Question

我想在我的主要活动和我的第二个活动之间切换，但每当我这样做时，应用程序都会关闭。所以在我点击button1“Neues Feld”后，应用程序应切换到第二个活动：feldlayout.class，其布局为：feldlayout.xml！这些活动都在Android_MAnifest中，这也不是问题......

谢谢你的帮助！ 现在正在运行！我创建了一个新的View类，将其添加到布局中然后它运行正常！

主要类

package com.example.volleyballapp;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;
import android.widget.Button;

public class Main_Layout extends Activity {

 Button b1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);    
    setContentView(R.layout.main_layout);
     b1 = (Button) findViewById(R.id.button1);
     b1.setOnClickListener(myhandler);
}

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

View.OnClickListener myhandler = new View.OnClickListener(){
public void onClick(View v) {

    if(v==b1){
    Intent i = new Intent(Main_Layout.this, feldlayout.class);
    startActivity(i);
    }   
}
};}

主要布局

<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:background="@drawable/background2"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"   
tools:context=".Main_Layout" >

<TextView
    android:id="@+id/textView"
    android:layout_width="fill_parent"
    android:layout_height="250dp"
    android:layout_alignParentTop="true"

    android:layout_marginLeft="10sp"
    android:layout_marginRight="10sp"
    android:text=" "
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textColor="@color/farbe" />

<Button
    android:id="@+id/button1"
    style="@style/ButtonText"
    android:layout_below="@id/textView"
    android:layout_centerHorizontal="true"

    android:background="@drawable/bnt_black"
    android:onClick="NeuesFeldClick"
    android:text="Neues Feld" />

  <TextView 
        android:layout_width="fill_parent"
          android:layout_height="100dp"

          android:textAppearance="?android:attr/textAppearanceLarge"
          android:text=" "
          android:id="@+id/textView2"

          android:textColor="@color/farbe"
          android:layout_below="@id/button1"/>

 <Button
     android:id="@+id/button2"
     style="@style/ButtonText"
     android:layout_below="@id/textView2"
     android:layout_centerHorizontal="true"
     android:background="@drawable/bnt_black"
     android:onClick="LetztesFeldClick"
     android:text="Letztes Feld" />

  <TextView 
        android:layout_width="fill_parent"
          android:layout_height="100dp"

          android:textAppearance="?android:attr/textAppearanceLarge"
          android:text=" "
          android:id="@+id/textView3"

          android:textColor="@color/farbe"
          android:layout_below="@id/button2"/>

<Button
    android:id="@+id/button3"
    style="@style/ButtonText"
    android:layout_below="@id/textView3"
    android:layout_centerHorizontal="true"
    android:background="@drawable/bnt_black"
    android:onClick="SavesClick"
    android:text="Gespeicherte Felder" />
    </RelativeLayout>

第二项活动

package com.example.volleyballapp;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.View;

public class feldlayout extends Activity{
   public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.feldlayout);


   }

  private Paint paint = new Paint();
  private Path path = new Path();
  int count = 1;

  public feldlayout(Context context, AttributeSet attrs) {
    super();

    paint.setAntiAlias(true);
    paint.setStrokeWidth(6f);           //Breite des Strichs
    paint.setColor(Color.BLACK);        //Farbe des Strichs 
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeJoin(Paint.Join.ROUND);

  }

protected void onDraw(Canvas canvas) {

    if ((count%2 != 0)){
    canvas.drawPath(path, paint);}
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {
    float eventX = event.getX();
    float eventY = event.getY();

    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:

        count++;

        if(count%2 != 1){
        path.moveTo(eventX, eventY);
      return true;
        }
        if(count%2 != 0){
        path.lineTo(eventX, eventY);
        break;
        }
    case MotionEvent.ACTION_MOVE:

      break;
    case MotionEvent.ACTION_UP:
      // nothing to do
      break;
    default:
      return false;
    }
    // Schedules a repaint.
    invalidate();
    return true;
  }
private void invalidate() {
    // TODO Auto-generated method stub

}   
}

Answer 1

我试过了。你的代码工作正常。问题是你在第二个Activity中调用了Constructor。低于一。

 public feldlayout(Context context, AttributeSet attrs) {
    super();

    paint.setAntiAlias(true);
    paint.setStrokeWidth(6f);           //Breite des Strichs
    paint.setColor(Color.BLACK);        //Farbe des Strichs 
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeJoin(Paint.Join.ROUND);

  }

请删除此构造函数，然后重试。

注意只需创建一个单独的类并在那里调用constructor。

在Android中切换活动？

1 个答案: