.audi);
            }
        }); 

        // This is for Audi A6
        Button button1 = (Button) findViewById(R.id.a6button);
        button1.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                setContentView(R.layout.audia6);
            }
        });

        // This is for Audi Q5
        Button button2 = (Button) findViewById(R.id.q5button);
        button2.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                setContentView(R.layout.audiq5);
            }
        }); 

        // This is for Audi R8
        Button button3 = (Button) findViewById(R.id.r8button);
        button3.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                setContentView(R.layout.audir8);
            }
        });
    }
}

You can create many activities, so what to do?

Create another class that extends Activity

public class ChildActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // Create another child.xml in your res > layout
        setContentView(R.layout.child);
    }
}

Register the activity under application tag in your AndroidManifest.xml
```
<activity name=".ChildActivity"/>
```

Call ChildActivity from your MainActivity

// This is for Audi A4
Button button = (Button) findViewById(R.id.a4button);
button.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {
        Intent childIntent = new Intent(MainActivity.this, ChildActivity.class);
        startActivity(childIntent); 
    }
});

And that's it. I hope I didn't leave out anything.

NOTE

If you are going to use activity approach. You should remove the onBackPressed method in your MainActivity.

Apria thank you very much for all of this but I just watched a tutorial on YouTube and decided i am going to use multiple activities which actually works! — Steve Sahayadarlin, Nov 21 '13 at 01:57

score 0 · Answer 2 · answered Nov 21 '13 at 04:33

// try this way
**main.xml**
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="5dp"
        android:gravity="center"
        android:orientation="vertical" >

        <LinearLayout
            android:id="@+id/lnrButton"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">
            <Button
                android:id="@+id/btnAudi4"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Audi4"/>

            <Button
                android:id="@+id/btnAudi6"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Audi6"/>

            <Button
                android:id="@+id/btnAudiQ5"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="AudiQ5"/>

            <Button
                android:id="@+id/btnAudiR8"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="AudiR8"/>

        </LinearLayout>

        <LinearLayout
            android:id="@+id/lnrAudi4"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:visibility="gone"
            android:orientation="vertical">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Audi4"/>

            <!--Write Audi4 layout shwon code here-->
        </LinearLayout>

        <LinearLayout
            android:id="@+id/lnrAudi6"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:visibility="gone"
            android:orientation="vertical">
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Audi6"/>

            <!--Write Audi6 layout shwon code here-->
        </LinearLayout>

        <LinearLayout
            android:id="@+id/lnrAudiQ5"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:visibility="gone"
            android:orientation="vertical">
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="AudiQ5"/>

            <!--Write AudiQ5 layout shwon code here-->
        </LinearLayout>

        <LinearLayout
            android:id="@+id/lnrAudiR8"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:visibility="gone"
            android:orientation="vertical">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="AudiR8"/>

            <!--Write AudiR8 layout shwon code here-->
        </LinearLayout>

    </LinearLayout>
</ScrollView>

**MainActivity**
public class MyActivity extends Activity {

    private Button btnAudi4;
    private Button btnAudi6;
    private Button btnAudiQ5;
    private Button btnAudiR8;

    private LinearLayout lnrButton;
    private LinearLayout lnrAudi4;
    private LinearLayout lnrAudi6;
    private LinearLayout lnrAudiQ5;
    private LinearLayout lnrAudiR8;

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

        lnrButton = (LinearLayout) findViewById(R.id.lnrButton);
        lnrAudi4 = (LinearLayout) findViewById(R.id.lnrAudi4);
        lnrAudi6 = (LinearLayout) findViewById(R.id.lnrAudi6);
        lnrAudiQ5 = (LinearLayout) findViewById(R.id.lnrAudiQ5);
        lnrAudiR8 = (LinearLayout) findViewById(R.id.lnrAudiR8);

        btnAudi4 = (Button) findViewById(R.id.btnAudi4);
        btnAudi6 = (Button) findViewById(R.id.btnAudi6);
        btnAudiQ5 = (Button) findViewById(R.id.btnAudiQ5);
        btnAudiR8 = (Button) findViewById(R.id.btnAudiR8);

        btnAudi4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                lnrButton.setVisibility(View.GONE);
                lnrAudi4.setVisibility(View.VISIBLE);
            }
        });
        btnAudi6.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                lnrButton.setVisibility(View.GONE);
                lnrAudi6.setVisibility(View.VISIBLE);
            }
        });
        btnAudiQ5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                lnrButton.setVisibility(View.GONE);
                lnrAudiQ5.setVisibility(View.VISIBLE);
            }
        });
        btnAudiR8.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                lnrButton.setVisibility(View.GONE);
                lnrAudiR8.setVisibility(View.VISIBLE);
            }
        });
    }

    @Override
    public void onBackPressed() {
        if(lnrButton.getVisibility()==View.GONE){
            lnrButton.setVisibility(View.VISIBLE);
            lnrAudi4.setVisibility(View.GONE);
            lnrAudi6.setVisibility(View.GONE);
            lnrAudiQ5.setVisibility(View.GONE);
            lnrAudiR8.setVisibility(View.GONE);
        }else{
            super.onBackPressed();
        }
    }
}

Is there a better way I can display different layouts in android?

2 Answers2