小编Mal*_*lum的帖子

我想在TextView中显示我当前的应用程序版本,Textview所在的活动不是我的MainACtivity.我使用了下面的代码:

public class informatie extends ActionBarActivity {

    public String versionName;

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

        try {
           versionName = getApplicationContext().getPackageManager().getPackageInfo(getApplicationContext().getPackageName(), 0).versionName;
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }

        Typeface impact = Typeface.createFromAsset(getAssets(), "fonts/Impact.ttf");

        TextView versieVak = (TextView) findViewById(R.id.versieView);
        versieVak.setText(versionName);
        Toast.makeText(getApplicationContext(), "KLIK", Toast.LENGTH_LONG).show();
        versieVak.setTypeface(impact);
        versieVak.setTextColor(getResources().getColor(R.color.antraciet));
        versieVak.setTextSize(10, TypedValue.COMPLEX_UNIT_SP);

    }

Layout.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"
    tools:context="com.KnapperDev.knapper.jrw.informatie">

        <ImageView
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:id="@+id/imageView"
            android:src="@drawable/overeenkomst"
            android:layout_marginBottom="249dp"
            android:layout_alignParentBottom="true"
            android:layout_centerHorizontal="true" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="100dp"
            android:id="@+id/versieView"
            android:layout_alignParentBottom="true"
            android:layout_centerHorizontal="true"
            android:layout_marginBottom="155dp" />
    </RelativeLayout>

但是当我在手机上打开活动时,TextView中没有任何内容.我做了一个Toast来检查是否versieVak.setText(versionName);使用过.它只是没有显示任何东西.知道我做错了什么吗？

public void onClick(View v){
    switch(v.getId()){
        case R.id.bereken:

           EditText basis = (EditText)findViewById(R.id.Basis);
              String tussenBasis = basis.getText().toString();
                Double.valueOf(tussenBasis);
            //

            EditText hoogte = (EditText)findViewById(R.id.Hoogte);
              String tussenHoogte = hoogte.getText().toString();
                Double.valueOf(tussenHoogte);

            double half = 1 / 2;
            //half = 0,5

            double einde = half * basis * hoogte;
            //eind antwoord formule

            ((TextView)findViewById(R.id.antwoord)).setText("Het antwoord is: " + einde);
            break;
    }

     }
}

我正在尝试为三角形区域制作一个简单的计算器,但我似乎被困在这里.