Java 制作一个android应用程序来添加两个数字
用户在EditText中输入两个数字,单击按钮,它们的总和将显示在TextView字段中。在emulator上运行我的代码时,我发现Launcher停止工作。 以下是我的java代码:Java 制作一个android应用程序来添加两个数字,java,android,Java,Android,用户在EditText中输入两个数字,单击按钮,它们的总和将显示在TextView字段中。在emulator上运行我的代码时,我发现Launcher停止工作。 以下是我的java代码: package com.snandi.sum; import android.support.v7.app.ActionBarActivity; import android.support.v7.app.ActionBar; import android.support.v4.app.Fragment; i
package com.snandi.sum;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.os.Build;
public class MainActivity extends ActionBarActivity {
TextView tv;
EditText et1;
EditText et2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b=(Button) findViewById(R.id.button1);
tv=(TextView) findViewById(R.id.textView1);
et1=(EditText) findViewById(R.id.editText1);
et2=(EditText) findViewById(R.id.editText2);
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0)
{
int int1 = Integer.parseInt(et1.getText().toString().trim());//Edited line
int int2 = Integer.parseInt(et2.getText().toString().trim());//edited line
int sum = int1 + int2;
//display the sum on the textView
tv.setText(String.valueOf(sum));
}
});
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
@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, 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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
以下是我的xml代码:
<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.snandi.sum.MainActivity$PlaceholderFragment" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button1"
android:layout_alignParentTop="true"
android:layout_marginTop="25dp"
android:text="0" />
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="@+id/textView1"
android:ems="10" />
<EditText
android:id="@+id/editText2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="@+id/editText1"
android:layout_marginTop="39dp"
android:ems="10" >
<requestFocus />
</EditText>
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/editText2"
android:layout_below="@+id/editText2"
android:layout_marginRight="31dp"
android:layout_marginTop="80dp"
android:text="Button" />
</RelativeLayout>
您可以发布您的logcat日志,以便我们查看错误是什么:启动器停止工作意味着模拟器不工作,代码中没有问题,尝试在不同的模拟器中运行代码。logcat显示以下消息07-04 15:42:58.108:D/AndroidRuntime1372:关闭VM 07-04 15:42:58.108:W/dalvikvm1372:threadid=1:线程退出,未捕获异常组=0xb3a4cba8 07-04 15:42:58.118:E/AndroidRuntime1372:致命异常:main 07-04 15:42:58.118:E/AndroidRuntime1372:进程:com.snandi.numbers,PID:1372 07-04 15:42:58.118:E/AndroidRuntime1372:java.lang.RuntimeException:无法启动活动组件信息{com.snandi.numbers/com.snandi.numbers.MainActivity}:java.lang。NullPointerException@DhawalSodha Parmar Emulator在其他应用程序中运行良好