Question

代码应该通过两个edittext字段获取两个数字，并且在单击按钮时textview应该打印结果。那么，有谁能告诉我我做错了什么？

public class MainActivity extends Activity {

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final Button c = (Button) findViewById(R.id.sum_button);

    c.setOnClickListener(new OnClickListener() {

        public void onClick(View arg0) {
            EditText n1 = (EditText) findViewById(R.id.add_no1);
            EditText n2 = (EditText) findViewById(R.id.add_no2);
            TextView sum_result = (TextView)findViewById(R.id.sum_result);
            int sum = 0,i=0,j=0;
            i=Integer.getInteger(n1.getText().toString());
            j=Integer.getInteger(n2.getText().toString());
            sum=i+j;
            sum_result.setText("the sum result is "+ sum);


        }
    });


}

@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;
}

}

这是我的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"
    android:background="#000000"
    android:orientation="horizontal"
    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=".MainActivity" >

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/number_ip_layout"
        android:layout_alignParentTop="true"
        android:layout_marginTop="83dp"
        android:orientation="horizontal"
        android:visibility="visible"
        android:weightSum="100" >

        <EditText
            android:id="@+id/add_no1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginLeft="30dp"
            android:layout_weight="40"
            android:background="#ffffff"
            android:cursorVisible="true"
            android:ems="10"
            android:inputType="number" >

            <requestFocus />
        </EditText>

        <EditText
            android:id="@+id/add_no2"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginLeft="100dp"
            android:layout_weight="40"
            android:background="#ffffff"
            android:cursorVisible="true"
            android:ems="10"
            android:inputType="number" />
    </LinearLayout>

    <Button
        android:id="@+id/sum_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/linearLayout1"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="56dp"
        android:background="#550000"
        android:text="sum" />

    <TextView
        android:id="@+id/sum_result"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/sum_button"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="128dp"
        android:textSize="20sp"
        android:singleLine="true"
        android:text="" />

</RelativeLayout>

Answer 1

它不是答案，但它有助于找到问题。

将onCreate函数更新为此。并查看onClick事件上的日志输出。让我知道日志输出。

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final Button c = (Button) findViewById(R.id.sum_button);
        final EditText n1 = (EditText) findViewById(R.id.add_no1);
        final EditText n2 = (EditText) findViewById(R.id.add_no2);
        final TextView sum_result = (TextView)findViewById(R.id.sum_result);

        c.setOnClickListener(new OnClickListener() {

            public void onClick(View arg0) {
                int sum = 0,i=0,j=0;
                Log.i("n1 is:", n1.getText().toString()+" number");
                Log.i("n2 is:", n2.getText().toString()+" number");
                i=Integer.getInteger(n1.getText().toString());
                j=Integer.getInteger(n2.getText().toString());
                sum=i+j;
                sum_result.setText("the sum result is "+ sum);

            }
        });


    }

为什么我的EditText返回null或空字符串？

1 个答案: