在我的一个活动中,我有一个菜单选项和文本选项。当用户点击它时,它会重定向到另一个布局,在那里我放置了两个按钮,一个是加号按钮,另一个是减号按钮。
当用户点击该按钮时,我想要更改BackStack Activity的TextView文本大小。
以下是我的代码,当我点击该菜单选项时,应用程序崩溃并在Logcat中报告NullPointerException。
我的详细活动
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.detail_activity);
detailtext= (TextView) findViewById(R.id.detail);
dbHelper = new SqlLiteDbHelper(this);
try {
dbHelper.openDataBase();
} catch (SQLException e) {
e.printStackTrace();
}
sqLiteDatabase = dbHelper.getReadableDatabase();
cursor=dbHelper.getdetails(sqLiteDatabase, selectedData);
if(cursor.moveToFirst())
{
detailtext.setText(cursor.getString(0));
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id==R.id.text_option)
{
Intent intent= new Intent(this,CustomSetting.class);
startActivity(intent);
}
return super.onOptionsItemSelected(item);
}
Detail_menu.xml
<item android:id="@+id/text_option"
android:orderInCategory="100"
android:showAsAction="ifRoom"
android:title="Text Option"
/>
CustomSetting.java
public class CustomSetting extends AppCompatActivity {
DetailActivity detailActivity;
ImageButton plus,minus,close;
int txtSize = 14;
TextView detail=detailActivity.detailtext;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.custom_setting);
plus= (ImageButton) findViewById(R.id.plus);
minus= (ImageButton) findViewById(R.id.minus);
close= (ImageButton) findViewById(R.id.close);
plus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (detail.getTextSize() == 14 ||detail.getTextSize() == 15 || detail.getTextSize() == 16 || detail.getTextSize() == 17){
txtSize++;
detail.setTextSize(txtSize);
} else if (detail.getTextSize() == 18) {
txtSize+= 0;
detail.setTextSize(txtSize);
} else{
txtSize+= 0;
detail.setTextSize(txtSize);
}
}
});
minus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (detail.getTextSize() == 15||detail.getTextSize() ==16||detail.getTextSize() ==17|detail.getTextSize() ==18){
txtSize--;
detail.setTextSize(txtSize);
} else {
txtSize += 0;
detail.setTextSize(txtSize);
}
}
});
close.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent= new Intent(CustomSetting.this,DetailActivity.class);
startActivity(intent);
}
});
}
custom_setting.xml
<ImageButton
android:layout_width="50dp"
android:layout_height="40dp"
android:background="@drawable/close"
android:layout_above="@+id/textView"
android:layout_toRightOf="@+id/minus"
android:layout_toEndOf="@+id/minus"
android:id="@+id/close"
/>
<ImageButton
android:layout_width="50dp"
android:layout_height="40dp"
android:background="@drawable/plusign"
android:layout_marginTop="110dp"
android:id="@+id/plus"
android:layout_alignParentTop="true"
android:layout_alignLeft="@+id/textView"
android:layout_alignStart="@+id/textView" />
<ImageButton
android:layout_width="50dp"
android:layout_height="40dp"
android:background="@drawable/minusign"
android:id="@+id/minus"
android:layout_alignTop="@+id/plus"
android:layout_alignRight="@+id/textView"
android:layout_alignEnd="@+id/textView" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Change Text Size"
android:id="@+id/textView"
android:layout_above="@+id/minus"
android:layout_centerHorizontal="true"
android:textColor="#FFFFFF"
/>
日志记录:
Process: com.example.aa.sidd, PID: 23413
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.aa.sidd/com.example.aa.sidd.CustomSetting}: android.view.InflateException: Binary XML file line #17: Error inflating class <unknown>
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2436)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2498)
at android.app.ActivityThread.access$900(ActivityThread.java:179)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1324)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5641)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1288)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1104)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.view.InflateException: Binary XML file line #17: Error inflating class <unknown>
at android.view.LayoutInflater.createView(LayoutInflater.java:626)
custom_setting
布局可能没有一个 id 为plus
的视图。 - 1615903