Programmatically Switch Android Input Methods with UiAutomator and ADB

Purpose

When UiAutomator tests need the UTF‑7 input method, the device’s default input method must be switched before the test and restored afterwards. The following Java utilities automate this process via ADB, suitable for multiple test devices.

Switch to UTF‑7 IME

public void setMobileInputMethodToUtf() {
    execCmdAdb("adb shell settings put secure default_input_method jp.jun_nama.test.utf7ime/.Utf7ImeService");
}

Sets the secure setting default_input_method to the component name of the UTF‑7 IME ( jp.jun_nama.test.utf7ime/.Utf7ImeService).

Switch to an alternative IME

public void setMobileInputMethodToOthers() {
    List<String> imeList = execCmdAndReturnResult("adb shell ime list -s");
    for (String ime : imeList) {
        if (!ime.contains("utf7ime")) {
            execCmdAdb("adb shell settings put secure default_input_method " + ime);
            break; // use the first non‑UTF‑7 IME
        }
    }
}

Retrieves the list of enabled input methods with adb shell ime list -s, skips the UTF‑7 entry, and sets the first remaining IME as the default.

Helper: Execute an ADB command without return value

public void execCmdAdb(String cmd) {
    System.out.println("Executing: " + cmd);
    String os = System.getProperty("os.name");
    try {
        Process p = os.contains("Mac")
                ? Runtime.getRuntime().exec(ADB_PATH + cmd)
                : Runtime.getRuntime().exec("cmd /c " + cmd);
        // Standard output
        try (BufferedReader r = new BufferedReader(new InputStreamReader(p.getInputStream()))) {
            String line;
            while ((line = r.readLine()) != null) {
                System.out.println(line);
                saveToFile(line, "runlog.log");
            }
        }
        // Error output
        try (BufferedReader er = new BufferedReader(new InputStreamReader(p.getErrorStream()))) {
            String line;
            while ((line = er.readLine()) != null) {
                System.err.println(line);
                saveToFile(line, "runlog.log");
            }
        }
    } catch (IOException e) {
        System.err.println("Command failed: " + cmd);
        e.printStackTrace();
    }
}

The method runs the supplied command, prints both stdout and stderr, and appends each line to runlog.log. It distinguishes macOS (uses ADB_PATH) from Windows (prefixes cmd /c).

Helper: Execute an ADB command and capture output

public List<String> execCmdAndReturnResult(String cmd) {
    System.out.println("Executing: " + cmd);
    List<String> result = new ArrayList<>();
    String os = System.getProperty("os.name");
    try {
        Process p = os.contains("Mac")
                ? Runtime.getRuntime().exec(ADB_PATH + cmd)
                : Runtime.getRuntime().exec("cmd /c " + cmd);
        try (BufferedReader r = new BufferedReader(new InputStreamReader(p.getInputStream()))) {
            String line;
            while ((line = r.readLine()) != null) {
                result.add(line);
            }
        }
    } catch (IOException e) {
        System.err.println("Command failed: " + cmd);
        e.printStackTrace();
    }
    return result;
}

This variant returns the command’s output lines as a List<String>, which is used by the IME‑switching logic.

Integration note

Include these utilities in a UiAutomator test suite and invoke setMobileInputMethodToUtf() before a test that requires the UTF‑7 keyboard, then call setMobileInputMethodToOthers() after the test to restore a regular input method. The approach works across multiple devices without manual interaction. Ensure that ADB_PATH points to the adb executable (e.g., /path/to/adb) and that saveToFile(String text, String fileName) is implemented according to your logging policy.