Question

我创建了将数据发送到数据库的注册活动，按钮必须打开另一个活动，即MainActivity。代码工作正常，但有一个问题。单击该按钮时，它会响应并将信息发送到数据库，但活动不会更改。

如何更改代码以打开其他活动？

RegisterRequest.java

public class RegisterRequest extends StringRequest {

private static final String REGISTER_REQUEST_URL = "http://loginacti.comli.com/Register.php";
private Map<String, String> params;

public RegisterRequest(String Expect, String Prize, String Name, String Email, Response.Listener<String> listener) {
        super(Method.POST, REGISTER_REQUEST_URL, listener, null);
    params = new HashMap<>();
    params.put("Expect", Expect);
    params.put("Prize", Prize);
    params.put("Name", Name);
    params.put("Email", Email);

}

@Override
public Map<String, String> getParams() {
    return params;
}

RegisterActivity.java

public class RegisterActivity extends AppCompatActivity {

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

    final EditText etUknown = (EditText) findViewById(R.id.etUknown);
    final EditText etPrize = (EditText) findViewById(R.id.etPrize);
    final EditText etName = (EditText) findViewById(R.id.etName);
    final EditText etEmail = (EditText) findViewById(R.id.etEmail);
    final Button bRegister = (Button) findViewById(R.id.bRegister);

    bRegister.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            final String Expect = etUknown.getText().toString();
            final String Prize = etPrize.getText().toString();
            final String Name = etName.getText().toString();
            final String Email = etEmail.getText().toString();


            Response.Listener<String> responseListener = new Response.Listener<String>(){

                @Override
                public void onResponse(String response) {
                    try {
                        JSONObject jsonResponse = new JSONObject(response);
                        boolean success = jsonResponse.getBoolean("success");
                        if (success){
                            Intent intent = new Intent(RegisterActivity.this, MainActivity.class);
                            RegisterActivity.this.startActivity(intent);
                        }else{
                            AlertDialog.Builder builder = new AlertDialog.Builder(RegisterActivity.this);
                            builder.setMessage("Register Failed")
                                    .setNegativeButton("Retry", null)
                                    .create()
                                    .show();

                        }

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            };


            RegisterRequest registerRequest = new RegisterRequest(Expect, Prize, Name, Email, responseListener);
            RequestQueue queue = Volley.newRequestQueue(RegisterActivity.this);
            queue.add(registerRequest);
        }
    });
}

MainActivity.java

public class MainActivity extends AppCompatActivity {

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


    final TextView registerLink = (TextView) findViewById(R.id.eRegister);

    registerLink.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent registerIntent = new Intent(MainActivity.this, RegisterActivity.class);
            MainActivity.this.startActivity(registerIntent);
        }
    });
}

清单

<uses-permission android:name="android.permission.INTERNET"></uses-permission>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".RegisterActivity"></activity>
</application>

activity_register.xml

    <EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/etUknown"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_marginTop="60dp"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:hint="Numbers" />

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/etPrize"
    android:hint="Secret CD"
    android:layout_below="@+id/etUknown"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignRight="@+id/etUknown"
    android:layout_alignEnd="@+id/etUknown" />

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:inputType="textPersonName"
    android:ems="10"
    android:id="@+id/etName"
    android:hint="Full Name"
    android:layout_below="@+id/etPrize"
    android:layout_alignRight="@+id/etPrize"
    android:layout_alignEnd="@+id/etPrize"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:inputType="textEmailAddress"
    android:ems="10"
    android:id="@+id/etEmail"
    android:hint="New Email"
    android:layout_below="@+id/etName"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignRight="@+id/etName"
    android:layout_alignEnd="@+id/etName" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Register"
    android:id="@+id/bRegister"
    android:layout_marginTop="46dp"
    android:layout_below="@+id/etEmail"
    android:layout_centerHorizontal="true" />

Answer 1

在onclick中你不能使用.finish（），它通常会退出当前活动。但是，您可以创建一个方法exitActivity（），然后从您的onclick中调用它。因此，在写入数据库之后，在onClick结束时，使用以下命令创建一个try块：

try {
     exitActivity();
}
catch (Exception e){
      e.printStackTrace();
}

然后在您的RegisterActivity中创建一个exitActivity（），如下所示：

private void exitActivity(){
    this.finish();
}

你想这样做，因为如果你这样做，你会在尝试注册更多项目时制作多个主要活动实例。这可能会导致您的应用最终耗尽内存。

Answer 2

再添加一项权限ACCESS_NETWORK_STATE

<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
    </activity>
    <activity android:name=".RegisterActivity"></activity>
</application>

Answer 3

它会抛出错误还是只是无所事事？

你也可以尝试：

Intent registerIntent = new Intent(this, MainActivity.class);
startActivity(registerIntent);

而不是

Intent intent = new Intent(RegisterActivity.this, MainActivity.class);
RegisterActivity.this.startActivity(intent);

Answer 4

在＆＃39; onClick＆＃39;中尝试这一行代码方法：

startActivity(new Intent(MainActivity.this, RegisterActivity.class));

代码不起作用，按钮没有响应

4 个答案: