MethodCall.java

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
package io.flutter.plugin.common;
 
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import io.flutter.BuildConfig;
import java.util.Map;
import org.json.JSONObject;
 
/** Command object representing a method call on a {@link MethodChannel}. */
public final class MethodCall {
  /** The name of the called method. */
  public final String method;
 
  /**
   * Arguments for the call.
   *
   * <p>Consider using {@link #arguments()} for cases where a particular run-time type is expected.
   * Consider using {@link #argument(String)} when that run-time type is {@link Map} or {@link
   * JSONObject}.
   */
  public final Object arguments;
 
  /**
   * Creates a {@link MethodCall} with the specified method name and arguments.
   *
   * @param method the method name String, not null.
   * @param arguments the arguments, a value supported by the channel's message codec. Possibly,
   *     null.
   */
  public MethodCall(@NonNull String method, @Nullable Object arguments) {
    if (BuildConfig.DEBUG && method == null) {
      throw new AssertionError("Parameter method must not be null.");
    }
    this.method = method;
    this.arguments = arguments;
  }
 
  /**
   * Returns the arguments of this method call with a static type determined by the call-site.
   *
   * @param <T> the intended type of the arguments.
   * @return the arguments with static type T
   */
  @SuppressWarnings("unchecked")
  @Nullable
  public <T> T arguments() {
    return (T) arguments;
  }
 
  /**
   * Returns a String-keyed argument of this method call, assuming {@link #arguments} is a {@link
   * Map} or a {@link JSONObject}. The static type of the returned result is determined by the
   * call-site.
   *
   * @param <T> the intended type of the argument.
   * @param key the String key.
   * @return the argument value at the specified key, with static type T, or {@code null}, if such
   *     an entry is not present.
   * @throws ClassCastException if {@link #arguments} can be cast to neither {@link Map} nor {@link
   *     JSONObject}.
   */
  @SuppressWarnings("unchecked")
  @Nullable
  public <T> T argument(@NonNull String key) {
    if (arguments == null) {
      return null;
    } else if (arguments instanceof Map) {
      return (T) ((Map<?, ?>) arguments).get(key);
    } else if (arguments instanceof JSONObject) {
      return (T) ((JSONObject) arguments).opt(key);
    } else {
      throw new ClassCastException();
    }
  }
 
  /**
   * Returns whether this method call involves a mapping for the given argument key, assuming {@link
   * #arguments} is a {@link Map} or a {@link JSONObject}. The value associated with the key, as
   * returned by {@link #argument(String)}, is not considered, and may be {@code null}.
   *
   * @param key the String key.
   * @return {@code true}, if {@link #arguments} is a {@link Map} containing key, or a {@link
   *     JSONObject} with a mapping for key.
   * @throws ClassCastException if {@link #arguments} can be cast to neither {@link Map} nor {@link
   *     JSONObject}.
   */
  public boolean hasArgument(@NonNull String key) {
    if (arguments == null) {
      return false;
    } else if (arguments instanceof Map) {
      return ((Map<?, ?>) arguments).containsKey(key);
    } else if (arguments instanceof JSONObject) {
      return ((JSONObject) arguments).has(key);
    } else {
      throw new ClassCastException();
    }
  }
}