Android简单程序 - 未创建SeekBar

Question

我正在开发我的第一个Android应用程序来独立控制20个RGB LED，我现在正在研究基本的GUI结构。我的第一个窗格几乎完美地工作（setPressed方法没有按照我希望的那样做，并且该类尚未优化）但是我的第二个窗格没有显示我创建的对象。这是我的第一个和第二个窗格的代码：

activity_controller.xml：

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".Controller"
    android:orientation="horizontal">
    <LinearLayout
        android:id="@+id/row1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        style="?android:attr/buttonBarStyle">
        <Button
            android:id="@+id/button0"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button0"
            android:onClick="toggleButton0"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button1"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button1"
            android:onClick="toggleButton1"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button2"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button2"
            android:onClick="toggleButton2"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button3"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button3"
            android:onClick="toggleButton3"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button4"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button4"
            android:onClick="toggleButton4"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button5"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button5"
            android:onClick="toggleButton5"
            style="?android:attr/buttonStyleToggle"/>
    </LinearLayout>

    <LinearLayout
        android:id="@+id/row2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/row1"
        style="?android:attr/buttonBarStyle">
        <Button
            android:id="@+id/button6"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button6"
            android:onClick="toggleButton6"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/buttonAll"
            android:layout_weight="4"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/buttonAll"
            android:onClick="selectAll"/>
        <Button
            android:id="@+id/button7"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button7"
            android:onClick="toggleButton7"
            style="?android:attr/buttonStyleToggle"/>
    </LinearLayout>

    <LinearLayout
        android:id="@+id/row3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/row2"
        style="?android:attr/buttonBarStyle">
        <Button
            android:id="@+id/button8"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button8"
            android:onClick="toggleButton8"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/buttonSet"
            android:layout_weight="4"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/buttonSet"
            android:onClick="setColor"/>
        <Button
            android:id="@+id/button9"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button9"
            android:onClick="toggleButton9"
            style="?android:attr/buttonStyleToggle"/>
    </LinearLayout>

    <LinearLayout
        android:id="@+id/row4"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/row3"
        style="?android:attr/buttonBarStyle">
        <Button
            android:id="@+id/button10"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button10"
            android:onClick="toggleButton10"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/buttonOff"
            android:layout_weight="4"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/buttonOff"
            android:onClick="turnOff"/>
        <Button
            android:id="@+id/button11"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button11"
            android:onClick="toggleButton11"
            style="?android:attr/buttonStyleToggle"/>
    </LinearLayout>

    <LinearLayout
        android:id="@+id/row5"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/row4"
        style="?android:attr/buttonBarStyle">
        <Button
            android:id="@+id/button12"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button12"
            android:onClick="toggleButton12"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/buttonBuiltIn"
            android:layout_weight="4"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/buttonBuiltIn"
            android:onClick="builtIns"/>
        <Button
            android:id="@+id/button13"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button13"
            android:onClick="toggleButton13"
            style="?android:attr/buttonStyleToggle"/>
    </LinearLayout>

    <LinearLayout
        android:id="@+id/row6"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/row5"
        style="?android:attr/buttonBarStyle">
        <Button
            android:id="@+id/button14"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button14"
            android:onClick="toggleButton14"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button15"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button15"
            android:onClick="toggleButton15"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button16"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button16"
            android:onClick="toggleButton16"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button17"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button17"
            android:onClick="toggleButton17"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button18"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button18"
            android:onClick="toggleButton18"
            style="?android:attr/buttonStyleToggle"/>
        <Button
            android:id="@+id/button19"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/button19"
            android:onClick="toggleButton19"
            style="?android:attr/buttonStyleToggle"/>
    </LinearLayout>
</RelativeLayout>

Controller.java：

package com.example.lightcontrol;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;


public class Controller extends Activity {
    public final static String SELECTED_BUTTONS = "com.mycompany.myfirstapp.BUTTONS";
    public final static boolean[] selectedButtons = new boolean[20];

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_controller);
        int i = 0;
        while (i < 20) {
            selectedButtons[i]=false;
            i++;
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_controller, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public void toggleButton0(View view) {
        if (!selectedButtons[0]) {
            view.setPressed(true);
            selectedButtons[0] = true;
        } else {
            view.setPressed(false);
            selectedButtons[0] = false;
        }
    }

    public void toggleButton1(View view) {
        if (!selectedButtons[1]) {
            view.setPressed(true);
            selectedButtons[1] = true;
        } else {
            view.setPressed(false);
            selectedButtons[1] = false;
        }
    }

    public void toggleButton2(View view) {
        if (!selectedButtons[2]) {
            view.setPressed(true);
            selectedButtons[2] = true;
        } else {
            view.setPressed(false);
            selectedButtons[2] = false;
        }
    }

    public void toggleButton3(View view) {
        if (!selectedButtons[3]) {
            view.setPressed(true);
            selectedButtons[3] = true;
        } else {
            view.setPressed(false);
            selectedButtons[3] = false;
        }
    }

    public void toggleButton4(View view) {
        if (!selectedButtons[4]) {
            view.setPressed(true);
            selectedButtons[4] = true;
        } else {
            view.setPressed(false);
            selectedButtons[4] = false;
        }
    }

    public void toggleButton5(View view) {
        if (!selectedButtons[5]) {
            view.setPressed(true);
            selectedButtons[5] = true;
        } else {
            view.setPressed(false);
            selectedButtons[5] = false;
        }
    }

    public void toggleButton6(View view) {
        if (!selectedButtons[6]) {
            view.setPressed(true);
            selectedButtons[6] = true;
        } else {
            view.setPressed(false);
            selectedButtons[6] = false;
        }
    }

    public void toggleButton7(View view) {
        if (!selectedButtons[7]) {
            view.setPressed(true);
            selectedButtons[7] = true;
        } else {
            view.setPressed(false);
            selectedButtons[7] = false;
        }
    }

    public void toggleButton8(View view) {
        if (!selectedButtons[8]) {
            view.setPressed(true);
            selectedButtons[8] = true;
        } else {
            view.setPressed(false);
            selectedButtons[8] = false;
        }
    }

    public void toggleButton9(View view) {
        if (!selectedButtons[9]) {
            view.setPressed(true);
            selectedButtons[9] = true;
        } else {
            view.setPressed(false);
            selectedButtons[9] = false;
        }
    }

    public void toggleButton10(View view) {
        if (!selectedButtons[10]) {
            view.setPressed(true);
            selectedButtons[10] = true;
        } else {
            view.setPressed(false);
            selectedButtons[10] = false;
        }
    }

    public void toggleButton11(View view) {
        if (!selectedButtons[11]) {
            view.setPressed(true);
            selectedButtons[11] = true;
        } else {
            view.setPressed(false);
            selectedButtons[11] = false;
        }
    }

    public void toggleButton12(View view) {
        if (!selectedButtons[12]) {
            view.setPressed(true);
            selectedButtons[12] = true;
        } else {
            view.setPressed(false);
            selectedButtons[12] = false;
        }
    }

    public void toggleButton13(View view) {
        if (!selectedButtons[13]) {
            view.setPressed(true);
            selectedButtons[13] = true;
        } else {
            view.setPressed(false);
            selectedButtons[13] = false;
        }
    }

    public void toggleButton14(View view) {
        if (!selectedButtons[14]) {
            view.setPressed(true);
            selectedButtons[14] = true;
        } else {
            view.setPressed(false);
            selectedButtons[14] = false;
        }
    }

    public void toggleButton15(View view) {
        if (!selectedButtons[15]) {
            view.setPressed(true);
            selectedButtons[15] = true;
        } else {
            view.setPressed(false);
            selectedButtons[15] = false;
        }
    }

    public void toggleButton16(View view) {
        if (!selectedButtons[16]) {
            view.setPressed(true);
            selectedButtons[16] = true;
        } else {
            view.setPressed(false);
            selectedButtons[16] = false;
        }
    }

    public void toggleButton17(View view) {
        if (!selectedButtons[17]) {
            view.setPressed(true);
            selectedButtons[17] = true;
        } else {
            view.setPressed(false);
            selectedButtons[17] = false;
        }
    }

    public void toggleButton18(View view) {
        if (!selectedButtons[18]) {
            view.setPressed(true);
            selectedButtons[18] = true;
        } else {
            view.setPressed(false);
            selectedButtons[18] = false;
        }
    }

    public void toggleButton19(View view) {
        if (!selectedButtons[19]) {
            view.setPressed(true);
            selectedButtons[19] = true;
        } else {
            view.setPressed(false);
            selectedButtons[19] = false;
        }
    }

    /** Called when the user clicks the Send button */
    public void setColor(View view) {
        Intent intent = new Intent(this, DisplayMessageActivity.class);
        intent.putExtra(SELECTED_BUTTONS, selectedButtons);
        startActivity(intent);
    }
}

activity_display_message.xml：

<RelativeLayout
    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"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".DisplayMessageActivity"
    android:orientation="horizontal">
    <SeekBar
        android:id="@+id/redSlider"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="25dp"
        android:max="255"/>
    <SeekBar
        android:id="@+id/greenSlider"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:layout_below="@+id/redSlider"
        android:max="255"/>
    <SeekBar
        android:id="@+id/blueSlider"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:layout_below="@+id/greenSlider"
        android:max="255"/>
    <TextView
        android:id="@+id/colorBox"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentStart="true"/>
</RelativeLayout>

DisplayMessageActivity.java：

package com.example.lightcontrol;

import android.app.Activity;
import android.app.Fragment;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.SeekBar;
import android.widget.TextView;

import java.util.ArrayList;


public class DisplayMessageActivity extends Activity {

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

        // Get the message from the intent
        Intent intent = getIntent();
        boolean[] buttons = intent.getBooleanArrayExtra(Controller.SELECTED_BUTTONS);

        // Create the text view
        String message = "";
        int i = 0;
        for(boolean currButton: buttons) {
            if(currButton) {
               message += Integer.toString(i) + ",";
            }
            i++;
        }

        final SeekBar redSlider = (SeekBar) findViewById(R.id.redSlider);
        final SeekBar blueSlider = (SeekBar) findViewById(R.id.blueSlider);
        final SeekBar greenSlider = (SeekBar) findViewById(R.id.greenSlider);

        ArrayList<SeekBar> seekArray = new ArrayList<SeekBar>();
        seekArray.add(redSlider);
        seekArray.add(blueSlider);
        seekArray.add(greenSlider);
        for (SeekBar slider : seekArray) {
            slider.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
                int progress = 0;

                @Override
                public void onProgressChanged(SeekBar slider, int progresValue, boolean fromUser) {
                    updateColorBox();
                }

                @Override
                public void onStartTrackingTouch(SeekBar slider) {
                }

                @Override
                public void onStopTrackingTouch(SeekBar slider) {
                }
            });
        }

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


    public void updateColorBox() {
        SeekBar redSlider = (SeekBar) findViewById(R.id.redSlider);
        SeekBar blueSlider = (SeekBar) findViewById(R.id.blueSlider);
        SeekBar greenSlider = (SeekBar) findViewById(R.id.greenSlider);
        TextView colorBox = (TextView) findViewById(R.id.colorBox);

        int redProgress = redSlider.getProgress();
        int blueProgress = blueSlider.getProgress();
        int greenProgress = greenSlider.getProgress();
        String hex = String.format("%02x%02x%02x", redProgress, greenProgress, blueProgress);

        colorBox.setBackgroundColor(Color.parseColor(hex));
    }
}

有谁知道为什么DisplayMessageActivity窗格是空白的？它在我的xml设计预览选项卡中不是空白的...谢谢！

Answer 1

您在setContentView()

中错过了对onCreate()的来电