Question

我正在为我的学校开发一个应用程序，但是我无法继续使用我的display.class ...我不知道为什么它不起作用。当我点击按钮去另一个班级时，什么也没发生。

以下是我创建展示活动的意图：

Intent i = new Intent(CameraTestActivity.this, display.class);
startActivity(i);

我的AndroidManifest

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

我的显示活动：

package net.sourceforge.zbar.android.CameraTest;
import android.app.Activity;
import android.os.Bundle;

public class display extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {    
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.display); 
    } 
}

谢谢

编辑：

意图似乎有效，但我的手机屏幕上没有任何内容

[2015-01-08 10:15:14 - Consomattionchecker] ActivityManager：开始：Intent {act = android.intent.action.MAIN cat = [android.intent.category.LAUNCHER] cmp = net.sourceforge.zbar .android.CameraTest / .CameraTestActivity}

Edit2：CameraTestActivity代码

    public class CameraTestActivity extends Activity
{
    private Camera mCamera;
    private CameraPreview mPreview;
    private Handler autoFocusHandler;

    TextView scanText;
    Button scanButton;

    ImageScanner scanner;

    private boolean barcodeScanned = false;
    private boolean previewing = true;

    static {
        System.loadLibrary("iconv");
    } 

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

        setContentView(R.layout.main);

        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

        autoFocusHandler = new Handler();
        mCamera = getCameraInstance();

        /* Instance barcode scanner */
        scanner = new ImageScanner();
        scanner.setConfig(0, Config.X_DENSITY, 3);
        scanner.setConfig(0, Config.Y_DENSITY, 3);

        mPreview = new CameraPreview(this, mCamera, previewCb, autoFocusCB);
        FrameLayout preview = (FrameLayout)findViewById(R.id.cameraPreview);
        preview.addView(mPreview);

        scanText = (TextView)findViewById(R.id.scanText);

        scanButton = (Button)findViewById(R.id.ScanButton);

        scanButton.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (barcodeScanned) {
                        barcodeScanned = false;
                        scanText.setText("Scanning...");
                        mCamera.setPreviewCallback(previewCb);
                        mCamera.startPreview();
                        previewing = true;
                        mCamera.autoFocus(autoFocusCB);

                        //------------- try 
                        Intent i = new Intent(CameraTestActivity.this, display.class);
                        startActivity(i);
                        //-------------


                    }
                }
            });
    }

    @Override
    public void onPause() {
        super.onPause();
        releaseCamera();
    }

    /** A safe way to get an instance of the Camera object. */
    public static Camera getCameraInstance(){
        Camera c = null;
        try {
            c = Camera.open();
        } catch (Exception e){
        }
        return c;
    }

    private void releaseCamera() {
        if (mCamera != null) {
            previewing = false;
            mCamera.setPreviewCallback(null);
            mCamera.release();
            mCamera = null;
        }
    }

    private Runnable doAutoFocus = new Runnable() {
            @Override
            public void run() {
                if (previewing)
                    mCamera.autoFocus(autoFocusCB);
            }
        };

    PreviewCallback previewCb = new PreviewCallback() {
            @Override
            public void onPreviewFrame(byte[] data, Camera camera) {
                Camera.Parameters parameters = camera.getParameters();
                Size size = parameters.getPreviewSize();

                Image barcode = new Image(size.width, size.height, "Y800");
                barcode.setData(data);

                int result = scanner.scanImage(barcode);

                if (result != 0) {
                    previewing = false;
                    mCamera.setPreviewCallback(null);
                    mCamera.stopPreview();

                    SymbolSet syms = scanner.getResults();
                    for (Symbol sym : syms) {
                        scanText.setText("Valeur retournée " + sym.getData());
                        //----------
                        Context context = getApplicationContext();
                        CharSequence text = sym.getData();
                        int duration = Toast.LENGTH_SHORT;

                        Toast toast = Toast.makeText(context, text, duration);
                        toast.show();



                        //----------
                        barcodeScanned = true;
                    }
                }
            }
        };

    // Mimic continuous auto-focusing
    AutoFocusCallback autoFocusCB = new AutoFocusCallback() {
            @Override
            public void onAutoFocus(boolean success, Camera camera) {
                autoFocusHandler.postDelayed(doAutoFocus, 1000);
            }
        };
}

Answer 1

在AndroidManifest.xml我只能看到android:name=".display"

您还必须在其中添加其他活动

<activity

 android:name=".CameraTestActivity">
</activity>

还有一件事要告诉你，

Intent i = new Intent(MyCurrenctActivity.this, ActivityIwantToMoveTo.class); // replace the names of your activities accordingly.

修改

您已设置private boolean barcodeScanned = false

scanButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (barcodeScanned) { // this if block never gets executed since barcodeScanned is false barcodeScanned = false; scanText.setText("Scanning..."); mCamera.setPreviewCallback(previewCb); mCamera.startPreview(); previewing = true; mCamera.autoFocus(autoFocusCB); //------------- try Intent i = new Intent(CameraTestActivity.this, display.class); startActivity(i); //------------- } } });

将barcodeScanned更改为true

private boolean barcodeScanned = true;

这是你的基本错误

Answer 2

根据你的代码，你的Launcher活动应该是b CameraTestActivity和第二个活动应该显示所以你的清单文件应该像

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

    <activity 
        android:name=".display" >  
   </activity>

Android，Intent不起作用

2 个答案: