Question

I’m trying to move the position of the seekbar using a button. Basically I have a seekbar from 0 to 100. and I have button presents set up at arbitrary values (40,50,60 etc). When I try to set the progress on the seekbar via button, I get a fault.. I’ve already initialized the seekBar in the onCreate() method.

    SeekBar seekBar = (SeekBar) findViewById(R.id.seekBar1);
    currentProgress = 40;
    seekBar.setMax(100);
    seekBar.setProgress(currentProgress);
    button40.setOnClickListener(button40Listener);

But when use the below, it crashes.

    private OnClickListener button40Listener = new OnClickListener() {
        public void onClick(View v) {
          currentProgress = 40;
          seekBar.setProgress(currentProgress);
        }
    }

This seems straight-forward. Any ideas?

Answer 1

You shouldn’t need to put up another Seekbar. The initial one should be fine. Without the exception message and stack trace I’m not sure what is causing the crash. However, I just coded an example and works as you would expect. Perhaps by looking at my example you can identify your issue.

SeekbarTest.java:

package com.example.seekbartest;

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

public class SeekbarTest extends Activity {
/** Called when the activity is first created. */
private SeekBar seekBar;

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

    seekBar = (SeekBar)findViewById(R.id.seekBar1);

    Button fortyPctButton = (Button)findViewById(R.id.buttonFortyPct);
    fortyPctButton.setOnClickListener(new OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            seekBar.setProgress(40);
        }
    });

    Button sixtyPctButton = (Button)findViewById(R.id.buttonSixtyPct);
    sixtyPctButton.setOnClickListener(new OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            seekBar.setProgress(60);
        }
    });

    Button eightyPctButton = (Button)findViewById(R.id.buttonEightyPct);
    eightyPctButton.setOnClickListener(new OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            seekBar.setProgress(80);
        }
    });
    }
}

And here is the main.xml it is referencing for the layout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:text="@string/hello"
    android:id="@+id/textView1" 
    android:layout_height="wrap_content" 
    android:layout_alignParentTop="true"/>

<SeekBar 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/seekBar1" 
    android:layout_below="@+id/textView1" 
    android:layout_alignLeft="@+id/textView1" 
    android:layout_alignRight="@+id/textView1"/>

<Button 
    android:layout_width="wrap_content" 
    android:text="40%" 
    android:id="@+id/buttonFortyPct" 
    android:layout_height="wrap_content" 
    android:layout_below="@+id/seekBar1"
    android:layout_alignLeft="@+id/seekBar1"/>

<Button 
    android:layout_width="wrap_content" 
    android:text="60%" 
    android:id="@+id/buttonSixtyPct" 
    android:layout_height="wrap_content" 
    android:layout_toRightOf="@+id/buttonFortyPct" 
    android:layout_alignTop="@+id/buttonFortyPct" 
    android:layout_alignBottom="@+id/buttonFortyPct"/>

<Button 
    android:layout_width="wrap_content" 
    android:text="80%" 
    android:id="@+id/buttonEightyPct" 
    android:layout_height="wrap_content" 
    android:layout_toRightOf="@+id/buttonSixtyPct" 
    android:layout_alignTop="@+id/buttonSixtyPct" 
    android:layout_alignBottom="@+id/buttonSixtyPct"/>
</RelativeLayout>

Just create a new android app and replace the generated code + layout with the example above. It should work for you.

Good luck,
Craig